Fix channel-open cancellation deadlock in ConnectionService - #154
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jpablo2002 merged 4 commits intoJul 24, 2026
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…ion after releasing the lock. ConnectionService.HandleMessageAsync was disposing a pending channel's CancellationTokenRegistration while holding lockObject, but the callback registered in OpenChannelAsync also took lockObject, and Dispose() blocks until an in-flight callback completes — so a channel-open cancelling at that moment deadlocked the session and leaked every later OpenChannelAsync thread.
…ancellation deadlock, using a small internal ConnectionService hook reached by reflection (matching how ReconnectTests reaches KeyRotationThreshold) to force the cancel-during-confirmation race.
adamasmar
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klvnraju
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…ook with an explicit synchronization handshake using TaskCompletionSource and CancellationToken LIFO callback ordering. A second callback registered after the internal one fires first (LIFO), and once it completes, Cancel() immediately proceeds to the internal callback on the same thread — which blocks on lockObject.
klvnraju
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plequere-ms
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… (FIFO) by replacing Thread.Sleep with a dual-registration handshake using TaskCompletionSource.
klvnraju
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Jul 24, 2026
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Problem
ConnectionService.HandleMessageAsyncdisposed a pending channel'sCancellationTokenRegistrationwhile holding
lockObject. The callback registered inOpenChannelAsyncalso takeslockObject,and
Dispose()blocks until an in-flight callback completes. So an open cancelling exactly as itsconfirmation was processed deadlocked the pump thread, hanging every later
OpenChannelAsyncFix
Dispose the registration after releasing the lock. Removing the pending channel under the lock
makes the callback a no-op, so deferring the dispose is safe. Applied to the confirmation and
failure handlers.
Tests
Added
OpenChannelCancelDuringConfirmationDoesNotDeadlockandSessionRemainsUsableAfterOpenCancelRace,which force the race via a small internal hook reached by reflection (like
ReconnectTestsdoes forKeyRotationThreshold).