Memory Error using Mailman on FreeBSD. How to debug?

Lachlan Michael lachlan at
Fri Feb 8 09:32:50 UTC 2008

>>>How big does the mailman process actually get?  top will tell you.
>>Mailman values don't budge. None of the mailman processes go over about
>>8.5M, which is what they are during idle time.
> Real puzzler.  I'm surprised not to have at least one process growing,
> though.  Maybe it's not using much CPU and you're not spotting it.
> Try running top, then sorting on size (o size inside top) then try your
> mailman email again.  Make sure the top refresh rate is fast enough.  s
> 1 inside top would do that, or even s 0 if desperate.

Following you advice, as far as I can tell, the mailman qrunner process

 /usr/local/bin/python2.5 /usr/local/mailman/bin/qrunner
--runner=IncomingRunner:0:1 -s

is the one that crashes: all other mailman processes are unaffected. I
couldn't see it increase much in size (maybe it went from 8.5M to 12.5M),
then it just bombed and a new process was spawned (easy to tell by the
large increase in PID).

> Other things to try:  Up the stack size
>     ulimit -s 262144
> inside the mailman startup.  Again, I've had processes in the past which
> needed this.
> You'd have to check that from a shell (/bin/sh) and first to see that
> your system will allow a bigger value.  If not, I believe that there is
> a sysctl to do that these days but don't have a modern enough system to
> look it up.  A search for MAXSSIZ on google or mail archives may turn it
> up - that's the kernel option but requires a recompile.

Ok, I am going to gradually try different limits. It seems as though setting
and so on in /boot/loader.conf will allow me to increase the limits.
Having to reboot is a pain, though. How far can I go? 512M? (Physical
memory is 1GB)

> Of course, limits may not be the issue at all.  They are a likely
> suspect given your error message, but maybe it's worth checking other
> bits of the mail system.  Can you email a file of the size your are
> trying not through mailman?  Maybe your MTA (sendmail/postfix etc) has a
> limit that somehow causes mailman to get this error.

This is definitely not the case. Users can receive (and send) similar
sized large attachments individually, so the MTA (sendmail in this case)
is not the cause.

> The final suggestion is to try to trace (ktrace, strace from ports) the
> process that is dying, but I suspect mailman forks a new process to deal
> with the email so how you catch it, I don't know.  Many demons have a
> "run in foreground without forking" option which can be helpful to
> debugging, but I don't know if anything like that is possible in
> mailman.  If you can figure out what mailman actually runs to process
> the email, you could ktrace that from the command line.  Maybe the
> mailman mailing list could give you an incantation to try.

I'll admit it is my first time to try a ktrace, but after noting which
process it was that crashed I could identify the newly spawned PID, and
obtained a ktrace.out (binary) and a kdump  (called
mailman_process_log.txt) when the problems occurs by sending another large
mail attachment.  I'll leave the files up for a couple of days. (Both
files are about 2MB in size)

Not that I can properly interpret the results, but it seems the mail file
is completely read, but whatever happens next causes the memory error.

 52506 python2.5 RET   read 354/0x162
 52506 python2.5 CALL  break(0x8add000)
 52506 python2.5 RET   break 0
 52506 python2.5 CALL  break(0x8cc3000)
 52506 python2.5 RET   break -1 errno 12 Cannot allocate memory

Thanks again for your time and suggestions.

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