Date: Thu, 16 Jan 2025 06:48:58 +0000
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,
	Andres Freund <andres@anarazel.de>
Subject: Re: per backend I/O statistics
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Hi,

On Thu, Jan 16, 2025 at 09:55:10AM +0900, Michael Paquier wrote:
> On Wed, Jan 15, 2025 at 05:20:57PM +0300, Nazir Bilal Yavuz wrote:
> > I think allowing only pgStatPendingContext to have
> > MemoryContextAllowInCriticalSection() is not enough. We need to allow
> > at least pgStatSharedRefContext as well to have
> > MemoryContextAllowInCriticalSection() as it can be allocated too.
> > 
> > '''
> > pgstat_prep_pending_entry() ->
> > pgstat_get_entry_ref() ->
> > pgstat_get_entry_ref_cached() ->
> > MemoryContextAlloc(pgStatSharedRefContext, sizeof(PgStat_EntryRef))
> > '''
> 
> Yep, I was pretty sure that we have a bit more going on.  Last time I
> began digging into the issue I was loading injection_points in
> shared_preload_libraries with stats enabled to see how much I could
> break, and this was one pattern once I've forced the pending part.  I
> didn't get through the whole exercise.

I'll look at it and come back with a proposal as part of [1].

[1]: https://www.postgresql.org/message-id/Z4dRlNuhSQ3hPPv2@paquier.xyz

Regards,

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