Horton

Re: per backend I/O statistics

Bertrand Drouvot <bertranddrouvot.pg@gmail.com>

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From: Bertrand Drouvot <bertranddrouvot.pg@gmail.com>
To: Michael Paquier <michael@paquier.xyz>
Cc: Nazir Bilal Yavuz <byavuz81@gmail.com>, Alvaro Herrera <alvherre@alvh.no-ip.org>, Kyotaro Horiguchi <horikyota.ntt@gmail.com>, pgsql-hackers@lists.postgresql.org
Date: 2024-12-19T06:12:04Z
Lists: pgsql-hackers 
Hi,

On Thu, Dec 19, 2024 at 01:21:54PM +0900, Michael Paquier wrote:
> 
> While doing more tests with backends exiting concurrently with their
> stats scanned, I have detected one path in pg_stat_get_backend_io()
> after calling pgstat_get_beentry_by_proc_number() where we should also
> check that it does not return NULL, or we would crash on a pointer
> dereference when reading the backend type.
> 
> Fixed that,

Oh right, indeed all the others pgstat_get_beentry_by_proc_number() callers are
checking for a NULL returned value.

> bumped the two version counters, and done.

Thanks!

I think I'll start a dedicated thread to discuss the stats_fetch_consistency/'snapshot'
point (will be easier to follow than resuming the discussion in this thread).

Regards,

-- 
Bertrand Drouvot
PostgreSQL Contributors Team
RDS Open Source Databases
Amazon Web Services: https://aws.amazon.com

Commits

  1. Rework handling of pending data for backend statistics

  2. Rename some pgstats callbacks related to flush of entries

  3. Relax regression test for fsync check of backend-level stats

  4. Add backend-level statistics to pgstats

  5. Extract logic filling pg_stat_get_io()'s tuplestore into its own routine

  6. Tweak some comments related to variable-numbered stats in pgstat.c