Horton

Outdated comments about proc-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: 2021-03-09T12:11:59Z
Lists: pgsql-hackers 
Hi,

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.

Commits

  1. Remove more obsolete comments about semaphores.

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