| From: | Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> | 
|---|---|
| To: | Craig Ringer <craig(at)postnewspapers(dot)com(dot)au> | 
| Cc: | paulo matadr <saddoness(at)yahoo(dot)com(dot)br>, GENERAL <pgsql-general(at)postgresql(dot)org> | 
| Subject: | Re: Understand this error | 
| Date: | 2009-05-01 15:50:21 | 
| Message-ID: | 13161.1241193021@sss.pgh.pa.us | 
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| Lists: | pgsql-general | 
Craig Ringer <craig(at)postnewspapers(dot)com(dot)au> writes:
> Note that it's not very likely that PostgreSQL was the process that used
> up all your memory. It was just unlucky enough to be picked as the one
> to be killed, because the OOM killer is terrible at estimating which
> process is using the most memory when programs like PostgreSQL have
> allocated large blocks of shared memory.
It's worse than that: the OOM killer is broken by design, because it
intentionally picks on processes that have a lot of large children
--- without reference to the fact that a lot of the "largeness" might
be the same shared memory block.  So the postmaster process very often
looks like a good target to it, even though killing the postmaster will
in fact free a negligible amount of memory.
regards, tom lane
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