Horton

Re: Interrupts vs signals

Thomas Munro <thomas.munro@gmail.com>

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From: Thomas Munro <thomas.munro@gmail.com>
To: pgsql-hackers <pgsql-hackers@postgresql.org>
Cc: Andres Freund <andres@anarazel.de>, Robert Haas <robertmhaas@gmail.com>, Heikki Linnakangas <hlinnaka@iki.fi>
Date: 2024-07-08T02:56:38Z
Lists: pgsql-hackers

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Here's an updated version of this patch.

The main idea is that SendProcSignal(pid, PROCSIGNAL_XXX, procno)
becomes SendInterrupt(INTERRUPT_XXX, procno), and all the pending
interrupt global variables and pss_procsignalFlags[] go away, along
with the SIGUSR1 handler.  The interrupts are compressed into a single
bitmap.  See commit message for more details.

The patch is failing on Windows CI for reasons I haven't debugged yet,
but I wanted to share what I have so far.  Work in progress!

Here is my attempt to survey the use of signals and write down what I
think we might do about them all so far, to give the context for this
patch:

https://wiki.postgresql.org/wiki/Signals

Comments, corrections, edits very welcome.

Commits

  1. Ignore SIGINT in walwriter and walsummarizer

  2. Split WaitEventSet functions to separate source file

  3. Use ModifyWaitEvent to update exit_on_postmaster_death

  4. Remove unused ShutdownLatchSupport() function

  5. Rename two functions that wake up other processes

  6. Use ProcNumbers instead of direct Latch pointers to address other procs

  7. Clean up WaitLatch calls that passed latch without WL_LATCH_SET

  8. Remove unneeded #include

  9. Remove unused latch

  10. Remove support for background workers without BGWORKER_SHMEM_ACCESS.