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From: Tomas Vondra <[email protected]>
To: Aleš Zelený <[email protected]>
To: pgsql-generallists.postgresql.org <[email protected]>
Subject: Re: PostgreSQL 17.5 - could not map dynamic shared memory segment
Date: Sun, 22 Jun 2025 00:44:36 +0200
Message-ID: <[email protected]> (raw)
In-Reply-To: <CAODqTUaYHVKWFitXQvdhn0jrmVL60=bTp=eOAX2dR7x0ymZshQ@mail.gmail.com>
References: <CAODqTUaYHVKWFitXQvdhn0jrmVL60=bTp=eOAX2dR7x0ymZshQ@mail.gmail.com>

On 6/21/25 23:09, Aleš Zelený wrote:
> Hello,
> ...
>
> The application benefits from parallel queries, so despite the first
> temptation to disable parallel queries (based on log entries correlation
> only, but is that the root cause?) I did not want to disable parallel
> queries, if there is another workaround/solution/fix available.
> 
> Thanks for any hints on how to provide more information if needed, as
> well as for fix/workaround advice.
> 

Could it be that you simply ran out of memory, or perhaps hit the
overcommit? What does sysctl say?

  sysctl vm.overcommit_memory

And what's CommitLimit/Committed_AS in /proc/meminfo? IIRC the shmem is
counted against the limit, and if the system does not have significant
swap, it's not uncommon to hit that (esp. with overcommit_memory=2).


regards

-- 
Tomas Vondra

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