Re: vacuum slowed by syslogd

From: Michael Adler <adler(at)pobox(dot)com>
To: Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>
Cc: pgsql-admin(at)postgresql(dot)org
Subject: Re: vacuum slowed by syslogd
Date: 2004-01-14 21:46:18
Message-ID: 20040114214618.GA26619@pobox.com
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On Tue, Jan 13, 2004 at 11:36:19PM -0500, Tom Lane wrote:
> Michael Adler <adler(at)pobox(dot)com> writes:
> > On many occasions, I've noticed that some PostgreSQL activity takes
> > far longer than it previously did and that disabling syslogd addresses
> > the symptoms.
> > ...
> > This evidence normally indicates a name resolution issue, but I'm not
> > sure how to test for that beyond using "hostname -v -i".
>
> I looked in Red Hat's bugzilla for similar issues, and found a mention
> that syslogd tries to reverse-lookup the address it gets each message
> from. A delay there could act as you describe. At least in recent RH
> releases, you can start syslogd with the "-x" switch to disable this
> lookup --- does that exist in Debian, and if so does it help?

There is no such option within Debian or the syslogd from freshmeat. Sounds nice, though.

I was able to track down a name resolution issue. The "nameserver" in /etc/resolv.conf pointed to a nonexistent host. This added ten second delays to telnetd logins and netstat -a. This seemed to be the heart of the problem, but I'm getting some mixed info from the "field" and I'm still following up.

Thanks,
Mike

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