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From: Costa Alexoglou <costa@dbtune.com>
Date: Wed, 7 Aug 2024 19:34:12 +0200
Message-ID: <CAJ+5Ff6WtFCzamrRZqN3u3htvkGcmob7VaYWYBd+sRx6jKpHuA@mail.gmail.com>
Subject: Vacuum full connection exhaustion
To: pgsql-general@lists.postgresql.org
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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.

Also tried this with 150 `max_connections` to see if it just =E2=80=9Cdoubl=
es=E2=80=9D the
current connections, but as it turned out, it still exhausted all the
connections until it reached `max_connections`.

This was cross-checked, as the postgres-exporter could not connect, and I
manually was not allowed to connect with `psql`.

Is this expected or is this a bug?


postgres-exporter logs:
```
sql: error: connection to server on socket
"/var/run/postgresql/.s.PGSQL.5432" failed: FATAL:  sorry, too many clients
already
```

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<div dir=3D"ltr">Hey folks,<br><br>I noticed something weird, and not sure =
if this is the expected behaviour or not in PostgreSQL.<br><br>So I am runn=
ing Benchbase (a benchmark framework) with 50 terminals (50 concurrent conn=
ections).<div>There are 2-3 additional connections, one for a postgres-expo=
rter container for example.<br><br>So far so good, and with a `max_connecti=
ons` at 100 there is no problem. What happens is that if I execute manually=
 `VACUUM FULL` the connections are exhausted.<br><br>Also tried this with 1=
50 `max_connections` to see if it just =E2=80=9Cdoubles=E2=80=9D the curren=
t connections, but as it turned out, it still exhausted all the connections=
 until it reached `max_connections`.<br><br>This was cross-checked, as the =
postgres-exporter could not connect, and I manually was not allowed to conn=
ect with `psql`.<br><br>Is this expected or is this a bug?<br><br><br>postg=
res-exporter logs:<br>```<br>sql: error: connection to server on socket &qu=
ot;/var/run/postgresql/.s.PGSQL.5432&quot; failed: FATAL: =C2=A0sorry, too =
many clients already<br>```<br></div></div>

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