Fix the deadlock caused by the ImagePullDeleteLock #836
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samuelkarp
approved these changes
Jun 8, 2017
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These changes should eliminate the deadlock we encountered with #833 |
LGTM
petderek
approved these changes
Jun 9, 2017
| seelog.Debug("Attempting to obtain ImagePullDeleteLock for removing images") | ||
| ImagePullDeleteLock.Lock() | ||
| seelog.Debug("Obtained ImagePullDeleteLock for removing images") | ||
| defer seelog.Debug("Released ImagePullDeleteLock after removing images") |
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Maybe group these statements in an anonymous function so its easier to see the order of execution?
defer func() { ... }
| // Cause a fake delay when recording container reference so that the | ||
| // race condition between ImagePullLock and updateLock gets exercised | ||
| // If updateLock precedes ImagePullLock, it can cause a deadlock | ||
| client.EXPECT().InspectImage(sleepContainer.Image).Do(func(image string) { |
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Cool! Did we verify that this fails before the patch?
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Yes, this test doesn't pass without the patch.
Merged
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Summary
Fix a dead lock that was caused by the ImageCleanup and Image Pull. Issue #833
Implementation details
Based on the explanation here, adjust the order of lock acquiring in image cleanup, so that both go routines will require the lock in the same order, which wouldn't cause deadlock.
Testing
make release)go build -out amazon-ecs-agent.exe ./agent)make test) passgo test -timeout=25s ./agent/...) passmake run-integ-tests) pass.\scripts\run-integ-tests.ps1) passmake run-functional-tests) pass.\scripts\run-functional-tests.ps1) passNew tests cover the changes:
Description for the changelog
Fix an issue which could potentially cause agent running into deadlock.
Licensing
This contribution is under the terms of the Apache 2.0 License:
yes