Horton

Re: Memory leak in WAL sender with pgoutput (v10~)

Alvaro Herrera <alvherre@alvh.no-ip.org>

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From: Alvaro Herrera <alvherre@alvh.no-ip.org>
To: Michael Paquier <michael@paquier.xyz>
Cc: Postgres hackers <pgsql-hackers@lists.postgresql.org>, Amit Kapila <amit.kapila16@gmail.com>
Date: 2024-11-30T08:28:31Z
Lists: pgsql-hackers

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On 2024-Nov-30, Michael Paquier wrote:

> After sleeping on that, and because the leak is minimal, I'm thinking
> about just applying the fix only on HEAD and call it a day.  This
> changes the structure of Publication so as we use a char[NAMEDATALEN]
> rather than a char*, avoiding the pstrdup(), for the publication name
> and free it in the list_free_deep() when reloading the list of
> publications.

I'm not sure about your proposed fix.  Isn't it simpler to have another
memory context which we can reset instead of doing list_free_deep()?  It
doesn't have to be a global memory context -- since this is not
reentrant and not referenced anywhere else, it can be a simple static
variable in that block, as in the attached.  I ran the stock tests (no
sysbench) and at least it doesn't crash.

This should be easily backpatchable also, since there's no ABI change.

-- 
Álvaro Herrera        Breisgau, Deutschland  —  https://www.EnterpriseDB.com/

Commits

  1. Fix memory leak in pgoutput with relation attribute map

  2. Fix memory leak in pgoutput with publication list cache

  3. Allow specifying row filters for logical replication of tables.