Fix Potential deadlock in AutorecoveringConnection #649
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…ts consumers and recordedQueues. Having one order avoids circular wait.
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While investigating this I have found out that 1aad565 addressed this in a different place. I now wonder whether |
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To answer my own question: it seems to be a copy-and-paste artefact. |
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So the right thing to do is to not acquire a lock on |
michaelklishin
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Apr 22, 2020
…ot need to acquire a lock on this.consumers It most likely was a copy-paste artefact introduced back in 2013-2014. AutorecoveringConnection.maybeDeleteRecordedAutoDeleteQueue does need to lock this.consumers as conditional queue deletion does need to check the number of known consumers on that queue. 1aad565 addressed a potential deadlock caused by the unsafe order of lock acquisitions. In #648 another similar issue was discovered which #649 tried to address by acquiring a lock on this.consumers early. However, exchange cleanup does not need to lock this.consumers as it does not mutate it. Closes #648.
michaelklishin
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Apr 22, 2020
…ot need to acquire a lock on this.consumers It most likely was a copy-paste artefact introduced back in 2013-2014. AutorecoveringConnection.maybeDeleteRecordedAutoDeleteQueue does need to lock this.consumers as conditional queue deletion does need to check the number of known consumers on that queue. 1aad565 addressed a potential deadlock caused by the unsafe order of lock acquisitions. In #648 another similar issue was discovered which #649 tried to address by acquiring a lock on this.consumers early. However, exchange cleanup does not need to lock this.consumers as it does not mutate it. Closes #648. (cherry picked from commit 5c3fce8)
acogoluegnes
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Apr 27, 2020
…ot need to acquire a lock on this.consumers It most likely was a copy-paste artefact introduced back in 2013-2014. AutorecoveringConnection.maybeDeleteRecordedAutoDeleteQueue does need to lock this.consumers as conditional queue deletion does need to check the number of known consumers on that queue. 1aad565 addressed a potential deadlock caused by the unsafe order of lock acquisitions. In #648 another similar issue was discovered which #649 tried to address by acquiring a lock on this.consumers early. However, exchange cleanup does not need to lock this.consumers as it does not mutate it. Closes #648. (cherry picked from commit 5c3fce8)
acogoluegnes
pushed a commit
that referenced
this pull request
Apr 27, 2020
…ot need to acquire a lock on this.consumers It most likely was a copy-paste artefact introduced back in 2013-2014. AutorecoveringConnection.maybeDeleteRecordedAutoDeleteQueue does need to lock this.consumers as conditional queue deletion does need to check the number of known consumers on that queue. 1aad565 addressed a potential deadlock caused by the unsafe order of lock acquisitions. In #648 another similar issue was discovered which #649 tried to address by acquiring a lock on this.consumers early. However, exchange cleanup does not need to lock this.consumers as it does not mutate it. Closes #648. (cherry picked from commit 5c3fce8)
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Fixes #648
Ensuring we have only one order of acquiring synchronization on objects
consumersandrecordedQueues. Having one order avoids circular wait.