Horton

Re: Outdated comments about proc->sem in lwlock.c

Thomas Munro <thomas.munro@gmail.com>

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From: Thomas Munro <thomas.munro@gmail.com>
To: pgsql-hackers <pgsql-hackers@postgresql.org>
Date: 2021-06-03T02:07:02Z
Lists: pgsql-hackers

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On Wed, Mar 10, 2021 at 1:11 AM Thomas Munro <thomas.munro@gmail.com> wrote:
> In passing I noticed that lwlock.c contains 3 comments about bogus
> wakeups due to sharing proc->sem with the heavyweight lock manager and
> ProcWaitForSignal.  Commit 6753333f55e (9.5) switched those things
> from proc->sem to proc->procLatch.  ProcArrayGroupClearXid() and
> TransactionGroupUpdateXidStatus() also use proc->sem though, and I
> haven't studied how those might overlap with with LWLockWait(), so I'm
> not sure what change to suggest.

Here's a patch to remove the misleading comments.

Commits

  1. Remove more obsolete comments about semaphores.

  2. Move deadlock and other interrupt handling in proc.c out of signal handlers.