Fixing edge-case when ReadPartitionSession could stop reading - #706
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Myllyenko wants to merge 1 commit into
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Fixing edge-case when ReadPartitionSession could stop reading#706Myllyenko wants to merge 1 commit into
Myllyenko wants to merge 1 commit into
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sendDataToReadersIfNeeded takes the isReadingNow flag, peeks the queue and, when nothing is deliverable, releases the flag again. The existing re-check only covered the case of a batch that was already queued and became ready in the meantime; when the queue looked empty at peek() time the method returned without looking again. That leaves a lost wakeup. While the flag is held, the grpc thread can offer an already decoded (RAW) batch in addBatches and call sendDataToReadersIfNeeded, whose compareAndSet fails and is silently dropped. The batch is then never delivered, its read future never completes, the allOf in ReadSession.onReadResponse never fires and the session stops sending ReadRequests - the reader stalls forever. Re-read the head of the queue after releasing the flag instead of re-testing the batch captured before it, and turn the retry into a loop so a burst of these hand-offs cannot nest recursively.
Codecov Report✅ All modified and coverable lines are covered by tests. Additional details and impacted files@@ Coverage Diff @@
## master #706 +/- ##
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+ Coverage 71.91% 72.44% +0.53%
- Complexity 3474 3522 +48
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Files 390 391 +1
Lines 16220 16340 +120
Branches 1698 1701 +3
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+ Hits 11664 11837 +173
+ Misses 3904 3865 -39
+ Partials 652 638 -14 ☔ View full report in Codecov by Harness. 🚀 New features to boost your workflow:
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ReadPartitionSession.sendDataToReadersIfNeededtakes theisReadingNowflag, peeks the queue and, when nothing is deliverable, releases the flag again. The existing re-check only covered the case of a batch that was already queued and became ready in the meantime; when the queue looked empty atpeek()time the method returned without looking again.That leaves a lost wakeup. While the flag is held, the gRPC thread can offer an already decoded (
RAW) batch inaddBatchesand callsendDataToReadersIfNeeded, whosecompareAndSetfails and is silently dropped. The batch is then never delivered, its read future never completes, theallOfinReadSession.onReadResponsenever fires and the session stops sendingReadRequests- the reader stalls forever.Re-read the head of the queue after releasing the flag instead of re-testing the batch captured before it, and turn the retry into a loop so a burst of these hand-offs cannot nest recursively.