Re: stats collector process high CPU utilization

From: "Merlin Moncure" <mmoncure(at)gmail(dot)com>
To: "Tom Lane" <tgl(at)sss(dot)pgh(dot)pa(dot)us>
Cc: "Benjamin Minshall" <minshall(at)intellicon(dot)biz>, pgsql-performance(at)postgresql(dot)org
Subject: Re: stats collector process high CPU utilization
Date: 2007-03-02 01:30:00
Message-ID: b42b73150703011730s7c6d4aaeo8d9206eab2594329@mail.gmail.com
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On 3/2/07, Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> wrote:
> "Merlin Moncure" <mmoncure(at)gmail(dot)com> writes:
> > On 3/1/07, Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> wrote:
> >> A further report led us to realize that 8.2.x in fact has a nasty bug
> >> here: the stats collector is supposed to dump its stats to a file at
> >> most every 500 milliseconds, but the code was actually waiting only
> >> 500 microseconds :-(. The larger the stats file, the more obvious
> >> this problem gets.
>
> > I think this explains the trigger that was blowing up my FC4 box.
>
> I dug in the archives a bit and couldn't find the report you're
> referring to?

I was referring to this:
http://archives.postgresql.org/pgsql-hackers/2007-02/msg01418.php

Even though the fundamental reason was obvious (and btw, I inherited
this server less than two months ago), I was still curious what was
making 8.2 blow up a box that was handling a million tps/hour for over
a year. :-)

merlin

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