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https://issues.apache.org/jira/browse/PROTON-2483?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17474952#comment-17474952
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ASF subversion and git services commented on PROTON-2483:
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Commit c6db2b089c6c40c46b5e37a701164bbce3f5ebf9 in qpid-proton's branch
refs/heads/main from Clifford Jansen
[ https://gitbox.apache.org/repos/asf?p=qpid-proton.git;h=c6db2b0 ]
PROTON-2483: epoll proactor TSAN race - ensure task locks not held when calling
pni_timer_set()
> TSAN reported potential deadlock in epoll proactor when run via Qpid Dispatch
> router.
> -------------------------------------------------------------------------------------
>
> Key: PROTON-2483
> URL: https://issues.apache.org/jira/browse/PROTON-2483
> Project: Qpid Proton
> Issue Type: Bug
> Components: proton-c
> Affects Versions: proton-c-0.36.0
> Environment: linux epoll
> Reporter: Clifford Jansen
> Assignee: Clifford Jansen
> Priority: Major
> Attachments: tsan_out.txt
>
>
> The traces are incomplete but the 4 way thread tangle can be inferred as
> follows:
> A: pn_proactor_set_timeout() (p->task.mutex + tm->task.mutex)
> B: pni_timer_manager_process() (tm->task.mutex + tm->deletion_mutex)
> C: pni_connection_timeout() (tm->deletion_mutex + pc1->task.mutex)
> D: proactor_remove() (pc1->task.mutex + p->task.mutex)
> While this particular trace is a false positive (D occurs after all other
> threads have been joined and there are no competing threads to complete the
> circle), the lock ordering is clearly asking for eventual trouble.
> The proactor set_timeout and cancel_timeout API calls do not need to hold the
> proactor task lock while interacting with the timer manager, but do so as a
> convenience to prevent collisions between simultaneous sets/cancels. A
> separate lock can achieve that purpose, stopping A from participating in the
> potential deadlock.
>
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