ARTEMIS-3622 MQTT can deadlock on client cxn/discxn #4909
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This commit fixes the deadlock described on ARTEMIS-3622 by moving the synchronization "up" a level from the MQTTSession to the MQTTConnectionManager. It also eliminates the synchronization on the MQTTSessionState in the MQTTConnectionManager because it's no longer needed. This change should not only eliminate the deadlock, but improve performance relatively as well. There is no test associated with this commit as I wasn't able to reproduce the deadlock with any kind of straight-forward test. There was a test linked on the Jira, but it involved intrusive and fragile scaffolding and wasn't ultimately tenable. That said, I did test this fix with that test and it was successful. In any case, I think static analysis should be sufficient here as the changes are pretty straight-forward.
gemmellr
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May 15, 2024
...ocol/src/main/java/org/apache/activemq/artemis/core/protocol/mqtt/MQTTConnectionManager.java
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This commit fixes the deadlock described on ARTEMIS-3622 by moving the synchronization "up" a level from the MQTTSession to the MQTTConnectionManager. It also eliminates the synchronization on the MQTTSessionState in the MQTTConnectionManager because it's no longer needed. This change should not only eliminate the deadlock, but improve performance relatively as well.
There is no test associated with this commit as I wasn't able to reproduce the deadlock with any kind of straight-forward test. There was a test linked on the Jira, but it involved intrusive and fragile scaffolding and wasn't ultimately tenable. That said, I did test this fix with that test and it was successful. In any case, I think static analysis should be sufficient here as the changes are pretty straight-forward.