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Subject: Re: Memory leak in pg_stat_statements when qtext file contains
 invalid encoding
From: Daniel Gustafsson <daniel@yesql.se>
In-Reply-To: <CAP53Pky1575W1euSUwj2Zc5b0kBFZqpNuvMOGCvU_bR1tmD7zA@mail.gmail.com>
Date: Fri, 27 Mar 2026 09:51:37 +0100
Cc: Gaurav Singh <gaurav.singh@yugabyte.com>,
 pgsql-bugs@lists.postgresql.org
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To: Lukas Fittl <lukas@fittl.com>
Archived-At: <https://www.postgresql.org/message-id/91A12197-68B4-4C9E-8F5B-DB26D9FA30C5%40yesql.se>
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> On 27 Mar 2026, at 09:21, Lukas Fittl <lukas@fittl.com> wrote:

> But I think you're correct about qbuffer - because that buffer is
> using malloc (not palloc), its not part of any memory context, and so
> it will happily leak on abort.
> 
> It appears our use of malloc in pg_stat_statements is so that we can
> fail on OOM and return NULL without a jump. I think that makes sense
> for when a GC cycle was triggered during regular query execution
> (since we don't want to error the original query), but it seems like
> just bubbling up the OOM if needed when querying the
> pg_stat_statements function seems fine.

We could also use palloc_extended() with MCXT_ALLOC_NO_OOM to avoid erroring
out on OOM and be able to return NULL?

--
Daniel Gustafsson