Fix race condition in WaitForInstanceAsync causing intermittent test failures #574
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…End test to fail The original code had a TOCTOU race condition where a completion notification could be missed if the orchestration completed between checking completion status and adding the waiter. The fix reorders the operations to add the waiter first, then check for completion. Co-authored-by: YunchuWang <[email protected]>
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[WIP] Investigate and fix failing testcase in DurableTaskGrpcClientIntegrationTests
Fix race condition in WaitForInstanceAsync causing intermittent test failures
Dec 17, 2025
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LGTM |
YunchuWang
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Dec 17, 2025
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Pull request overview
This PR fixes an intermittent race condition in WaitForInstanceAsync that was causing the RestartAsync_EndToEnd test to fail. The issue occurred when an orchestration completed between checking its status and registering a waiter, resulting in missed completion notifications and 30-second timeouts.
Key Changes:
- Reordered operations in
WaitForInstanceAsyncto register the waiter before checking completion status, eliminating the race condition window - Added clear comments explaining the race condition fix and the two-step registration-then-check pattern
Co-authored-by: Copilot <[email protected]>
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@copilot update pr description to follow .github/PULL_REQUEST_TEMPLATE.md |
halspang
approved these changes
Dec 17, 2025
Copilot stopped work on behalf of
YunchuWang due to an error
December 17, 2025 23:42
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RestartAsync_EndToEnd(restartWithNewInstanceId: True)was failing intermittently due to a TOCTOU race condition inWaitForInstanceAsync.Problem
The original code checked completion status before adding a waiter. If orchestration completed between these two steps, the completion notification was sent to no registered waiter, causing the caller to wait indefinitely (30s timeout).
Fix
Reorder operations to add waiter first, then check status:
This ensures we either:
Original prompt
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