Horton

Re: pg_walinspect memory leaks

Andres Freund <andres@anarazel.de>

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From: Andres Freund <andres@anarazel.de>
To: Peter Geoghegan <pg@bowt.ie>
Cc: Bharath Rupireddy <bharath.rupireddyforpostgres@gmail.com>, Jeff Davis <pgsql@j-davis.com>, PostgreSQL Hackers <pgsql-hackers@lists.postgresql.org>
Date: 2023-02-14T00:55:37Z
Lists: pgsql-hackers 
Hi,

On 2023-02-13 15:22:02 -0800, Peter Geoghegan wrote:
> More concretely, it looks like GetWALRecordInfo() calls
> CStringGetTextDatum/cstring_to_text in a way that accumulates way too
> much memory in ExprContext.

Additionally, we leak two stringinfos for each record.


> This could be avoided by using a separate memory context that is reset
> periodically, or something else along the same lines.

Everything other than a per-row memory context that's reset each time seems
hard to manage in this case.

Somehwat funnily, GetWALRecordsInfo() then ends up being unnecessarily
dilligent about cleaning up O(1) memory, after not caring about O(N) memory...

Greetings,

Andres Freund

Commits

  1. Limit memory usage of pg_walinspect functions.