Fix flaky PickAsync_UpdateAddressesWhileRequestingConnection_DoesNotDeadlock test#2705
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JamesNK merged 1 commit intogrpc:masterfrom Mar 31, 2026
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…eadlock test The test's MessageLogged callback intercepted every ConnectionRequested log event, but the SyncPoint is a one-shot mechanism. After Continue() is called, subsequent WaitToContinue() calls return immediately. When UpdateAddresses triggers a reconnect that fires additional ConnectionRequested events, the callback re-enters and executes inside the subchannel lock, causing state interleaving that leaves CurrentEndPoint null while the picker is set to PickFirstPicker. PickAsync then waits for a new picker that never arrives. Fix by using Interlocked.CompareExchange to ensure the callback only intercepts ConnectionRequested once, matching the test's intent.
JamesNK
requested review from
BrennanConroy,
ReubenBond,
adityamandaleeka and
asheshvidyut
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The test's
MessageLoggedcallback intercepted everyConnectionRequestedlog event, but theSyncPointis a one-shot mechanism (backed byTaskCompletionSource). AfterContinue()is called, subsequentWaitToContinue()calls return immediately.When
UpdateAddressestriggers a reconnect that fires additionalConnectionRequestedevents, the callback re-enters and executes inside the subchannel lock, causing state interleaving that leavesCurrentEndPointnull while the picker is set toPickFirstPicker.PickAsyncthen waits for a new picker that never arrives, timing out after 5 seconds.Fix: Use
Interlocked.CompareExchangeto ensure the callback only interceptsConnectionRequestedonce, matching the test's intent of pausing exactly one connection request.Verified stable with 100/100 passes in a loop.