sleep(3) sometimes too sleepy on FreeBSD 8.0?

[John Marshall]

On Tue, 23 Feb 2010, 11:36 +0200, Kostik Belousov wrote:
> On Tue, Feb 23, 2010 at 12:35:22PM +1100, John Marshall wrote:
> > Environment: sendmail 8.14.4 on FreeBSD 8.0-RELEASE-p2
> > 
> > Since upgrading a few local servers to FreeBSD 8.0-RELEASE (and
> > subsequently 8.0-RELEASE-p2), I have been seeing VERY intermittent
> > problems with sendmail persistent queue runners.  One or more queue
> > runners will fail to wake up (having been told to sleep for either 1 or
> > 5 seconds) and mail accumulates in their queue group queues.
> > 
> > I have only seen this about 4 times but at least once on each of the
> > three 8.0 servers.  I've been seeing something like one occurrence per
> > fortnight overall.  The first few times I re-started sendmail.  On
> > Saturday I spent longer looking at it.
> 
> I think the best way to collect the data would be ktrace the queue runners,
> preferrably starting the ktrace before they are stuck.

OK.  I've caught one of them (different server from Saturday).

  PID  TT  STAT      TIME COMMAND
48501  ??  Ss     0:14.77 sendmail: accepting connections (sendmail)
48502  ??  S      1:00.24 sendmail: running queue: /var/spool/mqueue/qd1/df (sendmail)
48503  ??  S      0:38.11 sendmail: running queue: /var/spool/mqueue/mby/df (sendmail)
48504  ??  I      0:27.34 sendmail: running queue: /var/spool/mqueue/oz/df (sendmail)
48505  ??  S      0:37.59 sendmail: running queue: /var/spool/mqueue/rw2/df (sendmail)
48506  ??  S      0:34.93 sendmail: running queue: /var/spool/mqueue/hold/df (sendmail)

My ktrace file was created with 'ktrace -g 48501'.  I have the result of
'kdump -R -p 48504' available at:

 <http://www.riverwillow.net.au/~john/8_0/rwsrv04_201002240725.kdump.gz>

The affected queue group was empty.  I have redirected messages for that
domain to a different queue group so that I can leave that queue runner
stuck.

-- 
John Marshall
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