Horton

Re: straightening out backend process startup

Tom Lane <tgl@sss.pgh.pa.us>

View thread View on postgr.es
From: Tom Lane <tgl@sss.pgh.pa.us>
To: Andres Freund <andres@anarazel.de>
Cc: pgsql-hackers@postgresql.org
Date: 2021-08-02T16:57:36Z
Lists: pgsql-hackers 
Andres Freund <andres@anarazel.de> writes:
> I think there's quite a few different issues around this - here I'm just
> trying to tackle a few of the most glaring (to me):

No opinion yet about most of this, but I did want to react to

> In fact, I think there's a good argument to be made that we should
> entirely remove the concept of BackendIds and just use pgprocnos. We
> have a fair number of places like SignalVirtualTransaction() that need
> to search the procarray just to find the proc to signal based on the
> BackendId. If we used pgprocno instead, that'd not be needed.

If I understand what you're suggesting, it'd result in unused slots
in sinvaladt.c's procState[] array, which could create an annoying
drag on performance.  However, I think it might be reasonable to
switch other things over to using pgprocnos, with an eye to
eventually making BackendIds private to the sinval mechanism.
There's certainly no strong reason why sinval's array indexes
need to be used as identifiers by other modules.

			regards, tom lane

Commits

  1. process startup: Split single user code out of PostgresMain().

  2. process startup: Do InitProcess() at the same time regardless of EXEC_BACKEND.

  3. process startup: Initialize PgStartTime earlier in single user mode.

  4. pgstat: Schedule per-backend pgstat shutdown via before_shmem_exit().

  5. pgstat: Bring up pgstat in BaseInit() to fix uninitialized use of pgstat by AV.

  6. process startup: Always call Init[Auxiliary]Process() before BaseInit().

  7. process startup: Centralize pgwin32_signal_initialize() calls.

  8. process startup: Remove bootstrap / checker modes from AuxProcType.

  9. process startup: Move AuxiliaryProcessMain into its own file.

  10. process startup: auxprocess: reindent block

  11. process startup: Separate out BootstrapModeMain from AuxiliaryProcessMain.

  12. process startup: Rename postmaster's --forkboot to --forkaux.