Re: Kernel kills postgres process - help need

Le mercredi 09 janvier 2008, Jeff Davis a écrit :
> On Wed, 2008-01-09 at 22:57 +0100, Hervé Piedvache wrote:
> > Hi,
> >
> > I have a big trouble with a PostgreSQL server ... regulary since I have
> > added 8 Gb of memory, on a server having already 8Gb of memory, I have
> > troubles. Nothing else have changed ... I'm on a Dell server, and all the
> > memory diagnostics from Dell seems to be good ...
> > When I have a lot of connexions (persistante connexions from 6 web
> > apache/php serveurs using PDO, about 110 process on each web servers) on
> > the server, or long request, it's difficult for me to know when it's
> > appening, the kernel seems to kill my postgresql process then the server
> > become completly instable, and most of the time need a reboot ...
> >
> > I'm on Linux kernel 2.6.15 with a version 8.1.10 of PostgreSQL.
> > My database is a size of 56G
> > RAM = 16 Gb
>
> [snip]
>
> > Jan 9 20:30:47 db2 kernel: oom-killer: gfp_mask=0x84d0, order=0
>
> It looks like the Out Of Memory Killer was invoked, and you need to find
> out why it was invoked.
>
> I posted to LKML here:
>
> http://kerneltrap.org/mailarchive/linux-kernel/2007/2/12/54202
>
> because linux has a behavior -- which in my opinion is a bug -- that
> causes the OOM killer to almost always kill PostgreSQL first, regardless
> of whether it was truly the offending process or not.
>
> So, find out which process truly caused the memory pressure that lead to
> the OOM being invoked, and fix that problem.

How can I process to find this ? It's a production server for a web service,
and I have no idea how to find wich process was the cause of this ... !?

> You may also consider some other linux configuration options that make
> invocation of OOM killer less likely.

On this server there is only Postgresql, slony, and sshd running the rest is
only Linux basic process (cron, atd, getty etc.)

regards,
--
Hervé Piedvache