Date: Sat, 21 Dec 2002 15:03:09 +0100
* Robert Collins <robertc@squid-cache.org>:
> > We're encountering sporadic crashes of the squid children (SIGSEGV,
> > signal 11). We were investigating in several directions:
>
> Which squid children?
Dunno. I'm just telling you what squid writes to /var/log/messages
(see below) - it clearly talks of "Squid Parent: child process"!
> Squid only spawns 1 one squid process. If you are using aufs, you may
> see many pids on linux, but that is due to a 'feature' of the linux
> thread support where each thread gets a different pid.
Dec 19 17:21:52 spidergirl -- MARK --
Dec 19 17:41:51 spidergirl -- MARK --
Dec 19 18:01:51 spidergirl -- MARK --
Dec 19 18:06:38 spidergirl squid[2198]: Squid Parent: child process 2200 exited due to signal 11
Dec 19 18:06:41 spidergirl squid[2198]: Squid Parent: child process 2796 started
Dec 19 18:06:42 spidergirl squid[2198]: Squid Parent: child process 2796 exited due to signal 11
Dec 19 18:06:45 spidergirl squid[2198]: Squid Parent: child process 2831 started
> > * the Kernel has highmem support enabled (we have 2GB physical RAM and
> > 4 GB swap)
>
> I've not used linux w/ highmem support - what changes does it make to
> the kernel memory interface?
Dunno.
> > * we closely observed dmesg, messages and syslog. No oddities were
> > found. Squid simply crashes with signal 11.
>
> What about cache.log?
There's no special stuff prior to the crashes. Only our tools querying the stats.
> > * we tried both ufs and aufs as cache filesystems, since the FAQ tells
> > us the async I/O may have bugs. Yet, the crashes still occur.
>
> diskd doesn't have any known bugs, and for any large squid install, ufs
> will perform *very* poorly.
Interesting. Maybe we should switch.
> Squid should trap the crash and log it to cache.log.
It doesn't. It's simply logging the restart, but not the crash!
> > cache_mem 500 MB
> > maximum_object_size 65536 KB
> > cache_dir aufs /squid-cache0 16000 256 256
> > cache_dir aufs /squid-cache1 16000 256 256
>
> This configuration will attempt to use ~ 900Mb of RAM. That should be
> fine.
And alas, this works fine. With "cache_mem 700 MB" it also works
excellently!
> As to your problem, may I suggest the following:
> 1) Use diskd. A nasty aufs bug was found recently that could impact you.
> 2) Check cache.log as your primary source for squid diagnostics.
See attached log - not entirely illuminating (for the unitiated?)
> 3) Check squid memory use via cache manager for statistics.
We're using http://wessels.squid-cache.org/squid-rrd/ to monitor &
graph all kinds of data. I'll attach some pics
> 4) Use squid 2.5-stable-cvs if you really want aufs support, the bug is
> fixed there.
The BUG? Which BUG? :) Note that our problem occurs with both ufs and
aufs.
-- Ralf Hildebrandt (Im Auftrag des Referat V a) Ralf.Hildebrandt@charite.de Charite Campus Mitte Tel. +49 (0)30-450 570-155 Referat V a - Kommunikationsnetze - Fax. +49 (0)30-450 570-916 Deutschland: Kein Weltraum links auf dem Geraet. Pfeife zerbrochen.
Received on Sat Dec 21 2002 - 07:03:13 MST
