diff --git a/apisix/plugins/clickhouse-logger.lua b/apisix/plugins/clickhouse-logger.lua
index fd44e32fc1c1..30a8b0d354ab 100644
--- a/apisix/plugins/clickhouse-logger.lua
+++ b/apisix/plugins/clickhouse-logger.lua
@@ -17,7 +17,6 @@
 
 local bp_manager_mod  = require("apisix.utils.batch-processor-manager")
 local log_util        = require("apisix.utils.log-util")
-local plugin          = require("apisix.plugin")
 local core            = require("apisix.core")
 local http            = require("resty.http")
 local url             = require("net.url")
@@ -79,11 +78,6 @@ local metadata_schema = {
         log_format = {
             type = "object"
         },
-        max_pending_entries = {
-            type = "integer",
-            description = "maximum number of pending entries in the batch processor",
-            minimum = 1,
-        },
     },
 }
 
@@ -93,7 +87,7 @@ local _M = {
     priority = 398,
     name = plugin_name,
     schema = batch_processor_manager:wrap_schema(schema),
-    metadata_schema = metadata_schema,
+    metadata_schema = batch_processor_manager:wrap_metadata_schema(metadata_schema),
 }
 
 
@@ -189,12 +183,9 @@ end
 
 
 function _M.log(conf, ctx)
-    local metadata = plugin.plugin_metadata(plugin_name)
-    local max_pending_entries = metadata and metadata.value and
-                                metadata.value.max_pending_entries or nil
     local entry = log_util.get_log_entry(plugin_name, conf, ctx)
 
-    if batch_processor_manager:add_entry(conf, entry, max_pending_entries) then
+    if batch_processor_manager:add_entry(conf, entry) then
         return
     end
 
@@ -219,7 +210,7 @@ function _M.log(conf, ctx)
         return send_http_data(conf, data)
     end
 
-    batch_processor_manager:add_entry_to_new_processor(conf, entry, ctx, func, max_pending_entries)
+    batch_processor_manager:add_entry_to_new_processor(conf, entry, ctx, func)
 end
 
 
diff --git a/apisix/plugins/datadog.lua b/apisix/plugins/datadog.lua
index 05c21c6d5400..66e5e8ae1811 100644
--- a/apisix/plugins/datadog.lua
+++ b/apisix/plugins/datadog.lua
@@ -90,7 +90,7 @@ local _M = {
     priority = 495,
     name = plugin_name,
     schema = batch_processor_manager:wrap_schema(schema),
-    metadata_schema = metadata_schema,
+    metadata_schema = batch_processor_manager:wrap_metadata_schema(metadata_schema),
 }
 
 
diff --git a/apisix/plugins/elasticsearch-logger.lua b/apisix/plugins/elasticsearch-logger.lua
index 2d1dc7743397..0a787040b058 100644
--- a/apisix/plugins/elasticsearch-logger.lua
+++ b/apisix/plugins/elasticsearch-logger.lua
@@ -18,7 +18,6 @@ local core            = require("apisix.core")
 local http            = require("resty.http")
 local log_util        = require("apisix.utils.log-util")
 local bp_manager_mod  = require("apisix.utils.batch-processor-manager")
-local plugin          = require("apisix.plugin")
 local ngx             = ngx
 local ngx_re          = ngx.re
 local str_format      = core.string.format
@@ -128,11 +127,6 @@ local metadata_schema = {
         log_format = {
             type = "object"
         },
-        max_pending_entries = {
-            type = "integer",
-            description = "maximum number of pending entries in the batch processor",
-            minimum = 1,
-        },
     },
 }
 
@@ -142,7 +136,7 @@ local _M = {
     priority = 413,
     name = plugin_name,
     schema = batch_processor_manager:wrap_schema(schema),
-    metadata_schema = metadata_schema,
+    metadata_schema = batch_processor_manager:wrap_metadata_schema(metadata_schema),
 }
 
 
@@ -340,12 +334,9 @@ end
 
 function _M.log(conf, ctx)
     local index = resolve_index_vars(conf.field.index, ctx.var)
-    local metadata = plugin.plugin_metadata(plugin_name)
-    local max_pending_entries = metadata and metadata.value and
-                                metadata.value.max_pending_entries or nil
     local entry = get_logger_entry(conf, ctx, index)
 
-    if batch_processor_manager:add_entry(conf, entry, max_pending_entries) then
+    if batch_processor_manager:add_entry(conf, entry) then
         return
     end
 
@@ -353,8 +344,7 @@ function _M.log(conf, ctx)
         return send_to_elasticsearch(conf, entries)
     end
 
-    batch_processor_manager:add_entry_to_new_processor(conf, entry, ctx,
-                                                       process, max_pending_entries)
+    batch_processor_manager:add_entry_to_new_processor(conf, entry, ctx, process)
 end
 
 _M._resolve_index_vars = resolve_index_vars
diff --git a/apisix/plugins/google-cloud-logging.lua b/apisix/plugins/google-cloud-logging.lua
index 6133293d250c..1c5af90a0637 100644
--- a/apisix/plugins/google-cloud-logging.lua
+++ b/apisix/plugins/google-cloud-logging.lua
@@ -16,7 +16,6 @@
 --
 
 local core            = require("apisix.core")
-local plugin          = require("apisix.plugin")
 local tostring        = tostring
 local pairs           = pairs
 local http            = require("resty.http")
@@ -117,11 +116,6 @@ local metadata_schema = {
         log_format = {
             type = "object"
         },
-        max_pending_entries = {
-            type = "integer",
-            description = "maximum number of pending entries in the batch processor",
-            minimum = 1,
-        },
     },
 }
 
@@ -245,7 +239,7 @@ local _M = {
     version = 0.1,
     priority = 407,
     name = plugin_name,
-    metadata_schema = metadata_schema,
+    metadata_schema = batch_processor_manager:wrap_metadata_schema(metadata_schema),
     schema = batch_processor_manager:wrap_schema(schema),
 }
 
@@ -260,9 +254,6 @@ end
 
 
 function _M.log(conf, ctx)
-    local metadata = plugin.plugin_metadata(plugin_name)
-    local max_pending_entries = metadata and metadata.value and
-                                metadata.value.max_pending_entries or nil
     local oauth, err = core.lrucache.plugin_ctx(lrucache, ctx, nil,
                                                 create_oauth_object, conf)
     if not oauth then
@@ -272,7 +263,7 @@ function _M.log(conf, ctx)
 
     local entry = get_logger_entry(conf, ctx, oauth)
 
-    if batch_processor_manager:add_entry(conf, entry, max_pending_entries) then
+    if batch_processor_manager:add_entry(conf, entry) then
         return
     end
 
@@ -280,8 +271,7 @@ function _M.log(conf, ctx)
         return send_to_google(oauth, entries)
     end
 
-    batch_processor_manager:add_entry_to_new_processor(conf, entry, ctx,
-                                                       process, max_pending_entries)
+    batch_processor_manager:add_entry_to_new_processor(conf, entry, ctx, process)
 end
 
 
diff --git a/apisix/plugins/http-logger.lua b/apisix/plugins/http-logger.lua
index a57eb3564891..d7b0d4809c27 100644
--- a/apisix/plugins/http-logger.lua
+++ b/apisix/plugins/http-logger.lua
@@ -15,7 +15,6 @@
 -- limitations under the License.
 --
 local bp_manager_mod  = require("apisix.utils.batch-processor-manager")
-local plugin          = require("apisix.plugin")
 local log_util        = require("apisix.utils.log-util")
 local core            = require("apisix.core")
 local http            = require("resty.http")
@@ -25,7 +24,7 @@ local tostring = tostring
 local ipairs   = ipairs
 
 local plugin_name = "http-logger"
-local batch_processor_manager = bp_manager_mod.new("http logger")
+local batch_processor_manager = bp_manager_mod.new("http logger", plugin_name)
 
 local schema = {
     type = "object",
@@ -71,11 +70,6 @@ local metadata_schema = {
         log_format = {
             type = "object"
         },
-        max_pending_entries = {
-            type = "integer",
-            description = "maximum number of pending entries in the batch processor",
-            minimum = 1,
-        },
     },
 }
 
@@ -85,7 +79,7 @@ local _M = {
     priority = 410,
     name = plugin_name,
     schema = batch_processor_manager:wrap_schema(schema),
-    metadata_schema = metadata_schema,
+    metadata_schema = batch_processor_manager:wrap_metadata_schema(metadata_schema),
 }
 
 
@@ -183,16 +177,13 @@ end
 
 
 function _M.log(conf, ctx)
-    local metadata = plugin.plugin_metadata(plugin_name)
-    local max_pending_entries = metadata and metadata.value and
-                                metadata.value.max_pending_entries or nil
     local entry = log_util.get_log_entry(plugin_name, conf, ctx)
 
     if not entry.route_id then
         entry.route_id = "no-matched"
     end
 
-    if batch_processor_manager:add_entry(conf, entry, max_pending_entries) then
+    if batch_processor_manager:add_entry(conf, entry) then
         return
     end
 
@@ -234,7 +225,7 @@ function _M.log(conf, ctx)
         return send_http_data(conf, data)
     end
 
-    batch_processor_manager:add_entry_to_new_processor(conf, entry, ctx, func, max_pending_entries)
+    batch_processor_manager:add_entry_to_new_processor(conf, entry, ctx, func)
 end
 
 
diff --git a/apisix/plugins/kafka-logger.lua b/apisix/plugins/kafka-logger.lua
index b9b254e2faaa..012f842127b0 100644
--- a/apisix/plugins/kafka-logger.lua
+++ b/apisix/plugins/kafka-logger.lua
@@ -18,14 +18,13 @@ local core     = require("apisix.core")
 local log_util = require("apisix.utils.log-util")
 local producer = require ("resty.kafka.producer")
 local bp_manager_mod = require("apisix.utils.batch-processor-manager")
-local plugin = require("apisix.plugin")
 
 local math     = math
 local pairs    = pairs
 local type     = type
 
 local plugin_name = "kafka-logger"
-local batch_processor_manager = bp_manager_mod.new("kafka logger")
+local batch_processor_manager = bp_manager_mod.new("kafka logger", plugin_name)
 
 local lrucache = core.lrucache.new({
     type = "plugin",
@@ -163,11 +162,6 @@ local metadata_schema = {
         log_format = {
             type = "object"
         },
-        max_pending_entries = {
-            type = "integer",
-            description = "maximum number of pending entries in the batch processor",
-            minimum = 1,
-        },
     },
 }
 
@@ -176,7 +170,7 @@ local _M = {
     priority = 403,
     name = plugin_name,
     schema = batch_processor_manager:wrap_schema(schema),
-    metadata_schema = metadata_schema,
+    metadata_schema = batch_processor_manager:wrap_metadata_schema(metadata_schema),
 }
 
 
@@ -252,9 +246,6 @@ end
 
 
 function _M.log(conf, ctx)
-    local metadata = plugin.plugin_metadata(plugin_name)
-    local max_pending_entries = metadata and metadata.value and
-                                metadata.value.max_pending_entries or nil
     local entry
     if conf.meta_format == "origin" then
         entry = log_util.get_req_original(ctx, conf)
@@ -264,7 +255,7 @@ function _M.log(conf, ctx)
         entry = log_util.get_log_entry(plugin_name, conf, ctx)
     end
 
-    if batch_processor_manager:add_entry(conf, entry, max_pending_entries) then
+    if batch_processor_manager:add_entry(conf, entry) then
         return
     end
 
@@ -323,7 +314,7 @@ function _M.log(conf, ctx)
         return send_kafka_data(conf, data, prod)
     end
 
-    batch_processor_manager:add_entry_to_new_processor(conf, entry, ctx, func, max_pending_entries)
+    batch_processor_manager:add_entry_to_new_processor(conf, entry, ctx, func)
 end
 
 
diff --git a/apisix/plugins/lago.lua b/apisix/plugins/lago.lua
index 3c5b1f1664c5..71e83559e388 100644
--- a/apisix/plugins/lago.lua
+++ b/apisix/plugins/lago.lua
@@ -25,7 +25,7 @@ local core            = require("apisix.core")
 local str_format      = core.string.format
 
 local plugin_name = "lago"
-local batch_processor_manager = bp_manager_mod.new("lago logger")
+local batch_processor_manager = bp_manager_mod.new("lago logger", plugin_name)
 
 local schema = {
     type = "object",
@@ -120,15 +120,26 @@ schema = batch_processor_manager:wrap_schema(schema)
 schema.properties.batch_max_size.default = 100
 
 
+local metadata_schema = batch_processor_manager:wrap_metadata_schema({
+    type = "object",
+    properties = {},
+})
+
+
 local _M = {
     version = 0.1,
     priority = 415,
     name = plugin_name,
     schema = schema,
+    metadata_schema = metadata_schema,
 }
 
 
 function _M.check_schema(conf, schema_type)
+    if schema_type == core.schema.TYPE_METADATA then
+        return core.schema.check(metadata_schema, conf)
+    end
+
     local check = {"endpoint_addrs"}
     core.utils.check_https(check, conf, plugin_name)
     core.utils.check_tls_bool({"ssl_verify"}, conf, plugin_name)
diff --git a/apisix/plugins/loggly.lua b/apisix/plugins/loggly.lua
index a0bf9cfac785..ad57438e6110 100644
--- a/apisix/plugins/loggly.lua
+++ b/apisix/plugins/loggly.lua
@@ -159,7 +159,7 @@ local _M = {
     priority = 411,
     name = plugin_name,
     schema = batch_processor_manager:wrap_schema(schema),
-    metadata_schema = metadata_schema
+    metadata_schema = batch_processor_manager:wrap_metadata_schema(metadata_schema)
 }
 
 
diff --git a/apisix/plugins/loki-logger.lua b/apisix/plugins/loki-logger.lua
index c7eb744f4909..9f0828970c23 100644
--- a/apisix/plugins/loki-logger.lua
+++ b/apisix/plugins/loki-logger.lua
@@ -17,7 +17,6 @@
 local bp_manager_mod  = require("apisix.utils.batch-processor-manager")
 local log_util        = require("apisix.utils.log-util")
 local core            = require("apisix.core")
-local plugin          = require("apisix.plugin")
 local http            = require("resty.http")
 local new_tab         = require("table.new")
 
@@ -32,7 +31,7 @@ local ngx          = ngx
 local str_format   = core.string.format
 
 local plugin_name = "loki-logger"
-local batch_processor_manager = bp_manager_mod.new("loki logger")
+local batch_processor_manager = bp_manager_mod.new("loki logger", plugin_name)
 
 local schema = {
     type = "object",
@@ -125,11 +124,6 @@ local metadata_schema = {
         log_format_extra = {
             type = "object"
         },
-        max_pending_entries = {
-            type = "integer",
-            description = "maximum number of pending entries in the batch processor",
-            minimum = 1,
-        },
     },
 }
 
@@ -139,7 +133,7 @@ local _M = {
     priority = 414,
     name = plugin_name,
     schema = batch_processor_manager:wrap_schema(schema),
-    metadata_schema = metadata_schema,
+    metadata_schema = batch_processor_manager:wrap_metadata_schema(metadata_schema),
 }
 
 
@@ -228,9 +222,6 @@ end
 
 
 function _M.log(conf, ctx)
-    local metadata = plugin.plugin_metadata(plugin_name)
-    local max_pending_entries = metadata and metadata.value and
-                                metadata.value.max_pending_entries or nil
     local entry = log_util.get_log_entry(plugin_name, conf, ctx)
 
     if not entry.route_id then
@@ -258,7 +249,7 @@ function _M.log(conf, ctx)
     end
     entry.loki_labels = labels
 
-    if batch_processor_manager:add_entry(conf, entry, max_pending_entries) then
+    if batch_processor_manager:add_entry(conf, entry) then
         return
     end
 
@@ -305,7 +296,7 @@ function _M.log(conf, ctx)
         return send_http_data(conf, data)
     end
 
-    batch_processor_manager:add_entry_to_new_processor(conf, entry, ctx, func, max_pending_entries)
+    batch_processor_manager:add_entry_to_new_processor(conf, entry, ctx, func)
 end
 
 
diff --git a/apisix/plugins/rocketmq-logger.lua b/apisix/plugins/rocketmq-logger.lua
index 9059e9ee2321..a394297d443a 100644
--- a/apisix/plugins/rocketmq-logger.lua
+++ b/apisix/plugins/rocketmq-logger.lua
@@ -15,7 +15,6 @@
 -- limitations under the License.
 --
 local core     = require("apisix.core")
-local plugin   = require("apisix.plugin")
 local log_util = require("apisix.utils.log-util")
 local producer = require ("resty.rocketmq.producer")
 local acl_rpchook = require("resty.rocketmq.acl_rpchook")
@@ -23,7 +22,7 @@ local bp_manager_mod = require("apisix.utils.batch-processor-manager")
 
 local type     = type
 local plugin_name = "rocketmq-logger"
-local batch_processor_manager = bp_manager_mod.new("rocketmq logger")
+local batch_processor_manager = bp_manager_mod.new("rocketmq logger", plugin_name)
 
 local lrucache = core.lrucache.new({
     type = "plugin",
@@ -85,11 +84,6 @@ local metadata_schema = {
         log_format = {
             type = "object"
         },
-        max_pending_entries = {
-            type = "integer",
-            description = "maximum number of pending entries in the batch processor",
-            minimum = 1,
-        },
     },
 }
 
@@ -98,7 +92,7 @@ local _M = {
     priority = 402,
     name = plugin_name,
     schema = batch_processor_manager:wrap_schema(schema),
-    metadata_schema = metadata_schema,
+    metadata_schema = batch_processor_manager:wrap_metadata_schema(metadata_schema),
 }
 
 
@@ -153,9 +147,6 @@ end
 
 
 function _M.log(conf, ctx)
-    local metadata = plugin.plugin_metadata(plugin_name)
-    local max_pending_entries = metadata and metadata.value and
-                                metadata.value.max_pending_entries or nil
     local entry
     if conf.meta_format == "origin" then
         entry = log_util.get_req_original(ctx, conf)
@@ -163,7 +154,7 @@ function _M.log(conf, ctx)
         entry = log_util.get_log_entry(plugin_name, conf, ctx)
     end
 
-    if batch_processor_manager:add_entry(conf, entry, max_pending_entries) then
+    if batch_processor_manager:add_entry(conf, entry) then
         return
     end
 
@@ -201,7 +192,7 @@ function _M.log(conf, ctx)
         return send_rocketmq_data(conf, data, prod)
     end
 
-    batch_processor_manager:add_entry_to_new_processor(conf, entry, ctx, func, max_pending_entries)
+    batch_processor_manager:add_entry_to_new_processor(conf, entry, ctx, func)
 end
 
 
diff --git a/apisix/plugins/skywalking-logger.lua b/apisix/plugins/skywalking-logger.lua
index 712dca9456a7..67d669f04595 100644
--- a/apisix/plugins/skywalking-logger.lua
+++ b/apisix/plugins/skywalking-logger.lua
@@ -15,7 +15,6 @@
 -- limitations under the License.
 --
 local bp_manager_mod  = require("apisix.utils.batch-processor-manager")
-local plugin          = require("apisix.plugin")
 local log_util        = require("apisix.utils.log-util")
 local core            = require("apisix.core")
 local http            = require("resty.http")
@@ -29,7 +28,7 @@ local tostring = tostring
 local tonumber = tonumber
 
 local plugin_name = "skywalking-logger"
-local batch_processor_manager = bp_manager_mod.new("skywalking logger")
+local batch_processor_manager = bp_manager_mod.new("skywalking logger", plugin_name)
 local schema = {
     type = "object",
     properties = {
@@ -71,11 +70,6 @@ local metadata_schema = {
         log_format = {
             type = "object"
         },
-        max_pending_entries = {
-            type = "integer",
-            description = "maximum number of pending entries in the batch processor",
-            minimum = 1,
-        },
     },
 }
 
@@ -85,7 +79,7 @@ local _M = {
     priority = 408,
     name = plugin_name,
     schema = batch_processor_manager:wrap_schema(schema),
-    metadata_schema = metadata_schema,
+    metadata_schema = batch_processor_manager:wrap_metadata_schema(metadata_schema),
 }
 
 
@@ -153,9 +147,6 @@ end
 
 
 function _M.log(conf, ctx)
-    local metadata = plugin.plugin_metadata(plugin_name)
-    local max_pending_entries = metadata and metadata.value and
-                                metadata.value.max_pending_entries or nil
     local log_body = log_util.get_log_entry(plugin_name, conf, ctx)
     local trace_context
     local sw_header = ngx.req.get_headers()["sw8"]
@@ -190,7 +181,7 @@ function _M.log(conf, ctx)
         endpoint = ctx.var.uri,
     }
 
-    if batch_processor_manager:add_entry(conf, entry, max_pending_entries) then
+    if batch_processor_manager:add_entry(conf, entry) then
         return
     end
 
@@ -204,7 +195,7 @@ function _M.log(conf, ctx)
         return send_http_data(conf, data)
     end
 
-    batch_processor_manager:add_entry_to_new_processor(conf, entry, ctx, func, max_pending_entries)
+    batch_processor_manager:add_entry_to_new_processor(conf, entry, ctx, func)
 end
 
 
diff --git a/apisix/plugins/sls-logger.lua b/apisix/plugins/sls-logger.lua
index 65918f2bd8aa..d2fb1cc85286 100644
--- a/apisix/plugins/sls-logger.lua
+++ b/apisix/plugins/sls-logger.lua
@@ -82,7 +82,7 @@ local _M = {
     priority = 406,
     name = plugin_name,
     schema = batch_processor_manager:wrap_schema(schema),
-    metadata_schema = metadata_schema,
+    metadata_schema = batch_processor_manager:wrap_metadata_schema(metadata_schema),
 }
 
 function _M.check_schema(conf,schema_type)
diff --git a/apisix/plugins/splunk-hec-logging.lua b/apisix/plugins/splunk-hec-logging.lua
index ae2f73a1563e..5817f8a46cae 100644
--- a/apisix/plugins/splunk-hec-logging.lua
+++ b/apisix/plugins/splunk-hec-logging.lua
@@ -21,7 +21,6 @@ local ngx_now         = ngx.now
 local http            = require("resty.http")
 local log_util        = require("apisix.utils.log-util")
 local bp_manager_mod  = require("apisix.utils.batch-processor-manager")
-local plugin          = require("apisix.plugin")
 local table_insert    = core.table.insert
 local table_concat    = core.table.concat
 local ipairs          = ipairs
@@ -83,11 +82,6 @@ local metadata_schema = {
         log_format = {
             type = "object"
         },
-        max_pending_entries = {
-            type = "integer",
-            description = "maximum number of pending entries in the batch processor",
-            minimum = 1,
-        }
     },
 }
 
@@ -95,7 +89,7 @@ local _M = {
     version = 0.1,
     priority = 409,
     name = plugin_name,
-    metadata_schema = metadata_schema,
+    metadata_schema = batch_processor_manager:wrap_metadata_schema(metadata_schema),
     schema = batch_processor_manager:wrap_schema(schema),
 }
 
@@ -189,12 +183,9 @@ end
 
 
 function _M.log(conf, ctx)
-    local metadata = plugin.plugin_metadata(plugin_name)
-    local max_pending_entries = metadata and metadata.value and
-                                metadata.value.max_pending_entries or nil
     local entry = get_logger_entry(conf, ctx)
 
-    if batch_processor_manager:add_entry(conf, entry, max_pending_entries) then
+    if batch_processor_manager:add_entry(conf, entry) then
         return
     end
 
@@ -202,8 +193,7 @@ function _M.log(conf, ctx)
         return send_to_splunk(conf, entries)
     end
 
-    batch_processor_manager:add_entry_to_new_processor(conf, entry, ctx,
-                                                        process, max_pending_entries)
+    batch_processor_manager:add_entry_to_new_processor(conf, entry, ctx, process)
 end
 
 
diff --git a/apisix/plugins/syslog.lua b/apisix/plugins/syslog.lua
index 078d2264b823..60124483fb1e 100644
--- a/apisix/plugins/syslog.lua
+++ b/apisix/plugins/syslog.lua
@@ -20,7 +20,7 @@ local bp_manager_mod = require("apisix.utils.batch-processor-manager")
 local syslog = require("apisix.plugins.syslog.init")
 local plugin_name = "syslog"
 
-local batch_processor_manager = bp_manager_mod.new("sys logger")
+local batch_processor_manager = bp_manager_mod.new("sys logger", plugin_name)
 local schema = {
     type = "object",
     properties = {
@@ -76,7 +76,7 @@ local _M = {
     priority = 401,
     name = plugin_name,
     schema = schema,
-    metadata_schema = metadata_schema,
+    metadata_schema = batch_processor_manager:wrap_metadata_schema(metadata_schema),
     flush_syslog = syslog.flush_syslog,
 }
 
diff --git a/apisix/plugins/syslog/init.lua b/apisix/plugins/syslog/init.lua
index 6ca07e7d09a6..15f1eb2b68ab 100644
--- a/apisix/plugins/syslog/init.lua
+++ b/apisix/plugins/syslog/init.lua
@@ -23,7 +23,8 @@ local ipairs = ipairs
 local table_insert = core.table.insert
 local table_concat = core.table.concat
 
-local batch_processor_manager = bp_manager_mod.new("sys logger")
+-- shared by the http and the stream syslog plugin, both named "syslog"
+local batch_processor_manager = bp_manager_mod.new("sys logger", "syslog")
 
 local lrucache = core.lrucache.new({
     ttl = 300, count = 512, serial_creating = true,
diff --git a/apisix/plugins/tcp-logger.lua b/apisix/plugins/tcp-logger.lua
index a52e35b6a995..da64de4549aa 100644
--- a/apisix/plugins/tcp-logger.lua
+++ b/apisix/plugins/tcp-logger.lua
@@ -16,7 +16,6 @@
 --
 local core     = require("apisix.core")
 local log_util = require("apisix.utils.log-util")
-local plugin   = require("apisix.plugin")
 local bp_manager_mod = require("apisix.utils.batch-processor-manager")
 local plugin_name = "tcp-logger"
 local tostring = tostring
@@ -24,7 +23,7 @@ local ngx = ngx
 local tcp = ngx.socket.tcp
 
 
-local batch_processor_manager = bp_manager_mod.new("tcp logger")
+local batch_processor_manager = bp_manager_mod.new("tcp logger", plugin_name)
 local schema = {
     type = "object",
     properties = {
@@ -66,11 +65,6 @@ local metadata_schema = {
         log_format = {
             type = "object"
         },
-        max_pending_entries = {
-            type = "integer",
-            description = "maximum number of pending entries in the batch processor",
-            minimum = 1,
-        },
     },
 }
 
@@ -78,7 +72,7 @@ local _M = {
     version = 0.1,
     priority = 405,
     name = plugin_name,
-    metadata_schema = metadata_schema,
+    metadata_schema = batch_processor_manager:wrap_metadata_schema(metadata_schema),
     schema = batch_processor_manager:wrap_schema(schema),
 }
 
@@ -146,12 +140,9 @@ end
 
 
 function _M.log(conf, ctx)
-    local metadata = plugin.plugin_metadata(plugin_name)
-    local max_pending_entries = metadata and metadata.value and
-                                metadata.value.max_pending_entries or nil
     local entry = log_util.get_log_entry(plugin_name, conf, ctx)
 
-    if batch_processor_manager:add_entry(conf, entry, max_pending_entries) then
+    if batch_processor_manager:add_entry(conf, entry) then
         return
     end
 
@@ -171,7 +162,7 @@ function _M.log(conf, ctx)
         return send_tcp_data(conf, data)
     end
 
-    batch_processor_manager:add_entry_to_new_processor(conf, entry, ctx, func, max_pending_entries)
+    batch_processor_manager:add_entry_to_new_processor(conf, entry, ctx, func)
 end
 
 
diff --git a/apisix/plugins/tencent-cloud-cls.lua b/apisix/plugins/tencent-cloud-cls.lua
index 9e176b370051..18f0cd434f71 100644
--- a/apisix/plugins/tencent-cloud-cls.lua
+++ b/apisix/plugins/tencent-cloud-cls.lua
@@ -16,7 +16,6 @@
 --
 
 local core = require("apisix.core")
-local plugin = require("apisix.plugin")
 local log_util = require("apisix.utils.log-util")
 local bp_manager_mod = require("apisix.utils.batch-processor-manager")
 local cls_sdk = require("apisix.plugins.tencent-cloud-cls.cls-sdk")
@@ -77,11 +76,6 @@ local metadata_schema = {
         log_format = {
             type = "object"
         },
-        max_pending_entries = {
-            type = "integer",
-            description = "maximum number of pending entries in the batch processor",
-            minimum = 1,
-        },
     },
 }
 
@@ -91,7 +85,7 @@ local _M = {
     priority = 397,
     name = plugin_name,
     schema = batch_processor_manager:wrap_schema(schema),
-    metadata_schema = metadata_schema,
+    metadata_schema = batch_processor_manager:wrap_metadata_schema(metadata_schema),
 }
 
 
@@ -129,9 +123,6 @@ end
 
 
 function _M.log(conf, ctx)
-    local metadata = plugin.plugin_metadata(plugin_name)
-    local max_pending_entries = metadata and metadata.value and
-                                metadata.value.max_pending_entries or nil
     -- sample if set
     if not ctx.cls_sample then
         core.log.debug("cls not sampled, skip log")
@@ -146,7 +137,7 @@ function _M.log(conf, ctx)
         end
     end
 
-    if batch_processor_manager:add_entry(conf, entry, max_pending_entries) then
+    if batch_processor_manager:add_entry(conf, entry) then
         return
     end
 
@@ -162,8 +153,7 @@ function _M.log(conf, ctx)
         return sdk:send_to_cls(entries)
     end
 
-    batch_processor_manager:add_entry_to_new_processor(conf, entry, ctx,
-                                                        process, max_pending_entries)
+    batch_processor_manager:add_entry_to_new_processor(conf, entry, ctx, process)
 end
 
 
diff --git a/apisix/plugins/udp-logger.lua b/apisix/plugins/udp-logger.lua
index ae8b626942f2..79fe691f8890 100644
--- a/apisix/plugins/udp-logger.lua
+++ b/apisix/plugins/udp-logger.lua
@@ -16,7 +16,6 @@
 --
 local core = require("apisix.core")
 local log_util = require("apisix.utils.log-util")
-local plugin = require("apisix.plugin")
 local bp_manager_mod = require("apisix.utils.batch-processor-manager")
 local plugin_name = "udp-logger"
 local tostring = tostring
@@ -24,7 +23,7 @@ local ngx = ngx
 local udp = ngx.socket.udp
 
 
-local batch_processor_manager = bp_manager_mod.new("udp logger")
+local batch_processor_manager = bp_manager_mod.new("udp logger", plugin_name)
 local schema = {
     type = "object",
     properties = {
@@ -64,11 +63,6 @@ local metadata_schema = {
         log_format = {
             type = "object"
         },
-        max_pending_entries = {
-            type = "integer",
-            description = "maximum number of pending entries in the batch processor",
-            minimum = 1,
-        },
     },
 }
 
@@ -76,7 +70,7 @@ local _M = {
     version = 0.1,
     priority = 400,
     name = plugin_name,
-    metadata_schema = metadata_schema,
+    metadata_schema = batch_processor_manager:wrap_metadata_schema(metadata_schema),
     schema = batch_processor_manager:wrap_schema(schema),
 }
 
@@ -131,12 +125,9 @@ end
 
 
 function _M.log(conf, ctx)
-    local metadata = plugin.plugin_metadata(plugin_name)
-    local max_pending_entries = metadata and metadata.value and
-                                metadata.value.max_pending_entries or nil
     local entry = log_util.get_log_entry(plugin_name, conf, ctx)
 
-    if batch_processor_manager:add_entry(conf, entry, max_pending_entries) then
+    if batch_processor_manager:add_entry(conf, entry) then
         return
     end
 
@@ -156,7 +147,7 @@ function _M.log(conf, ctx)
         return send_udp_data(conf, data)
     end
 
-    batch_processor_manager:add_entry_to_new_processor(conf, entry, ctx, func, max_pending_entries)
+    batch_processor_manager:add_entry_to_new_processor(conf, entry, ctx, func)
 end
 
 return _M
diff --git a/apisix/stream/plugins/syslog.lua b/apisix/stream/plugins/syslog.lua
index 5a44ce425786..da67d8c6a78b 100644
--- a/apisix/stream/plugins/syslog.lua
+++ b/apisix/stream/plugins/syslog.lua
@@ -21,7 +21,7 @@ local bp_manager_mod = require("apisix.utils.batch-processor-manager")
 local syslog = require("apisix.plugins.syslog.init")
 local plugin_name = "syslog"
 
-local batch_processor_manager = bp_manager_mod.new("stream sys logger")
+local batch_processor_manager = bp_manager_mod.new("stream sys logger", plugin_name)
 local schema = {
     type = "object",
     properties = {
@@ -54,7 +54,7 @@ local _M = {
     priority = 401,
     name = plugin_name,
     schema = schema,
-    metadata_schema = metadata_schema,
+    metadata_schema = batch_processor_manager:wrap_metadata_schema(metadata_schema),
     flush_syslog = syslog.flush_syslog,
 }
 
diff --git a/apisix/utils/batch-processor-manager.lua b/apisix/utils/batch-processor-manager.lua
index 5ff594c0568b..74da9d78c60b 100644
--- a/apisix/utils/batch-processor-manager.lua
+++ b/apisix/utils/batch-processor-manager.lua
@@ -18,21 +18,39 @@ local core = require("apisix.core")
 local plugin = require("apisix.plugin")
 local batch_processor = require("apisix.utils.batch-processor")
 local timer_at = ngx.timer.at
+local now = ngx.now
 local pairs = pairs
 local setmetatable = setmetatable
 
 
+-- A pending entry keeps a whole log payload alive, including the request and
+-- response bodies when body logging is on, so a log server that is slow or
+-- unreachable turns the backlog into unbounded worker memory. Cap it by default;
+-- the batch-processor documentation records what the cap costs per body size.
+local DEFAULT_MAX_PENDING_ENTRIES = 8192
+-- Logging one line per discarded entry would itself become a flood during the very
+-- outage that causes the discards, so report a summary at most this often, in seconds.
+local DISCARD_LOG_INTERVAL = 1
+
+
 local _M = {}
 local mt = { __index = _M }
 
 
-function _M.new(name)
+-- `name` labels the batch processor in logs and metrics and is not necessarily the
+-- plugin's name; `plugin_name` names the plugin whose metadata carries
+-- `max_pending_entries`, and defaults to `name`.
+function _M.new(name, plugin_name)
     return setmetatable({
         stale_timer_running = false,
         buffers = {},
         total_pushed_entries = 0,
         total_stale_processed_entries = 0,
+        processed_entries_snapshot = 0,
+        discarded_entries = 0,
+        last_discard_log_time = 0,
         name = name,
+        plugin_name = plugin_name or name,
     }, mt)
 end
 
@@ -52,6 +70,20 @@ function _M:wrap_schema(schema)
 end
 
 
+-- Every batch-processor based logger exposes the same backlog limit, so declare it
+-- here instead of repeating it in each plugin's metadata schema.
+function _M:wrap_metadata_schema(schema)
+    schema.properties.max_pending_entries = {
+        type = "integer",
+        minimum = 1,
+        default = DEFAULT_MAX_PENDING_ENTRIES,
+        description = "maximum number of entries waiting to be processed; new "
+                   .. "entries are discarded while the backlog exceeds it",
+    }
+    return schema
+end
+
+
 -- remove stale objects from the memory after timer expires
 local function remove_stale_objects(premature, self)
     if premature then
@@ -98,16 +130,52 @@ local function total_processed_entries(self)
     return processed_entries
 end
 
-function _M:add_entry(conf, entry, max_pending_entries)
-    if max_pending_entries then
-        local total_processed_entries_count = total_processed_entries(self)
-        if self.total_pushed_entries - total_processed_entries_count > max_pending_entries then
-            core.log.error("max pending entries limit exceeded. discarding entry.",
-                           " total_pushed_entries: ", self.total_pushed_entries,
-                           " total_processed_entries: ", total_processed_entries_count,
-                           " max_pending_entries: ", max_pending_entries)
-            return
-        end
+
+local function max_pending_entries(self)
+    local metadata = plugin.plugin_metadata(self.plugin_name)
+    return metadata and metadata.value and metadata.value.max_pending_entries
+           or DEFAULT_MAX_PENDING_ENTRIES
+end
+
+
+-- The processed count only ever grows, so the last one we read is a lower bound on
+-- the current one, and `pushed - snapshot` is therefore an upper bound on the
+-- backlog. While that bound is under the limit the backlog certainly is too, which
+-- keeps the common path off the per-buffer walk: the walk only happens once the
+-- bound catches up with the limit, roughly once every `max_pending_entries` entries.
+local function backlog_is_full(self, limit)
+    if self.total_pushed_entries - self.processed_entries_snapshot < limit then
+        return false
+    end
+
+    self.processed_entries_snapshot = total_processed_entries(self)
+    return self.total_pushed_entries - self.processed_entries_snapshot >= limit
+end
+
+
+local function report_discard(self, limit)
+    self.discarded_entries = self.discarded_entries + 1
+
+    local time = now()
+    if time - self.last_discard_log_time < DISCARD_LOG_INTERVAL then
+        return
+    end
+
+    core.log.error("max pending entries limit exceeded. discarding entry.",
+                   " total_pushed_entries: ", self.total_pushed_entries,
+                   " total_processed_entries: ", self.processed_entries_snapshot,
+                   " max_pending_entries: ", limit,
+                   " discarded_entries: ", self.discarded_entries)
+    self.last_discard_log_time = time
+    self.discarded_entries = 0
+end
+
+
+function _M:add_entry(conf, entry)
+    local limit = max_pending_entries(self)
+    if backlog_is_full(self, limit) then
+        report_discard(self, limit)
+        return
     end
     check_stale(self)
 
@@ -122,16 +190,12 @@ function _M:add_entry(conf, entry, max_pending_entries)
 end
 
 
-function _M:add_entry_to_new_processor(conf, entry, ctx, func, max_pending_entries)
-    if max_pending_entries then
-        local total_processed_entries_count = total_processed_entries(self)
-        if self.total_pushed_entries - total_processed_entries_count > max_pending_entries then
-            core.log.error("max pending entries limit exceeded. discarding entry.",
-                           " total_pushed_entries: ", self.total_pushed_entries,
-                           " total_processed_entries: ", total_processed_entries_count,
-                           " max_pending_entries: ", max_pending_entries)
-            return
-        end
+function _M:add_entry_to_new_processor(conf, entry, ctx, func)
+    -- Callers reach this only after add_entry() declined, so a discarded entry has
+    -- already been counted and reported there; re-check the backlog so a direct
+    -- caller is still bounded, but do not count the same entry a second time.
+    if backlog_is_full(self, max_pending_entries(self)) then
+        return
     end
     check_stale(self)
 
diff --git a/docs/en/latest/batch-processor.md b/docs/en/latest/batch-processor.md
index 48c1a9d39ac6..d06f239a3358 100644
--- a/docs/en/latest/batch-processor.md
+++ b/docs/en/latest/batch-processor.md
@@ -39,6 +39,29 @@ or when the buffer duration exceeds.
 | max_retry_count  | integer | optional    | 0       | [0,...] | Maximum number of retries before removing the entry from the processing pipeline when an error occurs. |
 | retry_delay      | integer | optional    | 1       | [0,...] | Number of seconds the process execution should be delayed if the execution fails. |
 
+## Limiting the backlog
+
+Entries that have been buffered but not yet delivered are held in the worker's memory. When the log server is slow or unreachable, entries arrive faster than they leave and the backlog — along with the worker's memory — grows with the request rate.
+
+Every logger built on the batch processor therefore accepts a `max_pending_entries` limit through its [plugin metadata](./terminology/plugin-metadata.md), which defaults to `8192`. While the backlog exceeds the limit, new entries are discarded and a summary is written to the error log at most once per second:
+
+```text
+max pending entries limit exceeded. discarding entry. total_pushed_entries: 12289 total_processed_entries: 4096 max_pending_entries: 8192 discarded_entries: 3172
+```
+
+The limit counts entries, so what it costs in memory depends on how large each entry is — above all on whether `include_req_body` and `include_resp_body` are enabled and how large those bodies are. The figures below are the peak growth in a worker's resident memory while its log server accepted connections but never answered, measured with `http-logger`, both bodies logged, and otherwise stock batch processor settings:
+
+| Body logged per request | Peak worker memory at the default limit |
+|-------------------------|-----------------------------------------|
+| bodies not logged       | ~40 MB |
+| 1 KB request + 1 KB response | ~100 MB |
+| 4 KB request + 4 KB response | ~250 MB |
+| 16 KB request + 16 KB response | ~840 MB |
+
+The cost grows roughly in proportion to the body size, so lower `max_pending_entries` if you log bodies larger than a few KB. The figures are higher than the entries alone would account for because batches already handed to the sender hold both their entries and the serialized payload built from them.
+
+The limit only comes into play when delivery falls behind. With a log server that keeps up, the backlog stays close to `batch_max_size` — under 1000 entries at 3000 requests per second in the same setup — so the default leaves about eight times the room healthy operation needs. Raising `batch_max_size` raises the healthy backlog with it, so raise `max_pending_entries` too if you do.
+
 The following code shows an example of how to use batch processor in your plugin:
 
 ```lua
@@ -46,12 +69,17 @@ local bp_manager_mod = require("apisix.utils.batch-processor-manager")
 ...
 
 local plugin_name = "xxx-logger"
-local batch_processor_manager = bp_manager_mod.new(plugin_name)
+-- the second argument names the plugin whose metadata carries max_pending_entries,
+-- and is only needed when the batch processor's own name differs from it
+local batch_processor_manager = bp_manager_mod.new("xxx logger", plugin_name)
 local schema = {...}
+local metadata_schema = {...}
 local _M = {
     ...
     name = plugin_name,
     schema = batch_processor_manager:wrap_schema(schema),
+    -- adds max_pending_entries to the plugin's metadata schema
+    metadata_schema = batch_processor_manager:wrap_metadata_schema(metadata_schema),
 }
 
 ...
diff --git a/docs/en/latest/plugins/clickhouse-logger.md b/docs/en/latest/plugins/clickhouse-logger.md
index 5b530bc38f77..ef95a7ee40d7 100644
--- a/docs/en/latest/plugins/clickhouse-logger.md
+++ b/docs/en/latest/plugins/clickhouse-logger.md
@@ -73,7 +73,7 @@ This Plugin supports using batch processors to aggregate and process entries (lo
 |--------------------|---------|----------|---------|--------------|---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
 | log_format         | object  | False    |         |              | Custom log format using key-value pairs in JSON format. Values can reference [APISIX variables](../apisix-variable.md) or [NGINX variables](https://nginx.org/en/docs/http/ngx_http_core_module.html) by prefixing with `$`. This configuration is global and applies to all Routes and Services that use the `clickhouse-logger` Plugin. |
 | log_format_extra         | object  | False    |         |              | Extra log fields **added on top of** the default log entry, keeping every default field instead of replacing them (unlike `log_format`). Same value syntax as `log_format`. Ignored when `log_format` is set. |
-| max_pending_entries | integer | False   |         | >= 1         | Maximum number of unprocessed entries allowed in the batch processor. When this limit is reached, new entries will be dropped until the backlog is reduced.                                                                                                                      |
+| max_pending_entries | integer | False | 8192 | >= 1 | Maximum number of entries waiting to be processed. New entries are discarded while the backlog exceeds this, which stops a slow or unreachable log server from growing the worker's memory without bound. See [Batch Processor](../batch-processor.md#limiting-the-backlog) for the memory a backlog of this size costs. |
 
 ## Examples
 
diff --git a/docs/en/latest/plugins/datadog.md b/docs/en/latest/plugins/datadog.md
index e5bd330e5a23..c282c92fffb3 100644
--- a/docs/en/latest/plugins/datadog.md
+++ b/docs/en/latest/plugins/datadog.md
@@ -63,6 +63,7 @@ You can configure the Plugin through Plugin metadata.
 | port          | integer | False    | 8125                | DogStatsD server port.                                                                                                                    |
 | namespace     | string  | False    | "apisix"            | Prefix for all custom metrics sent by the APISIX agent. Useful for finding entities for metrics graph. For example, `apisix.request.counter`. |
 | constant_tags | array   | False    | [ "source:apisix" ] | Static tags to embed into generated metrics. Useful for grouping metrics over certain signals. See [defining tags](https://docs.datadoghq.com/getting_started/tagging/#defining-tags) for more. |
+| max_pending_entries | integer | False | 8192 | Maximum number of entries waiting to be processed. New entries are discarded while the backlog exceeds this, which stops a slow or unreachable log server from growing the worker's memory without bound. See [Batch Processor](../batch-processor.md#limiting-the-backlog) for the memory a backlog of this size costs. |
 
 ## Metrics
 
diff --git a/docs/en/latest/plugins/elasticsearch-logger.md b/docs/en/latest/plugins/elasticsearch-logger.md
index a6c15f14af7c..d4ea6c4fb8d2 100644
--- a/docs/en/latest/plugins/elasticsearch-logger.md
+++ b/docs/en/latest/plugins/elasticsearch-logger.md
@@ -67,7 +67,7 @@ This Plugin supports using batch processors to aggregate and process entries (lo
 |------|------|----------|---------|-------------|
 | log_format | object | False |  | Log format declared as key-value pairs in JSON. Values support strings and nested objects (up to five levels deep; deeper fields are truncated). Within strings, [APISIX](../apisix-variable.md) or [NGINX](http://nginx.org/en/docs/varindex.html) variables can be referenced by prefixing with `$`. |
 | log_format_extra | object | False |  | Extra log fields **added on top of** the default log entry, keeping every default field instead of replacing them (unlike `log_format`). Same value syntax as `log_format`. Ignored when `log_format` is set. |
-| max_pending_entries | integer | False | | Maximum number of pending entries that can be buffered in batch processor before it starts dropping them. |
+| max_pending_entries | integer | False | 8192 | Maximum number of entries waiting to be processed. New entries are discarded while the backlog exceeds this, which stops a slow or unreachable log server from growing the worker's memory without bound. See [Batch Processor](../batch-processor.md#limiting-the-backlog) for the memory a backlog of this size costs. |
 
 ## Examples
 
diff --git a/docs/en/latest/plugins/google-cloud-logging.md b/docs/en/latest/plugins/google-cloud-logging.md
index 0e1b4736498b..0518a853fa8f 100644
--- a/docs/en/latest/plugins/google-cloud-logging.md
+++ b/docs/en/latest/plugins/google-cloud-logging.md
@@ -68,7 +68,7 @@ This Plugin supports using batch processors to aggregate and process entries (lo
 |--------------------|---------|----------|---------|--------------|---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
 | log_format         | object  | False    |         |              | Custom log format using key-value pairs in JSON format. Values can reference [APISIX variables](../apisix-variable.md) or [NGINX variables](https://nginx.org/en/docs/http/ngx_http_core_module.html) by prefixing with `$`. This configuration is global and applies to all Routes and Services that use the `google-cloud-logging` Plugin. |
 | log_format_extra         | object  | False    |         |              | Extra log fields **added on top of** the default log entry, keeping every default field instead of replacing them (unlike `log_format`). Same value syntax as `log_format`. Ignored when `log_format` is set. |
-| max_pending_entries | integer | False   |         | >= 1         | Maximum number of unprocessed entries allowed in the batch processor. When this limit is reached, new entries will be dropped until the backlog is reduced.                                                                                                                      |
+| max_pending_entries | integer | False | 8192 | >= 1 | Maximum number of entries waiting to be processed. New entries are discarded while the backlog exceeds this, which stops a slow or unreachable log server from growing the worker's memory without bound. See [Batch Processor](../batch-processor.md#limiting-the-backlog) for the memory a backlog of this size costs. |
 
 ## Examples
 
diff --git a/docs/en/latest/plugins/http-logger.md b/docs/en/latest/plugins/http-logger.md
index c511f3f2f769..4f26a3dcde74 100644
--- a/docs/en/latest/plugins/http-logger.md
+++ b/docs/en/latest/plugins/http-logger.md
@@ -63,12 +63,11 @@ This Plugin supports using batch processors to aggregate and process entries (lo
 
 You can also set the format of the logs by configuring the Plugin metadata. The following configurations are available:
 
-| Name                | Type    | Required | Description                                                                                                                                                                                                     |
-|---------------------|---------|----------|-----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
-| log_format          | object  | False    | Custom log format using key-value pairs in JSON format. Values can reference [NGINX variables](https://nginx.org/en/docs/http/ngx_http_core_module.html).                                                       |
-| log_format_extra          | object  | False    | Extra log fields **added on top of** the default log entry, keeping every default field instead of replacing them (unlike `log_format`). Same value syntax as `log_format`. Ignored when `log_format` is set. |
-| max_pending_entries | integer | False    | Maximum number of unprocessed entries allowed in the batch processor. When this limit is reached, new entries will be dropped until the backlog is reduced. Available in APISIX from version 3.15.0.            |
-
+| Name                | Type    | Required | Default | Description                                                                                                                                                                                                     |
+|---------------------|---------|----------|---------|-----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
+| log_format          | object  | False    |         | Custom log format using key-value pairs in JSON format. Values can reference [NGINX variables](https://nginx.org/en/docs/http/ngx_http_core_module.html).                                                       |
+| log_format_extra          | object  | False    |         | Extra log fields **added on top of** the default log entry, keeping every default field instead of replacing them (unlike `log_format`). Same value syntax as `log_format`. Ignored when `log_format` is set. |
+| max_pending_entries | integer | False | 8192 | Maximum number of entries waiting to be processed. New entries are discarded while the backlog exceeds this, which stops a slow or unreachable log server from growing the worker's memory without bound. See [Batch Processor](../batch-processor.md#limiting-the-backlog) for the memory a backlog of this size costs. |
 :::info IMPORTANT
 
 Configuring the Plugin metadata is global in scope. This means that it will take effect on all Routes and Services which use the `http-logger` Plugin.
diff --git a/docs/en/latest/plugins/kafka-logger.md b/docs/en/latest/plugins/kafka-logger.md
index 22ecb3c3fb59..61081bca6778 100644
--- a/docs/en/latest/plugins/kafka-logger.md
+++ b/docs/en/latest/plugins/kafka-logger.md
@@ -148,8 +148,7 @@ You can also set the format of the logs by configuring the Plugin metadata. The
 | ------------------- | ------- | -------- | ------- | ------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- |
 | log_format          | object  | False    |         | Log format declared as key-value pairs in JSON. Values support strings and nested objects (up to five levels deep; deeper fields are truncated). Within strings, [APISIX](../apisix-variable.md) or [NGINX](http://nginx.org/en/docs/varindex.html) variables can be referenced by prefixing with `$`. |
 | log_format_extra          | object  | False    |         | Extra log fields **added on top of** the default log entry, keeping every default field instead of replacing them (unlike `log_format`). Same value syntax as `log_format`. Ignored when `log_format` is set. |
-| max_pending_entries | integer | False    |         | Maximum number of pending entries that can be buffered in the batch processor before it starts dropping them.                                                                                                                                           |
-
+| max_pending_entries | integer | False | 8192 | Maximum number of entries waiting to be processed. New entries are discarded while the backlog exceeds this, which stops a slow or unreachable log server from growing the worker's memory without bound. See [Batch Processor](../batch-processor.md#limiting-the-backlog) for the memory a backlog of this size costs. |
 :::info IMPORTANT
 
 Configuring the Plugin metadata is global in scope. This means that it will take effect on all Routes and Services which use the `kafka-logger` Plugin.
diff --git a/docs/en/latest/plugins/lago.md b/docs/en/latest/plugins/lago.md
index c2b445f29535..dd503ed55ca6 100644
--- a/docs/en/latest/plugins/lago.md
+++ b/docs/en/latest/plugins/lago.md
@@ -66,6 +66,12 @@ When enabled, the plugin will collect information from the request context (e.g.
 
 This Plugin supports using batch processors to aggregate and process events in a batch. This avoids the need for frequently submitting the data. The batch processor submits data every `5` seconds or when the data in the queue reaches `1000`. See [Batch Processor](../batch-processor.md#configuration) for more information or setting your custom configuration.
 
+## Plugin Metadata
+
+| Name | Type | Required | Default | Description |
+|------|------|----------|---------|-------------|
+| max_pending_entries | integer | False | 8192 | Maximum number of entries waiting to be processed. New entries are discarded while the backlog exceeds this, which stops a slow or unreachable Lago service from growing the worker's memory without bound. See [Batch Processor](../batch-processor.md#limiting-the-backlog) for the memory a backlog of this size costs. |
+
 ## Examples
 
 The examples below demonstrate how you can configure `lago` Plugin for typical scenario.
diff --git a/docs/en/latest/plugins/loggly.md b/docs/en/latest/plugins/loggly.md
index e672f9fcbab2..60e46371e816 100644
--- a/docs/en/latest/plugins/loggly.md
+++ b/docs/en/latest/plugins/loggly.md
@@ -74,6 +74,7 @@ You can also configure the Plugin through Plugin metadata. The following configu
 | protocol   | string  | False    | "syslog"             | [ "syslog" , "http", "https" ] | Protocol in which the logs are sent to Loggly.                                                                                                                                                                                 |
 | log_format | object  | False    | nil                  |                                | Log format declared as key-value pairs in JSON. Values support strings and nested objects (up to five levels deep; deeper fields are truncated). Within strings, [APISIX](../apisix-variable.md) or [NGINX](http://nginx.org/en/docs/varindex.html) variables can be referenced by prefixing with `$`. |
 | log_format_extra | object  | False    |                      |                                | Extra log fields **added on top of** the default log entry, keeping every default field instead of replacing them (unlike `log_format`). Same value syntax as `log_format`. Ignored when `log_format` is set. |
+| max_pending_entries | integer | False | 8192 | >= 1 | Maximum number of entries waiting to be processed. New entries are discarded while the backlog exceeds this, which stops a slow or unreachable log server from growing the worker's memory without bound. See [Batch Processor](../batch-processor.md#limiting-the-backlog) for the memory a backlog of this size costs. |
 
 We support [Syslog](https://documentation.solarwinds.com/en/success_center/loggly/content/admin/streaming-syslog-without-using-files.htm), [HTTP/S](https://documentation.solarwinds.com/en/success_center/loggly/content/admin/http-bulk-endpoint.htm) (bulk endpoint) protocols to send log events to Loggly. By default, in APISIX side, the protocol is set to "syslog". It lets you send RFC5424 compliant syslog events with some fine-grained control (log severity mapping based on upstream HTTP response code). But HTTP/S bulk endpoint is great to send larger batches of log events with faster transmission speed. If you wish to update it, just update the metadata.
 
diff --git a/docs/en/latest/plugins/loki-logger.md b/docs/en/latest/plugins/loki-logger.md
index 6b7bd6c93c04..43e052a1b6c2 100644
--- a/docs/en/latest/plugins/loki-logger.md
+++ b/docs/en/latest/plugins/loki-logger.md
@@ -72,7 +72,7 @@ You can also configure log format on a global scale using the [Plugin Metadata](
 |------|------|----------|---------|--------------|-------------|
 | log_format | object | False |  |  | Custom log format as key-value pairs in JSON. Setting this **replaces** the default log entry with a flat custom format. Values support strings and nested objects (up to five levels deep; deeper fields are truncated). Within strings, [APISIX variables](../apisix-variable.md) and [NGINX variables](http://nginx.org/en/docs/varindex.html) can be referenced by prefixing with `$`. |
 | log_format_extra | object | False |  |  | Extra log fields **added on top of** the default log entry, keeping every default field instead of replacing them (unlike `log_format`). Same value syntax as `log_format`. Ignored when `log_format` is set. |
-| max_pending_entries | integer | False | |  | Maximum number of pending entries that can be buffered in batch processor before it starts dropping them. |
+| max_pending_entries | integer | False | 8192 | >= 1 | Maximum number of entries waiting to be processed. New entries are discarded while the backlog exceeds this, which stops a slow or unreachable log server from growing the worker's memory without bound. See [Batch Processor](../batch-processor.md#limiting-the-backlog) for the memory a backlog of this size costs. |
 
 ## Examples
 
diff --git a/docs/en/latest/plugins/rocketmq-logger.md b/docs/en/latest/plugins/rocketmq-logger.md
index 2b3d2a927122..02aa93d34176 100644
--- a/docs/en/latest/plugins/rocketmq-logger.md
+++ b/docs/en/latest/plugins/rocketmq-logger.md
@@ -68,12 +68,11 @@ NOTE: `encrypt_fields = {"secret_key"}` is also defined in the schema, which mea
 
 You can also set the format of the logs by configuring the Plugin metadata. The following configurations are available:
 
-| Name                | Type    | Required | Description                                                                                                                                                                                                     |
-|---------------------|---------|----------|-----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
-| log_format          | object  | False    | Custom log format using key-value pairs in JSON format. Values can reference [NGINX variables](https://nginx.org/en/docs/http/ngx_http_core_module.html).                                                       |
-| log_format_extra          | object  | False    | Extra log fields **added on top of** the default log entry, keeping every default field instead of replacing them (unlike `log_format`). Same value syntax as `log_format`. Ignored when `log_format` is set. |
-| max_pending_entries | integer | False    | Maximum number of unprocessed entries allowed in the batch processor. When this limit is reached, new entries will be dropped until the backlog is reduced. Available in APISIX from version 3.15.0.            |
-
+| Name                | Type    | Required | Default | Description                                                                                                                                                                                                     |
+|---------------------|---------|----------|---------|-----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
+| log_format          | object  | False    |         | Custom log format using key-value pairs in JSON format. Values can reference [NGINX variables](https://nginx.org/en/docs/http/ngx_http_core_module.html).                                                       |
+| log_format_extra          | object  | False    |         | Extra log fields **added on top of** the default log entry, keeping every default field instead of replacing them (unlike `log_format`). Same value syntax as `log_format`. Ignored when `log_format` is set. |
+| max_pending_entries | integer | False | 8192 | Maximum number of entries waiting to be processed. New entries are discarded while the backlog exceeds this, which stops a slow or unreachable log server from growing the worker's memory without bound. See [Batch Processor](../batch-processor.md#limiting-the-backlog) for the memory a backlog of this size costs. |
 :::info IMPORTANT
 
 Configuring the Plugin metadata is global in scope. This means that it will take effect on all Routes and Services which use the `rocketmq-logger` Plugin.
diff --git a/docs/en/latest/plugins/skywalking-logger.md b/docs/en/latest/plugins/skywalking-logger.md
index d61589e7faff..f527bdf854e6 100644
--- a/docs/en/latest/plugins/skywalking-logger.md
+++ b/docs/en/latest/plugins/skywalking-logger.md
@@ -66,7 +66,7 @@ You can also set the format of the logs by configuring the Plugin metadata. The
 | ---------- | ------ | -------- | ----------------------------------------------------------------------------- | ------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- |
 | log_format | object | False    |  | Custom log format as key-value pairs in JSON. Values support strings and nested objects (up to five levels deep; deeper fields are truncated). Within strings, [APISIX](../apisix-variable.md) or [NGINX variables](http://nginx.org/en/docs/varindex.html) can be referenced by prefixing with `$`. |
 | log_format_extra | object | False    |  | Extra log fields **added on top of** the default log entry, keeping every default field instead of replacing them (unlike `log_format`). Same value syntax as `log_format`. Ignored when `log_format` is set. |
-| max_pending_entries | integer | False | | Maximum number of pending entries that can be buffered in batch processor before it starts dropping them. |
+| max_pending_entries | integer | False | 8192 | Maximum number of entries waiting to be processed. New entries are discarded while the backlog exceeds this, which stops a slow or unreachable log server from growing the worker's memory without bound. See [Batch Processor](../batch-processor.md#limiting-the-backlog) for the memory a backlog of this size costs. |
 
 ## Examples
 
diff --git a/docs/en/latest/plugins/sls-logger.md b/docs/en/latest/plugins/sls-logger.md
index cd53f5efcec2..1ccfadc1573e 100644
--- a/docs/en/latest/plugins/sls-logger.md
+++ b/docs/en/latest/plugins/sls-logger.md
@@ -94,6 +94,7 @@ You can also set the format of the logs by configuring the Plugin metadata. The
 | ---------- | ------ | -------- | ----------------------------------------------------------------------------- | ------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- |
 | log_format | object | False    |  | Log format declared as key-value pairs in JSON. Values support strings and nested objects (up to five levels deep; deeper fields are truncated). Within strings, [APISIX](../apisix-variable.md) or [NGINX](http://nginx.org/en/docs/varindex.html) variables can be referenced by prefixing with `$`. |
 | log_format_extra | object | False    |  | Extra log fields **added on top of** the default log entry, keeping every default field instead of replacing them (unlike `log_format`). Same value syntax as `log_format`. Ignored when `log_format` is set. |
+| max_pending_entries | integer | False | 8192 | Maximum number of entries waiting to be processed. New entries are discarded while the backlog exceeds this, which stops a slow or unreachable log server from growing the worker's memory without bound. See [Batch Processor](../batch-processor.md#limiting-the-backlog) for the memory a backlog of this size costs. |
 
 :::info IMPORTANT
 
diff --git a/docs/en/latest/plugins/splunk-hec-logging.md b/docs/en/latest/plugins/splunk-hec-logging.md
index 6ebab57ce64e..df3c5e2c4e3d 100644
--- a/docs/en/latest/plugins/splunk-hec-logging.md
+++ b/docs/en/latest/plugins/splunk-hec-logging.md
@@ -64,7 +64,7 @@ This Plugin supports using batch processors to aggregate and process entries (lo
 |--------------------|---------|----------|---------|--------------|---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
 | log_format         | object  | False    |         |              | Custom log format using key-value pairs in JSON format. Values can reference [APISIX variables](../apisix-variable.md) or [NGINX variables](https://nginx.org/en/docs/http/ngx_http_core_module.html) by prefixing with `$`. This configuration is global and applies to all Routes and Services that use the `splunk-hec-logging` Plugin. |
 | log_format_extra         | object  | False    |         |              | Extra log fields **added on top of** the default log entry, keeping every default field instead of replacing them (unlike `log_format`). Same value syntax as `log_format`. Ignored when `log_format` is set. |
-| max_pending_entries | integer | False   |         | >= 1         | Maximum number of unprocessed entries allowed in the batch processor. When this limit is reached, new entries will be dropped until the backlog is reduced.                                                                                                                      |
+| max_pending_entries | integer | False | 8192 | >= 1 | Maximum number of entries waiting to be processed. New entries are discarded while the backlog exceeds this, which stops a slow or unreachable log server from growing the worker's memory without bound. See [Batch Processor](../batch-processor.md#limiting-the-backlog) for the memory a backlog of this size costs. |
 
 ## Examples
 
diff --git a/docs/en/latest/plugins/syslog.md b/docs/en/latest/plugins/syslog.md
index 787c695d1304..b7e76a70309c 100644
--- a/docs/en/latest/plugins/syslog.md
+++ b/docs/en/latest/plugins/syslog.md
@@ -71,10 +71,11 @@ This Plugin supports using batch processors to aggregate and process entries (lo
 
 You can also set the format of the logs by configuring the Plugin metadata. The following configurations are available:
 
-| Name       | Type   | Required | Description                                                                                                                                                              |
-|------------|--------|----------|--------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
-| log_format | object | False    | Custom log format using key-value pairs in JSON format. Values can reference [NGINX variables](https://nginx.org/en/docs/http/ngx_http_core_module.html).                |
-| log_format_extra | object | False    | Extra log fields **added on top of** the default log entry, keeping every default field instead of replacing them (unlike `log_format`). Same value syntax as `log_format`. Ignored when `log_format` is set. |
+| Name       | Type   | Required | Default | Description                                                                                                                                                              |
+|------------|--------|----------|---------|--------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
+| log_format | object | False    |         | Custom log format using key-value pairs in JSON format. Values can reference [NGINX variables](https://nginx.org/en/docs/http/ngx_http_core_module.html).                |
+| log_format_extra | object | False    |         | Extra log fields **added on top of** the default log entry, keeping every default field instead of replacing them (unlike `log_format`). Same value syntax as `log_format`. Ignored when `log_format` is set. |
+| max_pending_entries | integer | False | 8192 | Maximum number of entries waiting to be processed. New entries are discarded while the backlog exceeds this, which stops a slow or unreachable log server from growing the worker's memory without bound. See [Batch Processor](../batch-processor.md#limiting-the-backlog) for the memory a backlog of this size costs. |
 
 :::info IMPORTANT
 
diff --git a/docs/en/latest/plugins/tcp-logger.md b/docs/en/latest/plugins/tcp-logger.md
index ac284d4143e5..cb29b3ac3f9e 100644
--- a/docs/en/latest/plugins/tcp-logger.md
+++ b/docs/en/latest/plugins/tcp-logger.md
@@ -104,8 +104,7 @@ You can also set the format of the logs by configuring the Plugin metadata. The
 | ---------- | ------ | -------- | ----------------------------------------------------------------------------- | ------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- |
 | log_format | object | False    |  | Log format declared as key-value pairs in JSON. Values support strings and nested objects (up to five levels deep; deeper fields are truncated). Within strings, [APISIX](../apisix-variable.md) or [NGINX](http://nginx.org/en/docs/varindex.html) variables can be referenced by prefixing with `$`. |
 | log_format_extra | object | False    |  | Extra log fields **added on top of** the default log entry, keeping every default field instead of replacing them (unlike `log_format`). Same value syntax as `log_format`. Ignored when `log_format` is set. |
-| max_pending_entries | integer | False | | Maximum number of pending entries that can be buffered in batch processor before it starts dropping them. |
-
+| max_pending_entries | integer | False | 8192 | Maximum number of entries waiting to be processed. New entries are discarded while the backlog exceeds this, which stops a slow or unreachable log server from growing the worker's memory without bound. See [Batch Processor](../batch-processor.md#limiting-the-backlog) for the memory a backlog of this size costs. |
 :::info IMPORTANT
 
 Configuring the Plugin metadata is global in scope. This means that it will take effect on all Routes and Services which use the `tcp-logger` Plugin.
diff --git a/docs/en/latest/plugins/tencent-cloud-cls.md b/docs/en/latest/plugins/tencent-cloud-cls.md
index 980072d3a3d9..6b02a4cf7cc6 100644
--- a/docs/en/latest/plugins/tencent-cloud-cls.md
+++ b/docs/en/latest/plugins/tencent-cloud-cls.md
@@ -104,8 +104,7 @@ You can also set the format of the logs by configuring the Plugin metadata. The
 | ---------- | ------ | -------- | ----------------------------------------------------------------------------- | ------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- |
 | log_format | object | False    |   | Log format declared as key-value pairs in JSON. Values support strings and nested objects (up to five levels deep; deeper fields are truncated). Within strings, [APISIX](../apisix-variable.md) or [NGINX](http://nginx.org/en/docs/varindex.html) variables can be referenced by prefixing with `$`. |
 | log_format_extra | object | False    |   | Extra log fields **added on top of** the default log entry, keeping every default field instead of replacing them (unlike `log_format`). Same value syntax as `log_format`. Ignored when `log_format` is set. |
-| max_pending_entries | integer | False | | Maximum number of pending entries that can be buffered in batch processor before it starts dropping them. |
-
+| max_pending_entries | integer | False | 8192 | Maximum number of entries waiting to be processed. New entries are discarded while the backlog exceeds this, which stops a slow or unreachable log server from growing the worker's memory without bound. See [Batch Processor](../batch-processor.md#limiting-the-backlog) for the memory a backlog of this size costs. |
 :::info IMPORTANT
 
 Configuring the Plugin metadata is global in scope. This means that it will take effect on all Routes and Services which use the `tencent-cloud-cls` Plugin.
diff --git a/docs/en/latest/plugins/udp-logger.md b/docs/en/latest/plugins/udp-logger.md
index 9eca52e934ee..02c2b3c37fa2 100644
--- a/docs/en/latest/plugins/udp-logger.md
+++ b/docs/en/latest/plugins/udp-logger.md
@@ -102,8 +102,7 @@ You can also set the format of the logs by configuring the Plugin metadata. The
 | ---------- | ------ | -------- | ----------------------------------------------------------------------------- | ------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- |
 | log_format | object | False    |  | Log format declared as key-value pairs in JSON. Values support strings and nested objects (up to five levels deep; deeper fields are truncated). Within strings, [APISIX](../apisix-variable.md) or [NGINX](http://nginx.org/en/docs/varindex.html) variables can be referenced by prefixing with `$`. |
 | log_format_extra | object | False    |  | Extra log fields **added on top of** the default log entry, keeping every default field instead of replacing them (unlike `log_format`). Same value syntax as `log_format`. Ignored when `log_format` is set. |
-| max_pending_entries | integer | False | | Maximum number of pending entries that can be buffered in batch processor before it starts dropping them. |
-
+| max_pending_entries | integer | False | 8192 | Maximum number of entries waiting to be processed. New entries are discarded while the backlog exceeds this, which stops a slow or unreachable log server from growing the worker's memory without bound. See [Batch Processor](../batch-processor.md#limiting-the-backlog) for the memory a backlog of this size costs. |
 :::info IMPORTANT
 
 Configuring the Plugin metadata is global in scope. This means that it will take effect on all Routes and Services which use the `udp-logger` Plugin.
diff --git a/docs/zh/latest/batch-processor.md b/docs/zh/latest/batch-processor.md
index b8f0290ffcfe..43a96fad6691 100644
--- a/docs/zh/latest/batch-processor.md
+++ b/docs/zh/latest/batch-processor.md
@@ -36,6 +36,30 @@ title: 批处理器
 | buffer_duration  | integer | 可选   | 60     | [1,...] | 必须先处理批次中最旧条目的最长期限（以秒为单位）。           |
 | max_retry_count  | integer | 可选   | 0      | [0,...] | 从处理管道中移除之前的最大重试次数。                         |
 | retry_delay      | integer | 可选   | 1      | [0,...] | 如果执行失败，则应延迟执行流程的秒数。                       |
+
+## 限制积压条目数
+
+已缓冲但尚未发送成功的条目保存在 worker 内存中。当日志服务变慢或不可达时，条目进入的速度快于离开的速度，积压量以及 worker 内存会随请求速率不断增长。
+
+因此所有基于批处理器的日志插件都通过[插件元数据](./terminology/plugin-metadata.md)提供 `max_pending_entries` 上限，默认值为 `8192`。积压超过该上限期间新条目会被丢弃，并且每秒最多向错误日志输出一条汇总信息：
+
+```text
+max pending entries limit exceeded. discarding entry. total_pushed_entries: 12289 total_processed_entries: 4096 max_pending_entries: 8192 discarded_entries: 3172
+```
+
+该上限限制的是条目数量，因此实际占用多少内存取决于单条条目有多大——尤其取决于是否开启 `include_req_body` 和 `include_resp_body`，以及 body 的大小。下表是日志服务接受连接但始终不响应时 worker 常驻内存的峰值增长，测试使用 `http-logger`、同时收集请求和响应 body，批处理器其余配置保持默认：
+
+| 每请求收集的 body | 默认上限下 worker 内存峰值 |
+|-------------------|----------------------------|
+| 不收集 body | ~40 MB |
+| 1 KB 请求 + 1 KB 响应 | ~100 MB |
+| 4 KB 请求 + 4 KB 响应 | ~250 MB |
+| 16 KB 请求 + 16 KB 响应 | ~840 MB |
+
+内存开销与 body 大小大致成正比，因此如果收集的 body 超过几 KB，应调低 `max_pending_entries`。表中数值高于条目本身的体积，是因为已经交给发送方的批次同时持有条目和由其序列化出的载荷。
+
+只有在发送跟不上时该上限才会起作用。日志服务正常的情况下，积压量接近 `batch_max_size`——在相同环境下 3000 QPS 时不足 1000 条，因此默认值为正常运行留出了约 8 倍余量。调大 `batch_max_size` 会同步抬高正常状态下的积压量，此时也应相应调大 `max_pending_entries`。
+
 以下代码显示了如何在你的插件中使用批处理器：
 
 ```lua
@@ -43,12 +67,17 @@ local bp_manager_mod = require("apisix.utils.batch-processor-manager")
 ...
 
 local plugin_name = "xxx-logger"
-local batch_processor_manager = bp_manager_mod.new(plugin_name)
+-- 第二个参数指定 max_pending_entries 所在的插件元数据名称，
+-- 仅当批处理器自身的名称与插件名不同时才需要传入
+local batch_processor_manager = bp_manager_mod.new("xxx logger", plugin_name)
 local schema = {...}
+local metadata_schema = {...}
 local _M = {
     ...
     name = plugin_name,
     schema = batch_processor_manager:wrap_schema(schema),
+    -- 向插件的元数据 schema 中加入 max_pending_entries
+    metadata_schema = batch_processor_manager:wrap_metadata_schema(metadata_schema),
 }
 
 ...
diff --git a/docs/zh/latest/plugins/clickhouse-logger.md b/docs/zh/latest/plugins/clickhouse-logger.md
index 2dbc8628de0d..0806519e5859 100644
--- a/docs/zh/latest/plugins/clickhouse-logger.md
+++ b/docs/zh/latest/plugins/clickhouse-logger.md
@@ -71,7 +71,7 @@ description: clickhouse-logger 插件将请求和响应日志批量推送到 Cli
 | 名称               | 类型    | 必选项 | 默认值 | 有效值 | 描述                                                                                                                                                                                                 |
 |--------------------|---------|--------|--------|--------|------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
 | log_format         | object  | False  |        |        | 以 JSON 键值对形式声明的自定义日志格式。值可通过 `$` 前缀引用 [APISIX 变量](../apisix-variable.md) 或 [NGINX 变量](https://nginx.org/en/docs/http/ngx_http_core_module.html)。该配置全局生效，对所有绑定 `clickhouse-logger` 的路由和服务生效。 |
-| max_pending_entries | integer | False |        | >= 1   | 批处理器中允许的最大未处理条目数。达到此限制后，新条目将被丢弃，直到积压减少。                                                                                                                         |
+| max_pending_entries | integer | False  | 8192 | >= 1 | 待处理条目数的上限。积压超过该值后新条目会被丢弃，避免日志服务变慢或不可达时 worker 内存无限增长。该上限对应的内存开销参见 [批处理器](../batch-processor.md#限制积压条目数)。 |
 
 ## 示例
 
diff --git a/docs/zh/latest/plugins/datadog.md b/docs/zh/latest/plugins/datadog.md
index 37d21dfd8030..516d6cd2c2ae 100644
--- a/docs/zh/latest/plugins/datadog.md
+++ b/docs/zh/latest/plugins/datadog.md
@@ -63,6 +63,7 @@ description: datadog 插件与 Datadog 集成，将指标批量发送到 DogStat
 | port          | integer | 否     | 8125                | DogStatsD 服务器端口。                                                                                                                 |
 | namespace     | string  | 否     | "apisix"            | APISIX agent 发送的所有自定义指标的前缀。有助于在指标图中定位实体，例如 `apisix.request.counter`。                                    |
 | constant_tags | array   | 否     | [ "source:apisix" ] | 嵌入到生成指标中的静态标签，便于按信号对指标进行分组。详见[标签定义](https://docs.datadoghq.com/getting_started/tagging/#defining-tags)。 |
+| max_pending_entries | integer | 否 | 8192 | 待处理条目数的上限。积压超过该值后新条目会被丢弃，避免日志服务变慢或不可达时 worker 内存无限增长。该上限对应的内存开销参见 [批处理器](../batch-processor.md#限制积压条目数)。 |
 
 ## 指标
 
diff --git a/docs/zh/latest/plugins/elasticsearch-logger.md b/docs/zh/latest/plugins/elasticsearch-logger.md
index e7912512bfc0..45ba4d2c1215 100644
--- a/docs/zh/latest/plugins/elasticsearch-logger.md
+++ b/docs/zh/latest/plugins/elasticsearch-logger.md
@@ -66,7 +66,7 @@ description: elasticsearch-logger Plugin 将请求和响应日志批量推送到
 | 名称 | 类型 | 必选项 | 默认值 | 描述 |
 |------|------|--------|--------|------|
 | log_format | object | 否 |  | 自定义日志格式以 JSON 的键值对声明。值支持字符串和嵌套对象（最多五层，超出部分将被截断）。字符串中可通过 `$` 前缀引用 [APISIX 变量](../apisix-variable.md) 和 [NGINX 变量](http://nginx.org/en/docs/varindex.html)。 |
-| max_pending_entries | integer | 否 | | 在批处理器开始丢弃条目之前，可缓冲在批处理器中的最大待处理条目数。 |
+| max_pending_entries | integer | 否 | 8192 | 待处理条目数的上限。积压超过该值后新条目会被丢弃，避免日志服务变慢或不可达时 worker 内存无限增长。该上限对应的内存开销参见 [批处理器](../batch-processor.md#限制积压条目数)。 |
 
 ## 示例
 
diff --git a/docs/zh/latest/plugins/google-cloud-logging.md b/docs/zh/latest/plugins/google-cloud-logging.md
index 41af9f8c5fd2..2b67eb72a787 100644
--- a/docs/zh/latest/plugins/google-cloud-logging.md
+++ b/docs/zh/latest/plugins/google-cloud-logging.md
@@ -66,7 +66,7 @@ description: google-cloud-logging 插件将请求和响应日志批量推送到
 | 名称               | 类型    | 必选项 | 默认值 | 有效值 | 描述                                                                                                                                                                                                 |
 |--------------------|---------|--------|--------|--------|------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
 | log_format         | object  | False  |        |        | 以 JSON 键值对形式声明的自定义日志格式。值可通过 `$` 前缀引用 [APISIX 变量](../apisix-variable.md) 或 [NGINX 变量](https://nginx.org/en/docs/http/ngx_http_core_module.html)。该配置全局生效，对所有绑定 `google-cloud-logging` 的路由和服务生效。 |
-| max_pending_entries | integer | False |        | >= 1   | 批处理器中允许的最大未处理条目数。达到此限制后，新条目将被丢弃，直到积压减少。                                                                                                                         |
+| max_pending_entries | integer | False  | 8192 | >= 1 | 待处理条目数的上限。积压超过该值后新条目会被丢弃，避免日志服务变慢或不可达时 worker 内存无限增长。该上限对应的内存开销参见 [批处理器](../batch-processor.md#限制积压条目数)。 |
 
 ## 示例
 
diff --git a/docs/zh/latest/plugins/http-logger.md b/docs/zh/latest/plugins/http-logger.md
index a73caaa99133..81aefaae4c78 100644
--- a/docs/zh/latest/plugins/http-logger.md
+++ b/docs/zh/latest/plugins/http-logger.md
@@ -63,11 +63,10 @@ description: http-logger 插件将请求和响应日志以 JSON 对象批量推
 
 也可以通过配置插件元数据来设置日志格式，可用配置如下：
 
-| 名称                | 类型    | 必选项 | 描述                                                                                                                                               |
-|---------------------|---------|--------|----------------------------------------------------------------------------------------------------------------------------------------------------|
-| log_format          | object  | False  | 以 JSON 键值对形式声明的自定义日志格式，值可以引用 [NGINX 变量](https://nginx.org/en/docs/http/ngx_http_core_module.html)。                         |
-| max_pending_entries | integer | False  | 批处理器中允许的最大未处理条目数。达到此限制后，新条目将被丢弃，直到积压减少。在 APISIX 3.15.0 版本中可用。                                         |
-
+| 名称                | 类型    | 必选项 | 默认值 | 描述                                                                                                                                               |
+|---------------------|---------|--------|---------|----------------------------------------------------------------------------------------------------------------------------------------------------|
+| log_format          | object  | False  |         | 以 JSON 键值对形式声明的自定义日志格式，值可以引用 [NGINX 变量](https://nginx.org/en/docs/http/ngx_http_core_module.html)。                         |
+| max_pending_entries | integer | False  | 8192 | 待处理条目数的上限。积压超过该值后新条目会被丢弃，避免日志服务变慢或不可达时 worker 内存无限增长。该上限对应的内存开销参见 [批处理器](../batch-processor.md#限制积压条目数)。 |
 :::info IMPORTANT
 
 插件元数据的配置为全局范围生效，将作用于所有使用 `http-logger` 插件的路由和服务。
diff --git a/docs/zh/latest/plugins/kafka-logger.md b/docs/zh/latest/plugins/kafka-logger.md
index b67fa3710d77..61fd64b85960 100644
--- a/docs/zh/latest/plugins/kafka-logger.md
+++ b/docs/zh/latest/plugins/kafka-logger.md
@@ -144,8 +144,7 @@ description: kafka-logger 插件将请求和响应日志作为 JSON 对象批量
 | 名称                | 类型    | 是否必需 | 默认值 | 描述                                                                                                                                                                                                                                    |
 | ------------------- | ------- | -------- | ------ | --------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- |
 | log_format          | object  | 否       |        | 以 JSON 键值对声明的日志格式。值支持字符串和嵌套对象（最多五层，超出部分将被截断）。字符串中可通过在前面加上 `$` 来引用 [APISIX 变量](../apisix-variable.md) 或 [NGINX 内置变量](http://nginx.org/en/docs/varindex.html)。               |
-| max_pending_entries | integer | 否       |        | 批处理器开始丢弃待处理条目之前可缓冲的最大待处理条目数。                                                                                                                                                                                |
-
+| max_pending_entries | integer | 否 | 8192 | 待处理条目数的上限。积压超过该值后新条目会被丢弃，避免日志服务变慢或不可达时 worker 内存无限增长。该上限对应的内存开销参见 [批处理器](../batch-processor.md#限制积压条目数)。 |
 :::info 重要
 
 插件元数据配置为全局生效。这意味着它将对所有使用 `kafka-logger` 插件的路由和服务生效。
diff --git a/docs/zh/latest/plugins/loggly.md b/docs/zh/latest/plugins/loggly.md
index 09e599f7748d..9b7feaea4f1f 100644
--- a/docs/zh/latest/plugins/loggly.md
+++ b/docs/zh/latest/plugins/loggly.md
@@ -68,6 +68,7 @@ description: API 网关 Apache APISIX loggly 插件可用于将日志转发到 S
 | timeout    | integer | 否    | 5000                 |                                | 发送数据请求超时时间（以毫秒为单位）。                                 |
 | protocol   | string  | 否    | "syslog"             | [ "syslog", "http", "https" ]  | 将日志发送到 Loggly 的协议。                                          |
 | log_format | object  | 否    | nil                  |                                | 日志格式以 JSON 的键值对声明。值支持字符串和嵌套对象（最多五层，超出部分将被截断）。字符串中可通过在前面加上 `$` 来引用 [APISIX 变量](../../../en/latest/apisix-variable.md) 或 [NGINX 内置变量](http://nginx.org/en/docs/varindex.html)。 |
+| max_pending_entries | integer | 否 | 8192 | >= 1 | 待处理条目数的上限。积压超过该值后新条目会被丢弃，避免日志服务变慢或不可达时 worker 内存无限增长。该上限对应的内存开销参见 [批处理器](../batch-processor.md#限制积压条目数)。 |
 
 APISIX 支持 [Syslog](https://documentation.solarwinds.com/en/success_center/loggly/content/admin/streaming-syslog-without-using-files.htm)、[HTTP/S](https://documentation.solarwinds.com/en/success_center/loggly/content/admin/http-bulk-endpoint.htm)（批量端点）协议将日志事件发送到 Loggly。**默认情况下 `protocol` 的值为 `syslog`**。该协议允许你通过一些细粒度的控制（基于上游 HTTP 响应代码的日志严重性映射）发送符合 RFC5424 的系统日志事件。但是 HTTP/S 批量端点非常适合以更快的传输速度发送更大量的日志事件。
 
diff --git a/docs/zh/latest/plugins/loki-logger.md b/docs/zh/latest/plugins/loki-logger.md
index a0ff70592f0f..e90657e62c31 100644
--- a/docs/zh/latest/plugins/loki-logger.md
+++ b/docs/zh/latest/plugins/loki-logger.md
@@ -70,7 +70,7 @@ description: loki-logger 插件通过 Loki HTTP API /loki/api/v1/push 将请求
 | 名称 | 类型 | 必选项 | 默认值 | 有效值 | 描述 |
 |------|------|--------|--------|--------|------|
 | log_format | object | 否 |  |  | 日志格式以 JSON 的键值对声明。值支持字符串和嵌套对象（最多五层，超出部分将被截断）。字符串中可通过在前面加上 `$` 来引用 [APISIX 变量](../apisix-variable.md) 和 [NGINX 变量](http://nginx.org/en/docs/varindex.html)。 |
-| max_pending_entries | integer | 否 | |  | 在批处理器开始丢弃条目之前，可缓冲在批处理器中的最大待处理条目数。 |
+| max_pending_entries | integer | 否 | 8192 | >= 1 | 待处理条目数的上限。积压超过该值后新条目会被丢弃，避免日志服务变慢或不可达时 worker 内存无限增长。该上限对应的内存开销参见 [批处理器](../batch-processor.md#限制积压条目数)。 |
 
 ## 示例
 
diff --git a/docs/zh/latest/plugins/rocketmq-logger.md b/docs/zh/latest/plugins/rocketmq-logger.md
index fe48e50fd9a1..0149a5640527 100644
--- a/docs/zh/latest/plugins/rocketmq-logger.md
+++ b/docs/zh/latest/plugins/rocketmq-logger.md
@@ -68,11 +68,10 @@ description: rocketmq-logger 插件将请求和响应日志以 JSON 对象批量
 
 也可以通过配置插件元数据来设置日志格式，可用配置如下：
 
-| 名称                | 类型    | 必选项 | 描述                                                                                                                                               |
-|---------------------|---------|--------|----------------------------------------------------------------------------------------------------------------------------------------------------|
-| log_format          | object  | False  | 以 JSON 键值对形式声明的自定义日志格式，值可以引用 [NGINX 变量](https://nginx.org/en/docs/http/ngx_http_core_module.html)。                         |
-| max_pending_entries | integer | False  | 批处理器中允许的最大未处理条目数。达到此限制后，新条目将被丢弃，直到积压减少。在 APISIX 3.15.0 版本中可用。                                         |
-
+| 名称                | 类型    | 必选项 | 默认值 | 描述                                                                                                                                               |
+|---------------------|---------|--------|---------|----------------------------------------------------------------------------------------------------------------------------------------------------|
+| log_format          | object  | False  |         | 以 JSON 键值对形式声明的自定义日志格式，值可以引用 [NGINX 变量](https://nginx.org/en/docs/http/ngx_http_core_module.html)。                         |
+| max_pending_entries | integer | False  | 8192 | 待处理条目数的上限。积压超过该值后新条目会被丢弃，避免日志服务变慢或不可达时 worker 内存无限增长。该上限对应的内存开销参见 [批处理器](../batch-processor.md#限制积压条目数)。 |
 :::info IMPORTANT
 
 插件元数据的配置为全局范围生效，将作用于所有使用 `rocketmq-logger` 插件的路由和服务。
diff --git a/docs/zh/latest/plugins/skywalking-logger.md b/docs/zh/latest/plugins/skywalking-logger.md
index 1d61cb4b876e..24bf2609fe27 100644
--- a/docs/zh/latest/plugins/skywalking-logger.md
+++ b/docs/zh/latest/plugins/skywalking-logger.md
@@ -63,7 +63,7 @@ description: skywalking-logger 将请求和响应日志作为 JSON 对象批量
 | 名称                    | 类型    | 必选项 | 默认值                | 有效值        | 描述                                                               |
 | ---------------------- | ------- | ------ | -------------------- | ------------- | ---------------------------------------------------------------- |
 | log_format | object | 否    |  | 日志格式以 JSON 的键值对声明。值支持字符串和嵌套对象（最多五层，超出部分将被截断）。字符串中可通过在前面加上 `$` 来引用 [APISIX 变量](../apisix-variable.md) 或 [NGINX 内置变量](http://nginx.org/en/docs/varindex.html)。 |
-| max_pending_entries | integer | 否 | | | 在批处理器中开始删除待处理条目之前可以购买的最大待处理条目数。|
+| max_pending_entries | integer | 否 | 8192 | >= 1 | 待处理条目数的上限。积压超过该值后新条目会被丢弃，避免日志服务变慢或不可达时 worker 内存无限增长。该上限对应的内存开销参见 [批处理器](../batch-processor.md#限制积压条目数)。 |
 
 ## 示例
 
diff --git a/docs/zh/latest/plugins/sls-logger.md b/docs/zh/latest/plugins/sls-logger.md
index f434a8b97d07..1ab15264f86a 100644
--- a/docs/zh/latest/plugins/sls-logger.md
+++ b/docs/zh/latest/plugins/sls-logger.md
@@ -85,6 +85,7 @@ title: sls-logger
 | 名称             | 类型    | 必选项 | 默认值        | 有效值  | 描述                                             |
 | ---------------- | ------- | ------ | ------------- | ------- | ------------------------------------------------ |
 | log_format       | object  | 可选   |  |         | 日志格式以 JSON 的键值对声明。值支持字符串和嵌套对象（最多五层，超出部分将被截断）。字符串中可通过在前面加上 `$` 来引用 [APISIX 变量](../../../en/latest/apisix-variable.md) 或 [Nginx 内置变量](http://nginx.org/en/docs/varindex.html)。特别的，**该设置是全局生效的**，意味着指定 log_format 后，将对所有绑定 sls-logger 的 Route 或 Service 生效。 |
+| max_pending_entries | integer | 可选 | 8192 | >= 1 | 待处理条目数的上限。积压超过该值后新条目会被丢弃，避免日志服务变慢或不可达时 worker 内存无限增长。该上限对应的内存开销参见 [批处理器](../batch-processor.md#限制积压条目数)。 |
 
 ### 设置日志格式示例
 
diff --git a/docs/zh/latest/plugins/splunk-hec-logging.md b/docs/zh/latest/plugins/splunk-hec-logging.md
index 3d948803ee11..a68cca99ef9c 100644
--- a/docs/zh/latest/plugins/splunk-hec-logging.md
+++ b/docs/zh/latest/plugins/splunk-hec-logging.md
@@ -62,7 +62,7 @@ description: splunk-hec-logging 插件将请求和响应上下文信息序列化
 | 名称               | 类型    | 必选项 | 默认值 | 有效值 | 描述                                                                                                                                                                                                 |
 |--------------------|---------|--------|--------|--------|------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
 | log_format         | object  | False  |        |        | 以 JSON 键值对形式声明的自定义日志格式。值可通过 `$` 前缀引用 [APISIX 变量](../apisix-variable.md) 或 [NGINX 变量](https://nginx.org/en/docs/http/ngx_http_core_module.html)。该配置全局生效，对所有绑定 `splunk-hec-logging` 的路由和服务生效。 |
-| max_pending_entries | integer | False |        | >= 1   | 批处理器中允许的最大未处理条目数。达到此限制后，新条目将被丢弃，直到积压减少。                                                                                                                         |
+| max_pending_entries | integer | False  | 8192 | >= 1 | 待处理条目数的上限。积压超过该值后新条目会被丢弃，避免日志服务变慢或不可达时 worker 内存无限增长。该上限对应的内存开销参见 [批处理器](../batch-processor.md#限制积压条目数)。 |
 
 ## 示例
 
diff --git a/docs/zh/latest/plugins/syslog.md b/docs/zh/latest/plugins/syslog.md
index d550517d98ef..eb3eb03f0dbf 100644
--- a/docs/zh/latest/plugins/syslog.md
+++ b/docs/zh/latest/plugins/syslog.md
@@ -71,9 +71,10 @@ description: syslog 插件将请求和响应日志以 JSON 对象批量推送到
 
 也可以通过配置插件元数据来设置日志格式，可用配置如下：
 
-| 名称       | 类型   | 必选项 | 描述                                                                                                                                               |
-|------------|--------|--------|----------------------------------------------------------------------------------------------------------------------------------------------------|
-| log_format | object | False  | 以 JSON 键值对形式声明的自定义日志格式，值可以引用 [NGINX 变量](https://nginx.org/en/docs/http/ngx_http_core_module.html)。                         |
+| 名称       | 类型   | 必选项 | 默认值 | 描述                                                                                                                                               |
+|------------|--------|--------|---------|----------------------------------------------------------------------------------------------------------------------------------------------------|
+| log_format | object | False  |         | 以 JSON 键值对形式声明的自定义日志格式，值可以引用 [NGINX 变量](https://nginx.org/en/docs/http/ngx_http_core_module.html)。                         |
+| max_pending_entries | integer | False | 8192 | 待处理条目数的上限。积压超过该值后新条目会被丢弃，避免日志服务变慢或不可达时 worker 内存无限增长。该上限对应的内存开销参见 [批处理器](../batch-processor.md#限制积压条目数)。 |
 
 :::info IMPORTANT
 
diff --git a/docs/zh/latest/plugins/tcp-logger.md b/docs/zh/latest/plugins/tcp-logger.md
index 097e55bc20b0..9669c7a1944f 100644
--- a/docs/zh/latest/plugins/tcp-logger.md
+++ b/docs/zh/latest/plugins/tcp-logger.md
@@ -95,8 +95,7 @@ description: 本文介绍了 API 网关 Apache APISIX 如何使用 tcp-logger 
 | 名称             | 类型    | 必选项 | 默认值        | 有效值  | 描述                                             |
 | ---------------- | ------- | ------ | ------------- | ------- | ------------------------------------------------ |
 | log_format       | object  | 否    |  |         | 日志格式以 JSON 的键值对声明。值支持字符串和嵌套对象（最多五层，超出部分将被截断）。字符串中可通过在前面加上 `$` 来引用 [APISIX 变量](../apisix-variable.md) 或 [NGINX 内置变量](http://nginx.org/en/docs/varindex.html)。 |
-| max_pending_entries | integer | 否 | | | 在批处理器中开始删除待处理条目之前可以购买的最大待处理条目数。|
-
+| max_pending_entries | integer | 否 | 8192 | >= 1 | 待处理条目数的上限。积压超过该值后新条目会被丢弃，避免日志服务变慢或不可达时 worker 内存无限增长。该上限对应的内存开销参见 [批处理器](../batch-processor.md#限制积压条目数)。 |
 :::info 注意
 
 该设置全局生效。如果指定了 `log_format`，则所有绑定 `tcp-logger` 的路由或服务都将使用该日志格式。
diff --git a/docs/zh/latest/plugins/tencent-cloud-cls.md b/docs/zh/latest/plugins/tencent-cloud-cls.md
index b35b764c760a..1c8486b4a788 100644
--- a/docs/zh/latest/plugins/tencent-cloud-cls.md
+++ b/docs/zh/latest/plugins/tencent-cloud-cls.md
@@ -98,8 +98,7 @@ description: API 网关 Apache APISIX tencent-cloud-cls 插件可用于将日志
 | 名称             | 类型    | 必选项 | 默认值        | 有效值  | 描述                                             |
 | ---------------- | ------- | ------ | ------------- | ------- | ------------------------------------------------ |
 | log_format       | object  | 否    |  |         | 日志格式以 JSON 的键值对声明。值支持字符串和嵌套对象（最多五层，超出部分将被截断）。字符串中可通过在前面加上 `$` 来引用 [APISIX 变量](../../../en/latest/apisix-variable.md) 或 [NGINX 内置变量](http://nginx.org/en/docs/varindex.html)。 |
-| max_pending_entries | integer | 否 | | | 在批处理器中开始删除待处理条目之前可以购买的最大待处理条目数。|
-
+| max_pending_entries | integer | 否 | 8192 | >= 1 | 待处理条目数的上限。积压超过该值后新条目会被丢弃，避免日志服务变慢或不可达时 worker 内存无限增长。该上限对应的内存开销参见 [批处理器](../batch-processor.md#限制积压条目数)。 |
 :::info 重要
 
 该设置全局生效。如果指定了 `log_format`，则所有绑定 `tencent-cloud-cls` 的路由或服务都将使用该日志格式。
diff --git a/docs/zh/latest/plugins/udp-logger.md b/docs/zh/latest/plugins/udp-logger.md
index 19017b909aab..3f4629f34029 100644
--- a/docs/zh/latest/plugins/udp-logger.md
+++ b/docs/zh/latest/plugins/udp-logger.md
@@ -94,8 +94,7 @@ description: 本文介绍了 API 网关 Apache APISIX 如何使用 udp-logger 
 | 名称             | 类型    | 必选项 | 默认值        | 有效值  | 描述                                             |
 | ---------------- | ------- | ------ | ------------- | ------- | ------------------------------------------------ |
 | log_format       | object  | 否    |  |         | 日志格式以 JSON 的键值对声明。值支持字符串和嵌套对象（最多五层，超出部分将被截断）。字符串中可通过在前面加上 `$` 来引用 [APISIX 变量](../apisix-variable.md) 或 [NGINX 内置变量](http://nginx.org/en/docs/varindex.html)。 |
-| max_pending_entries | integer | 否 | | | 在批处理器中开始删除待处理条目之前可以购买的最大待处理条目数。|
-
+| max_pending_entries | integer | 否 | 8192 | >= 1 | 待处理条目数的上限。积压超过该值后新条目会被丢弃，避免日志服务变慢或不可达时 worker 内存无限增长。该上限对应的内存开销参见 [批处理器](../batch-processor.md#限制积压条目数)。 |
 :::info 注意
 
 该设置全局生效。如果指定了 `log_format`，则所有绑定 `udp-logger` 的路由或服务都将使用该日志格式。
diff --git a/t/plugin/ai-proxy-kafka-log.t b/t/plugin/ai-proxy-kafka-log.t
index a6fddc052561..b21bd842028a 100644
--- a/t/plugin/ai-proxy-kafka-log.t
+++ b/t/plugin/ai-proxy-kafka-log.t
@@ -44,16 +44,16 @@ add_block_preprocessor(sub {
         core.log.info("send data to kafka: ", data)
     end
     local old_add = bp_manager.add_entry
-    bp_manager.add_entry = function(self, conf, entry, max_pending_entries)
-        local ok = old_add(self, conf, entry, max_pending_entries)
+    bp_manager.add_entry = function(self, conf, entry)
+        local ok = old_add(self, conf, entry)
         if ok then
             log_send_data(entry)
         end
         return ok
     end
     local old_new = bp_manager.add_entry_to_new_processor
-    bp_manager.add_entry_to_new_processor = function(self, conf, entry, ctx, func, max_pending_entries)
-        local ok = old_new(self, conf, entry, ctx, func, max_pending_entries)
+    bp_manager.add_entry_to_new_processor = function(self, conf, entry, ctx, func)
+        local ok = old_new(self, conf, entry, ctx, func)
         if ok then
             log_send_data(entry)
         end
diff --git a/t/plugin/kafka-logger-large-body.t b/t/plugin/kafka-logger-large-body.t
index 29c207e8ae6f..d566bb85624a 100644
--- a/t/plugin/kafka-logger-large-body.t
+++ b/t/plugin/kafka-logger-large-body.t
@@ -65,16 +65,16 @@ add_block_preprocessor(sub {
         core.log.info("send data to kafka: ", data)
     end
     local old_add = bp_manager.add_entry
-    bp_manager.add_entry = function(self, conf, entry, max_pending_entries)
-        local ok = old_add(self, conf, entry, max_pending_entries)
+    bp_manager.add_entry = function(self, conf, entry)
+        local ok = old_add(self, conf, entry)
         if ok then
             log_send_data(entry)
         end
         return ok
     end
     local old_new = bp_manager.add_entry_to_new_processor
-    bp_manager.add_entry_to_new_processor = function(self, conf, entry, ctx, func, max_pending_entries)
-        local ok = old_new(self, conf, entry, ctx, func, max_pending_entries)
+    bp_manager.add_entry_to_new_processor = function(self, conf, entry, ctx, func)
+        local ok = old_new(self, conf, entry, ctx, func)
         if ok then
             log_send_data(entry)
         end
diff --git a/t/plugin/kafka-logger-log-format.t b/t/plugin/kafka-logger-log-format.t
index a4ec304e57e4..db4c895529e2 100644
--- a/t/plugin/kafka-logger-log-format.t
+++ b/t/plugin/kafka-logger-log-format.t
@@ -34,16 +34,16 @@ add_block_preprocessor(sub {
         core.log.info("send data to kafka: ", data)
     end
     local old_add = bp_manager.add_entry
-    bp_manager.add_entry = function(self, conf, entry, max_pending_entries)
-        local ok = old_add(self, conf, entry, max_pending_entries)
+    bp_manager.add_entry = function(self, conf, entry)
+        local ok = old_add(self, conf, entry)
         if ok then
             log_send_data(entry)
         end
         return ok
     end
     local old_new = bp_manager.add_entry_to_new_processor
-    bp_manager.add_entry_to_new_processor = function(self, conf, entry, ctx, func, max_pending_entries)
-        local ok = old_new(self, conf, entry, ctx, func, max_pending_entries)
+    bp_manager.add_entry_to_new_processor = function(self, conf, entry, ctx, func)
+        local ok = old_new(self, conf, entry, ctx, func)
         if ok then
             log_send_data(entry)
         end
diff --git a/t/plugin/kafka-logger.t b/t/plugin/kafka-logger.t
index 6e355ba81657..61f17422e883 100644
--- a/t/plugin/kafka-logger.t
+++ b/t/plugin/kafka-logger.t
@@ -41,16 +41,16 @@ add_block_preprocessor(sub {
         core.log.info("send data to kafka: ", data)
     end
     local old_add = bp_manager.add_entry
-    bp_manager.add_entry = function(self, conf, entry, max_pending_entries)
-        local ok = old_add(self, conf, entry, max_pending_entries)
+    bp_manager.add_entry = function(self, conf, entry)
+        local ok = old_add(self, conf, entry)
         if ok then
             log_send_data(entry)
         end
         return ok
     end
     local old_new = bp_manager.add_entry_to_new_processor
-    bp_manager.add_entry_to_new_processor = function(self, conf, entry, ctx, func, max_pending_entries)
-        local ok = old_new(self, conf, entry, ctx, func, max_pending_entries)
+    bp_manager.add_entry_to_new_processor = function(self, conf, entry, ctx, func)
+        local ok = old_new(self, conf, entry, ctx, func)
         if ok then
             log_send_data(entry)
         end
diff --git a/t/plugin/kafka-logger2.t b/t/plugin/kafka-logger2.t
index 8ba42999b3d7..572d68218b93 100644
--- a/t/plugin/kafka-logger2.t
+++ b/t/plugin/kafka-logger2.t
@@ -41,16 +41,16 @@ add_block_preprocessor(sub {
         core.log.info("send data to kafka: ", data)
     end
     local old_add = bp_manager.add_entry
-    bp_manager.add_entry = function(self, conf, entry, max_pending_entries)
-        local ok = old_add(self, conf, entry, max_pending_entries)
+    bp_manager.add_entry = function(self, conf, entry)
+        local ok = old_add(self, conf, entry)
         if ok then
             log_send_data(entry)
         end
         return ok
     end
     local old_new = bp_manager.add_entry_to_new_processor
-    bp_manager.add_entry_to_new_processor = function(self, conf, entry, ctx, func, max_pending_entries)
-        local ok = old_new(self, conf, entry, ctx, func, max_pending_entries)
+    bp_manager.add_entry_to_new_processor = function(self, conf, entry, ctx, func)
+        local ok = old_new(self, conf, entry, ctx, func)
         if ok then
             log_send_data(entry)
         end
diff --git a/t/plugin/kafka-logger4.t b/t/plugin/kafka-logger4.t
index 95969705d586..176b5a5ec370 100644
--- a/t/plugin/kafka-logger4.t
+++ b/t/plugin/kafka-logger4.t
@@ -41,16 +41,16 @@ add_block_preprocessor(sub {
         core.log.info("send data to kafka: ", data)
     end
     local old_add = bp_manager.add_entry
-    bp_manager.add_entry = function(self, conf, entry, max_pending_entries)
-        local ok = old_add(self, conf, entry, max_pending_entries)
+    bp_manager.add_entry = function(self, conf, entry)
+        local ok = old_add(self, conf, entry)
         if ok then
             log_send_data(entry)
         end
         return ok
     end
     local old_new = bp_manager.add_entry_to_new_processor
-    bp_manager.add_entry_to_new_processor = function(self, conf, entry, ctx, func, max_pending_entries)
-        local ok = old_new(self, conf, entry, ctx, func, max_pending_entries)
+    bp_manager.add_entry_to_new_processor = function(self, conf, entry, ctx, func)
+        local ok = old_new(self, conf, entry, ctx, func)
         if ok then
             log_send_data(entry)
         end
diff --git a/t/plugin/rocketmq-logger-log-format.t b/t/plugin/rocketmq-logger-log-format.t
index fc9d0753e079..d8fda2b5a698 100644
--- a/t/plugin/rocketmq-logger-log-format.t
+++ b/t/plugin/rocketmq-logger-log-format.t
@@ -34,16 +34,16 @@ add_block_preprocessor(sub {
         core.log.info("send data to rocketmq: ", data)
     end
     local old_add = bp_manager.add_entry
-    bp_manager.add_entry = function(self, conf, entry, max_pending_entries)
-        local ok = old_add(self, conf, entry, max_pending_entries)
+    bp_manager.add_entry = function(self, conf, entry)
+        local ok = old_add(self, conf, entry)
         if ok then
             log_send_data(entry)
         end
         return ok
     end
     local old_new = bp_manager.add_entry_to_new_processor
-    bp_manager.add_entry_to_new_processor = function(self, conf, entry, ctx, func, max_pending_entries)
-        local ok = old_new(self, conf, entry, ctx, func, max_pending_entries)
+    bp_manager.add_entry_to_new_processor = function(self, conf, entry, ctx, func)
+        local ok = old_new(self, conf, entry, ctx, func)
         if ok then
             log_send_data(entry)
         end
diff --git a/t/plugin/rocketmq-logger.t b/t/plugin/rocketmq-logger.t
index cfa7ca669662..63c542196b1b 100644
--- a/t/plugin/rocketmq-logger.t
+++ b/t/plugin/rocketmq-logger.t
@@ -41,16 +41,16 @@ add_block_preprocessor(sub {
         core.log.info("send data to rocketmq: ", data)
     end
     local old_add = bp_manager.add_entry
-    bp_manager.add_entry = function(self, conf, entry, max_pending_entries)
-        local ok = old_add(self, conf, entry, max_pending_entries)
+    bp_manager.add_entry = function(self, conf, entry)
+        local ok = old_add(self, conf, entry)
         if ok then
             log_send_data(entry)
         end
         return ok
     end
     local old_new = bp_manager.add_entry_to_new_processor
-    bp_manager.add_entry_to_new_processor = function(self, conf, entry, ctx, func, max_pending_entries)
-        local ok = old_new(self, conf, entry, ctx, func, max_pending_entries)
+    bp_manager.add_entry_to_new_processor = function(self, conf, entry, ctx, func)
+        local ok = old_new(self, conf, entry, ctx, func)
         if ok then
             log_send_data(entry)
         end
diff --git a/t/plugin/rocketmq-logger2.t b/t/plugin/rocketmq-logger2.t
index 7da7a92367e6..80c9bf7f8d73 100644
--- a/t/plugin/rocketmq-logger2.t
+++ b/t/plugin/rocketmq-logger2.t
@@ -41,16 +41,16 @@ add_block_preprocessor(sub {
         core.log.info("send data to rocketmq: ", data)
     end
     local old_add = bp_manager.add_entry
-    bp_manager.add_entry = function(self, conf, entry, max_pending_entries)
-        local ok = old_add(self, conf, entry, max_pending_entries)
+    bp_manager.add_entry = function(self, conf, entry)
+        local ok = old_add(self, conf, entry)
         if ok then
             log_send_data(entry)
         end
         return ok
     end
     local old_new = bp_manager.add_entry_to_new_processor
-    bp_manager.add_entry_to_new_processor = function(self, conf, entry, ctx, func, max_pending_entries)
-        local ok = old_new(self, conf, entry, ctx, func, max_pending_entries)
+    bp_manager.add_entry_to_new_processor = function(self, conf, entry, ctx, func)
+        local ok = old_new(self, conf, entry, ctx, func)
         if ok then
             log_send_data(entry)
         end
diff --git a/t/plugin/sls-logger.t b/t/plugin/sls-logger.t
index f5d5d027a82f..6bc901e42571 100644
--- a/t/plugin/sls-logger.t
+++ b/t/plugin/sls-logger.t
@@ -31,9 +31,9 @@ add_block_preprocessor(sub {
     local bp_manager = require("apisix.utils.batch-processor-manager")
     local core = require("apisix.core")
     local old_f = bp_manager.add_entry_to_new_processor
-    bp_manager.add_entry_to_new_processor = function(self, conf, entry, ctx, func, max_pending_entries)
+    bp_manager.add_entry_to_new_processor = function(self, conf, entry, ctx, func)
         ngx.log(ngx.INFO, "batch_entry: ", entry.data or core.json.encode(entry))
-        return old_f(self, conf, entry, ctx, func, max_pending_entries)
+        return old_f(self, conf, entry, ctx, func)
     end
 _EOC_
 
diff --git a/t/plugin/syslog.t b/t/plugin/syslog.t
index 7ce5c1ed88e0..e8268fe8b85b 100644
--- a/t/plugin/syslog.t
+++ b/t/plugin/syslog.t
@@ -35,16 +35,16 @@ add_block_preprocessor(sub {
             core.log.info("collect_data:", data)
         end
         local _orig_add = bp_manager.add_entry
-        bp_manager.add_entry = function(self, conf, entry, max_pending_entries)
-            local ok = _orig_add(self, conf, entry, max_pending_entries)
+        bp_manager.add_entry = function(self, conf, entry)
+            local ok = _orig_add(self, conf, entry)
             if ok then
                 log_collect_data(entry)
             end
             return ok
         end
         local _orig_new = bp_manager.add_entry_to_new_processor
-        bp_manager.add_entry_to_new_processor = function(self, conf, entry, ctx, func, max_pending_entries)
-            local ok = _orig_new(self, conf, entry, ctx, func, max_pending_entries)
+        bp_manager.add_entry_to_new_processor = function(self, conf, entry, ctx, func)
+            local ok = _orig_new(self, conf, entry, ctx, func)
             if ok then
                 log_collect_data(entry)
             end
diff --git a/t/plugin/tcp-logger.t b/t/plugin/tcp-logger.t
index 76aca2112c1f..ef676ed3bb81 100644
--- a/t/plugin/tcp-logger.t
+++ b/t/plugin/tcp-logger.t
@@ -31,9 +31,9 @@ add_block_preprocessor(sub {
     local bp_manager = require("apisix.utils.batch-processor-manager")
     local core = require("apisix.core")
     local old_f = bp_manager.add_entry_to_new_processor
-    bp_manager.add_entry_to_new_processor = function(self, conf, entry, ctx, func, max_pending_entries)
+    bp_manager.add_entry_to_new_processor = function(self, conf, entry, ctx, func)
         ngx.log(ngx.INFO, "batch_entry: ", core.json.encode(entry))
-        return old_f(self, conf, entry, ctx, func, max_pending_entries)
+        return old_f(self, conf, entry, ctx, func)
     end
 _EOC_
 
diff --git a/t/plugin/udp-logger.t b/t/plugin/udp-logger.t
index da81fcb49c40..42531953dcba 100644
--- a/t/plugin/udp-logger.t
+++ b/t/plugin/udp-logger.t
@@ -31,9 +31,9 @@ add_block_preprocessor(sub {
     local bp_manager = require("apisix.utils.batch-processor-manager")
     local core = require("apisix.core")
     local old_f = bp_manager.add_entry_to_new_processor
-    bp_manager.add_entry_to_new_processor = function(self, conf, entry, ctx, func, max_pending_entries)
+    bp_manager.add_entry_to_new_processor = function(self, conf, entry, ctx, func)
         ngx.log(ngx.INFO, "batch_entry: ", core.json.encode(entry))
-        return old_f(self, conf, entry, ctx, func, max_pending_entries)
+        return old_f(self, conf, entry, ctx, func)
     end
 _EOC_
 
diff --git a/t/utils/batch-processor-manager.t b/t/utils/batch-processor-manager.t
new file mode 100644
index 000000000000..88bc3b166dd7
--- /dev/null
+++ b/t/utils/batch-processor-manager.t
@@ -0,0 +1,374 @@
+#
+# Licensed to the Apache Software Foundation (ASF) under one or more
+# contributor license agreements.  See the NOTICE file distributed with
+# this work for additional information regarding copyright ownership.
+# The ASF licenses this file to You under the Apache License, Version 2.0
+# (the "License"); you may not use this file except in compliance with
+# the License.  You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+#
+use t::APISIX 'no_plan';
+
+log_level('info');
+repeat_each(1);
+no_long_string();
+no_root_location();
+run_tests;
+
+__DATA__
+
+=== TEST 1: the backlog is capped even with no plugin metadata configured
+--- config
+    location /t {
+        content_by_lua_block {
+            local bp_manager_mod = require("apisix.utils.batch-processor-manager")
+            local bp_manager = bp_manager_mod.new("test logger", "test-logger")
+            -- a batch that is never flushed, so every accepted entry stays pending
+            local conf = {
+                name = "test logger",
+                batch_max_size = 10000000,
+                inactive_timeout = 300,
+                buffer_duration = 300,
+                max_retry_count = 0,
+                retry_delay = 1,
+            }
+            local ctx = {var = {route_id = "1", server_addr = "127.0.0.1"}}
+            local func = function() return true end
+
+            local accepted = 0
+            for i = 1, 20000 do
+                local ok = bp_manager:add_entry(conf, i)
+                if not ok then
+                    ok = bp_manager:add_entry_to_new_processor(conf, i, ctx, func)
+                end
+                if ok then
+                    accepted = accepted + 1
+                end
+            end
+            ngx.say("accepted: ", accepted)
+        }
+    }
+--- request
+GET /t
+--- response_body
+accepted: 8192
+--- error_log
+max pending entries limit exceeded. discarding entry
+
+
+
+=== TEST 2: max_pending_entries in the plugin's metadata overrides the default
+--- config
+    location /t {
+        content_by_lua_block {
+            local plugin = require("apisix.plugin")
+            plugin.plugin_metadatas = {
+                get = function(self, name)
+                    if name == "test-logger" then
+                        return {value = {max_pending_entries = 3}}
+                    end
+                end
+            }
+
+            local bp_manager_mod = require("apisix.utils.batch-processor-manager")
+            local bp_manager = bp_manager_mod.new("test logger", "test-logger")
+            local conf = {
+                name = "test logger",
+                batch_max_size = 10000000,
+                inactive_timeout = 300,
+                buffer_duration = 300,
+                max_retry_count = 0,
+                retry_delay = 1,
+            }
+            local ctx = {var = {route_id = "1", server_addr = "127.0.0.1"}}
+            local func = function() return true end
+
+            local accepted = 0
+            for i = 1, 10 do
+                local ok = bp_manager:add_entry(conf, i)
+                if not ok then
+                    ok = bp_manager:add_entry_to_new_processor(conf, i, ctx, func)
+                end
+                if ok then
+                    accepted = accepted + 1
+                end
+            end
+            ngx.say("accepted: ", accepted)
+        }
+    }
+--- request
+GET /t
+--- response_body
+accepted: 3
+--- error_log
+max_pending_entries: 3
+
+
+
+=== TEST 3: discarding is reported at most once per second, with a running count
+--- config
+    location /t {
+        content_by_lua_block {
+            local plugin = require("apisix.plugin")
+            plugin.plugin_metadatas = {
+                get = function(self, name)
+                    return {value = {max_pending_entries = 1}}
+                end
+            }
+
+            local bp_manager_mod = require("apisix.utils.batch-processor-manager")
+            local bp_manager = bp_manager_mod.new("test logger", "test-logger")
+            local conf = {
+                name = "test logger",
+                batch_max_size = 10000000,
+                inactive_timeout = 300,
+                buffer_duration = 300,
+                max_retry_count = 0,
+                retry_delay = 1,
+            }
+            local ctx = {var = {route_id = "1", server_addr = "127.0.0.1"}}
+            local func = function() return true end
+
+            local push = function(n)
+                for i = 1, n do
+                    local ok = bp_manager:add_entry(conf, i)
+                    if not ok then
+                        bp_manager:add_entry_to_new_processor(conf, i, ctx, func)
+                    end
+                end
+            end
+
+            -- one entry fits, the other 99 are discarded but reported only once
+            push(100)
+            -- past the interval the next discard reports, and its count covers
+            -- every entry discarded since the previous report
+            ngx.sleep(1.1)
+            push(5)
+            ngx.say("done")
+        }
+    }
+--- request
+GET /t
+--- response_body
+done
+--- grep_error_log eval
+qr/discarded_entries: \d+/
+--- grep_error_log_out
+discarded_entries: 1
+discarded_entries: 99
+
+
+
+=== TEST 4: every batch-processor based logger exposes max_pending_entries
+--- config
+    location /t {
+        content_by_lua_block {
+            local loggers = {
+                "clickhouse-logger", "datadog", "elasticsearch-logger",
+                "google-cloud-logging", "http-logger", "kafka-logger", "lago",
+                "loggly", "loki-logger", "rocketmq-logger", "skywalking-logger",
+                "sls-logger", "splunk-hec-logging", "syslog", "tcp-logger",
+                "tencent-cloud-cls", "udp-logger",
+            }
+            table.insert(loggers, "stream syslog")
+            for _, name in ipairs(loggers) do
+                local mod = require(name == "stream syslog"
+                                    and "apisix.stream.plugins.syslog"
+                                    or "apisix.plugins." .. name)
+                local schema = mod.metadata_schema
+                local prop = schema and schema.properties
+                             and schema.properties.max_pending_entries
+                if not prop or not prop.default then
+                    ngx.say(name, ": missing max_pending_entries default")
+                end
+            end
+            ngx.say("done")
+        }
+    }
+--- request
+GET /t
+--- response_body
+done
+
+
+
+=== TEST 5: every logger's batch processor reads its own plugin's metadata
+--- config
+    location /t {
+        content_by_lua_block {
+            -- a manager built without its plugin name looks metadata up under the
+            -- batch processor's display name, silently ignoring any override
+            local loggers = {
+                "clickhouse-logger", "datadog", "elasticsearch-logger",
+                "google-cloud-logging", "http-logger", "kafka-logger", "lago",
+                "loggly", "loki-logger", "rocketmq-logger", "skywalking-logger",
+                "sls-logger", "splunk-hec-logging", "syslog", "tcp-logger",
+                "tencent-cloud-cls", "udp-logger",
+            }
+            -- the stream plugin and the shared syslog module both log as "syslog"
+            local modules = {["apisix.stream.plugins.syslog"] = "syslog"}
+            local order = {}
+            for _, name in ipairs(loggers) do
+                modules["apisix.plugins." .. name] = name
+                table.insert(order, "apisix.plugins." .. name)
+            end
+            table.insert(order, "apisix.stream.plugins.syslog")
+
+            local bp_manager_mod = require("apisix.utils.batch-processor-manager")
+            local orig_new = bp_manager_mod.new
+            local created
+            local checked = 0
+
+            for _, path in ipairs(order) do
+                -- syslog keeps its batch processor in a module shared with the
+                -- stream plugin; reload it alongside so whichever plugin is under
+                -- test is the one that builds it
+                package.loaded["apisix.plugins.syslog.init"] = nil
+                package.loaded[path] = nil
+
+                created = {}
+                bp_manager_mod.new = function(name, plugin_name)
+                    local manager = orig_new(name, plugin_name)
+                    table.insert(created, manager)
+                    return manager
+                end
+                require(path)
+                bp_manager_mod.new = orig_new
+
+                if #created == 0 then
+                    ngx.say(path, " built no batch processor")
+                end
+                for _, manager in ipairs(created) do
+                    checked = checked + 1
+                    if manager.plugin_name ~= modules[path] then
+                        ngx.say(path, ": batch processor '", manager.name,
+                                "' reads the metadata of '", manager.plugin_name,
+                                "', expected '", modules[path], "'")
+                    end
+                end
+            end
+            ngx.say("checked ", checked, " batch processors")
+        }
+    }
+--- request
+GET /t
+--- response_body
+checked 20 batch processors
+
+
+
+=== TEST 6: max_pending_entries is validated through each plugin's metadata schema
+--- config
+    location /t {
+        content_by_lua_block {
+            local core = require("apisix.core")
+            local loggers = {
+                "clickhouse-logger", "datadog", "elasticsearch-logger",
+                "google-cloud-logging", "http-logger", "kafka-logger", "lago",
+                "loggly", "loki-logger", "rocketmq-logger", "skywalking-logger",
+                "sls-logger", "splunk-hec-logging", "syslog", "tcp-logger",
+                "tencent-cloud-cls", "udp-logger",
+            }
+            table.insert(loggers, "stream syslog")
+            for _, name in ipairs(loggers) do
+                local mod = require(name == "stream syslog"
+                                    and "apisix.stream.plugins.syslog"
+                                    or "apisix.plugins." .. name)
+                local ok, err = mod.check_schema({max_pending_entries = 100},
+                                                 core.schema.TYPE_METADATA)
+                if not ok then
+                    ngx.say(name, " rejected a valid override: ", err)
+                end
+                if mod.check_schema({max_pending_entries = 0},
+                                    core.schema.TYPE_METADATA) then
+                    ngx.say(name, " accepted max_pending_entries = 0")
+                end
+            end
+            ngx.say("done")
+        }
+    }
+--- request
+GET /t
+--- response_body
+done
+
+
+
+=== TEST 7: the limit reaches a plugin that never carried it before
+--- extra_yaml_config
+plugins:
+  - sls-logger
+--- config
+location /t {
+    content_by_lua_block {
+        local http = require "resty.http"
+        local httpc = http.new()
+        local t = require("lib.test_admin").test
+
+        local code, body = t('/apisix/admin/plugin_metadata/sls-logger',
+                             ngx.HTTP_PUT, {max_pending_entries = 1})
+        if code >= 300 then
+            ngx.status = code
+            ngx.say(body)
+            return
+        end
+
+        -- nothing listens on the log port, and retries keep the first entry
+        -- pending, so everything after it is over the limit
+        code, body = t('/apisix/admin/routes/1', ngx.HTTP_PUT, {
+            plugins = {
+                ["sls-logger"] = {
+                    host = "127.0.0.1",
+                    port = 1234,
+                    project = "test-project",
+                    logstore = "test-logstore",
+                    access_key_id = "test-key-id",
+                    access_key_secret = "test-key-secret",
+                    batch_max_size = 1,
+                    max_retry_count = 10,
+                    retry_delay = 1,
+                    timeout = 1,
+                },
+            },
+            upstream = {
+                nodes = {["127.0.0.1:1980"] = 1},
+                type = "roundrobin",
+            },
+            uri = "/hello",
+        })
+        if code >= 300 then
+            ngx.status = code
+            ngx.say(body)
+            return
+        end
+
+        local uri = "http://127.0.0.1:" .. ngx.var.server_port .. "/hello"
+        for i = 1, 3 do
+            local res, err = httpc:request_uri(uri, {method = "GET"})
+            if not res then
+                ngx.say("request ", i, " failed: ", err)
+                return
+            end
+            if res.status ~= 200 then
+                ngx.say("request ", i, " returned ", res.status)
+                return
+            end
+        end
+        ngx.sleep(1)
+        ngx.say("passed")
+    }
+}
+--- request
+GET /t
+--- response_body
+passed
+--- error_log
+max pending entries limit exceeded. discarding entry
+--- timeout: 5