On Sep 26, 2025, at 17:32, Joel Jacobson <joel@compiler.org> wrote:
On Fri, Sep 26, 2025, at 04:26, Chao Li wrote:
I think what you explained is partially correct.
Based on my understanding, any backend process may call SignalBackends(), which means that it’s possible that multiple backend processes may call SignalBackends() concurrently.
Looking at your code, between checking QUEUE_BACKEND_WAKEUP_PENDING_FLAG(i) and set the flag to true, there is a block of code (the “if-else”) to run, so that it’s possible that multiple backend processes have passed the QUEUE_BACKEND_WAKEUP_PENDING_FLAG(i) check, then multiple signals will be sent to a process, which will lead to duplicate timeout enabled in the receiver process.
I don't see how that can happen; we're checking wakeup_pending_flag while holding an exclusive lock, so I don't see how multiple backend processes could be within the region where we check/set wakeup_pending_flag, at the same time?
/Joel
I might miss the factor of holding an exclusive lock. I will revisit that part again.
Best regards,
--
Chao Li (Evan) HighGo Software Co., Ltd. https://www.highgo.com/
