core: Fix inFlightSubStreams counting on retry commit #12649
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Under certain retry and deadline timings, RetriableStream could leave the response future incomplete because inFlightSubStreams was not decremented consistently during commit. The change ensures inFlightSubStreams is decremented whenever a scheduled retry is committed, restoring correct close signaling without altering retry semantics.
becomeStar
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Feb 7, 2026
| final Future<?> retryFuture; | ||
| final boolean retryWasScheduled = scheduledRetry != null; | ||
| if (scheduledRetry != null) { | ||
| retryFuture = scheduledRetry.markCancelled(); |
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markCancelled() may return null if the scheduled retry was cancelled before setFuture() was called.
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Yes, when the hang occurs I see markCancelled() had returned null causing the code in CommitTask to skip closing the master listener.
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/gcbrun |
kannanjgithub
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Feb 9, 2026
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This PR fixes a race condition in RetriableStream where, under certain retry and deadline timings, the response future may never be completed.
When a deadline cancellation occurs concurrently with retry commit, inFlightSubStreams may not be decremented, causing
ClientCallImpl.ClientStreamListenerImpl.closedto never be invoked. As a result, blockingUnaryCall can hang indefinitely.After this change, the inFlightSubStreams counting is consistent whenever a scheduled retry is committed, ensuring the close signal is always delivered.
I verified this using the issue reproduction code from the issue reporter, which previously caused blockingUnaryCall to hang and eventually hit a TimeoutException because a while loop never progressed. After this change, running the same reproduction code no longer hangs and continues as expected without timing out.
Fixes #12620