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help / color / mirror / Atom feedFrom: Ron Johnson <[email protected]>
To: pgsql-general <[email protected]>
Subject: Re: Vacuum full connection exhaustion
Date: Fri, 9 Aug 2024 00:15:33 -0400
Message-ID: <CANzqJaDZDLnYhPEds8jMf4ArEG1MOVtiPr7g0GvPMiEpjrNqiQ@mail.gmail.com> (raw)
In-Reply-To: <[email protected]>
References: <CAJ+5Ff6WtFCzamrRZqN3u3htvkGcmob7VaYWYBd+sRx6jKpHuA@mail.gmail.com>
<[email protected]>
On Thu, Aug 8, 2024 at 10:12 AM Christophe Pettus <[email protected]> wrote:
>
>
> > On Aug 7, 2024, at 10:34, Costa Alexoglou <[email protected]> wrote:
> >
> > Hey folks,
> >
> > I noticed something weird, and not sure if this is the expected
> behaviour or not in PostgreSQL.
> >
> > So I am running Benchbase (a benchmark framework) with 50 terminals (50
> concurrent connections).
> > There are 2-3 additional connections, one for a postgres-exporter
> container for example.
> >
> > So far so good, and with a `max_connections` at 100 there is no problem.
> What happens is that if I execute manually `VACUUM FULL` the connections
> are exhausted.
>
> VACUUM FULL takes an exclusive lock on the table that it is operating on.
> It's possible that a connection becomes blocked on that exclusive lock
> waiting for the VACUUM FULL to finish, the application sees the connection
> stopped and fires up another one (this is common in container-based
> applications), that one blocks... until all of the connections are full of
> queries waiting on that VACUUM FULL.
>
>
"I see a lock, so let's cause another one!" That's crazy.
--
Death to America, and butter sauce.
Iraq lobster!
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Subject: Re: Vacuum full connection exhaustion
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