Release throttle permits only once#2280
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hyperxpro merged 1 commit intoJul 24, 2026
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A completion callback can reentrantly trigger onThrowable when a reactive subscriber disposes and cancels its future. ReleasePermitOnComplete then released the same acquired permit from both terminal callbacks, inflating the semaphore and overflowing when its count reached Integer.MAX_VALUE. Guard the release atomically while continuing to forward both callbacks to the wrapped handler. Add a regression test reproducing the reported completion-to-cancellation callback sequence. Fixes AsyncHttpClient#1797 Codex on behalf of Pavel Ptashyts Co-Authored-By: Codex <[email protected]>
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Motivation: PR #2280 covered the reentrant release case, but left several permit-release paths untested. In particular, non-reentrant callback paths and concurrent double-release races were not verified. Modification: Add four tests to `ReleasePermitOnCompleteTest` covering the `onCompleted()` exception path, single-callback release baselines, and a concurrent cross-thread double-release race. Result: Better test coverage for edge cases
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Summary
Root cause
ReleasePermitOnCompletereleased the same acquired permit from bothonCompletedandonThrowable. A completion callback can synchronously cancelits future and reenter the wrapper through
onThrowable, causing both callbackframes to release the permit. This inflated the semaphore count and raised
java.lang.Error: Maximum permit count exceededat the maximum count.Validation
passed
ClientStatsTesttimeout-boundary failure, and another encountered transienttest-class artifact corruption; the final rerun was stopped at the operator's
request
Closes #1797
Codex on behalf of Pavel Ptashyts