Re: [PERFORM] Postgres uses too much RAM - Mailing list pgsql-performance

From Merlin Moncure
Subject Re: [PERFORM] Postgres uses too much RAM
Date
Msg-id CAHyXU0wq-hh-CWWFsA6g3c0OBLw2h3pxmwWsDe+GbGH6mhaqcA@mail.gmail.com
Whole thread Raw
In response to [PERFORM] Postgres uses too much RAM  (Hans Braxmeier <hans.braxmeier@outlook.com>)
List pgsql-performance
On Mon, May 8, 2017 at 3:23 PM, Hans Braxmeier
<hans.braxmeier@outlook.com> wrote:
> Hello,
>
>
> on our old server (120 GB RAM) PostgreSQL 9.4.5 was using less than 10 GB of
> ram. On our new server (same system) Postgres 9.4.11 is using up to 40 GB
> Ram. Especially each idle process is consuming 2.4 GB: postgres  30764  8.3
> 2.4 3358400 3215920 ? Ss 21:58 0:24 postgres: testuser testdb [local] idle
>
>
> Summing up PG needs currently 72.14GB (also the slab_cache was increasing
> from 20 GB to 40 GB. ). For monitoring we are using munin. Is this a bug of
> 9.4.11 or what could be wrong?

can you paste unredacted snippet from, say, 'top'?   A common
measuring error is to assume that shared memory usage is specific
cumulative to each process rather than from a shared pool.  It's hard
to say either way from your info above.

If you do have extremely high resident memory usage, culprits might be:
*) bona fide memory leak (although this is rare)
*) bloat in the cache context (relcache, plancache, etc), especially
if you have huge numbers of tables.  workaround is to recycle
processes occasionally and/or use pgbouncer
*) 3rd party package attached to the postgres process (say, pl/java).

merlin


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