perf: minimize streamMu lock scope in sendRequestDefault - #10
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AppendRows on a managed writer's DefaultStream can block when the inflight queue (Max_Queue_Requests / Max_Queue_Bytes) is saturated. Holding streamMu for the entire duration serialized all concurrent flush calls on the same output instance, directly contributing to the 30s latency spikes observed under peak input load. Changes: - Add getStream(), appendResult(), leastLoadedStreamIndex() methods on outputConfig to encapsulate the lock/unlock boilerplate and narrow each critical section to slice access only. - Refactor sendRequestDefault to call AppendRows outside streamMu, using getStream() to fetch the stream pointer and appendResult() to enqueue the result after the call returns. - Refactor flushChunk to use leastLoadedStreamIndex() (no behavior change, removes the explicit Lock/Unlock pair). AppendRows on managedwriter.ManagedStream is goroutine-safe; the lock is no longer needed to protect the call itself. For the at-least-once (DefaultStream) path there is no stream rebuilding, so the *streamConfig pointer obtained under the lock remains valid after the lock is released.
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Summary
Previously,
sendRequestDefaultheldstreamMufor the entire durationof
AppendRows, blocking all concurrent flushes whenever the inflightqueue (Max_Queue_Requests / Max_Queue_Bytes) was saturated.
This PR narrows the critical section so that the lock is acquired only
for the slice access and result append, allowing
AppendRowsto executeconcurrently without holding the lock.
Changes
outputConfig:getStream(index)— acquiresstreamMuonly to read the stream pointerappendResult(stream, result)— acquiresstreamMuonly to append the resultleastLoadedStreamIndex()— acquiresstreamMuonly to find the least-loaded streamsendRequestDefaultandflushChunkwith these helpers