Apache 2.4 adaptor: release the shared-memory mapping on restart (fixes ENOMEM after ~1 year of graceful restarts)

Utilities/Adaptors/Adaptor/shmem.c

@@ -274,6 +274,33 @@ int WOShmem_init(const char *file, size_t memsize)
    return WOShmem_fd == -1;
 }
 
+/*
+ * Release the mapping made by WOShmem_init() and close its file descriptor.
+ *
+ * Apache unloads and reloads this module on every graceful restart or restart
+ * (SIGUSR1 / SIGHUP), which resets the statics above and runs WOShmem_init()
+ * again in the SAME parent process: a fresh, already-unlinked state file was
+ * mapped each time and the previous mapping was never released. On a 32-bit
+ * server every restart therefore ate address space until mmap() failed with
+ * ENOMEM ("WOShmem_init(): couldn't map file: Not enough space") and the
+ * adaptor declined every request until Apache was fully stopped and started
+ * (seen 2026-09-27 on an AIX box after about a year of nightly logrotate
+ * restarts). The Apache module calls this from a cleanup registered on the
+ * configuration pool, which Apache clears before each restart.
+ * Safe to call when nothing is mapped. Children that still hold the old
+ * mapping are not affected: the file lives on until its last mapping goes.
+ */
+void WOShmem_cleanup(void)
+{
+   if (WOShmem_base_address != MAP_FAILED && WOShmem_size != 0 && WOShmem_size != (unsigned int)-1)
+      munmap(WOShmem_base_address, WOShmem_size);
+   WOShmem_base_address = MAP_FAILED;
+   WOShmem_size = 0;
+   if (WOShmem_fd != -1)
+      close(WOShmem_fd);
+   WOShmem_fd = -1;
+}
+
 
 
 void *WOShmem_alloc(const char *regionName, size_t elementSize, unsigned int *elementCount)

Utilities/Adaptors/Adaptor/shmem.h

@@ -56,6 +56,11 @@ and limitations under the License.
  */
 int WOShmem_init(const char *file, size_t memsize);
 
+/*
+ * Unmap the shared memory and close the backing file. See shmem.c.
+ */
+void WOShmem_cleanup(void);
+
 /*
  * Allocate or look up a chunk of shared memory.
  * regionName specifies the name of the region to locate.

Utilities/Adaptors/Apache2.4/mod_WebObjects.c

@@ -41,6 +41,7 @@
  */
 
 #include "config.h"
+#include "shmem.h"
 #include "womalloc.h"
 #include "request.h"
 #include "response.h"
@@ -617,10 +618,31 @@ static void *WebObjects_create_config(apr_pool_t *p, server_rec *s)
  *	to assume it's in the apache conf directory.
  *
  */
+/*
+ *	Runs when Apache clears the configuration pool: at every graceful restart or
+ *	restart, before the configuration is read again and this module is reloaded.
+ *	Releases the shared-memory mapping that init_adaptor() made (see
+ *	WOShmem_cleanup in shmem.c for why this matters).
+ */
+static apr_status_t WebObjects_shutdown(void *data) {
+    WOShmem_cleanup();
+    adaptorEnabled = 0;
+    initCalled = 0;
+    return APR_SUCCESS;
+}
+
 static int WebObjects_post_config(apr_pool_t *pconf, apr_pool_t *plog,
                                    apr_pool_t *ptemp, server_rec *s)  {
     WebObjects_config *wc;
 
+    /*
+     *	Apache runs post_config twice when it starts (the first pass only checks
+     *	the configuration) and once per restart. Nothing is mapped during the
+     *	check pass, which also covers "apachectl configtest".
+     */
+    if (ap_state_query(AP_SQ_MAIN_STATE) == AP_SQ_MS_CREATE_PRE_CONFIG)
+        return OK;
+
     if(!initCalled) {
         _webobjects_server = s;
         wc = (WebObjects_config *)ap_get_module_config(s->module_config, &WebObjects_module);
@@ -635,10 +657,12 @@ static int WebObjects_post_config(apr_pool_t *pconf, apr_pool_t *plog,
             adaptorEnabled = 1;
         } else {
             WOLog(WO_ERR, "WebObjects_post_config(): Adaptor initialization failed. All requests will be declined.");
+            WOShmem_cleanup();
             return DECLINED;
         }
 
         initCalled = 1;
+        apr_pool_cleanup_register(pconf, NULL, WebObjects_shutdown, apr_pool_cleanup_null);
     }
 
     return OK;