From: Andres Freund <andres@2ndquadrant.com>
Organization: 2ndquadrant.com
To: pgsql-general@postgresql.org
Subject: Re: Memory issues
Date: Thu, 27 Sep 2012 08:59:09 +0200
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Cc: Shiran Kleiderman <shirank1@gmail.com>
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On Monday, September 24, 2012 08:45:06 AM Shiran Kleiderman wrote:
> Hi,
> I'm using and Amazon ec2 instance with the following spec and the
> application that I'm running uses a postgres DB 9.1.
> The app has 3 main cron jobs.
> 
> *Ubuntu 12, High-Memory Extra Large Instance
> 17.1 GB of memory
> 6.5 EC2 Compute Units (2 virtual cores with 3.25 EC2 Compute Units each)
> 420 GB of instance storage
> 64-bit platform*
> 
> I've changed the main default values under file *postgresql.conf* to:
> shared_buffers = 4GB
> work_mem = 16MB
> wal_buffers = 16MB
> checkpoint_segments = 32
> effective_cache_size = 8GB
> 
> When I run the app, after an hour or two, free -m looks like below ans the
> crons can't run due to memory loss or similar (i'm new to postgres and db
> admin).
> Thanks!
> 
> free -m, errors:
> 
> total used free shared buffers cached
> Mem: 17079 13742 3337 0 64 11882
> -/+ buffers/cache: 1796 15283
> Swap: 511 0 511
> 
> total used *free* shared buffers cached
> Mem: 17079 16833 *245 *0 42 14583
> -/+ buffers/cache: 2207 14871
> Swap: 511 0 511
> 
> **free above stays low even when nothing is running.
> 
> **errors:
> *DBI connect('database=---;host=localhost','postgres',...) failed: could
> not fork new process for connection: Cannot allocate memory*
> could not fork new process for connection: Cannot allocate memory
> 
> and
> execute failed: ERROR: out of memory
> DETAIL: Failed on request of size 968. [for Statement "
> SELECT DISTINCT....
could you show cat /proc/meminfo?

Greetings,

Andres
-- 
 Andres Freund	                   http://www.2ndQuadrant.com/
 PostgreSQL Development, 24x7 Support, Training & Services