problem with core dumps and multi-threaded daemon

From	Gorlash <dan.miller.x23@gmail.com>
Newsgroups	comp.os.linux.development.system
Subject	problem with core dumps and multi-threaded daemon
Date	2011-07-18 11:49 -0700
Organization	http://groups.google.com
Message-ID	<64909bbc-5fb3-4ceb-9bba-2b75eec6b158@h7g2000prf.googlegroups.com> (permalink)

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I'm using Ubuntu server 10.10 (2.6.35-22-generic-pae)
I have a daemon running on my system, and it processes tcp packets and
other data sources, using multiple pthreads.  I'm finding that every
once in awhile it generates a segfault, and I'm trying to get some
clues as to what is going wrong.  All I get in /var/log/messages is:
Jul 18 11:15:32 u10hub kernel: [ 8688.898805] grunion[11319]: segfault
at b77ea000 ip 00688fb6 sp b77e7b18 error 6 in
libc-2.12.1.so[613000+157000]

I've added SIGSEGV to the list of signals that I monitor, but it does
not appear to to get invoked (though it *does* get invoked if I send
'sudo killall -11 grunion').

I tried getting it to generate a coredump by setting 'ulimit -c
unlimited', and 'ulimit -a' shows that being set as requested, but
when it segfaulted most recently, there was no core file that I could
find.

I have a couple of questions:
> why didn't segfault generate SIGSEGV to the application?  Do I have to call sigaddset() and kin, seperately in each thread??
> with a daemon, which doesn't really have a home directory, where would the core file get generated?  Do I somewhere need to explicitly set the 'home' directory?

tia
Dan Miller

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problem with core dumps and multi-threaded daemon Gorlash <dan.miller.x23@gmail.com> - 2011-07-18 11:49 -0700
  Re: problem with core dumps and multi-threaded daemon Rainer Weikusat <rweikusat@mssgmbh.com> - 2011-07-18 19:54 +0100
    Re: problem with core dumps and multi-threaded daemon Gorlash <dan.miller.x23@gmail.com> - 2011-07-18 12:03 -0700
      Re: problem with core dumps and multi-threaded daemon Jorgen Grahn <grahn+nntp@snipabacken.se> - 2011-07-18 20:52 +0000
  Re: problem with core dumps and multi-threaded daemon Jorgen Grahn <grahn+nntp@snipabacken.se> - 2011-07-18 21:08 +0000
    Re: problem with core dumps and multi-threaded daemon Gorlash <dan.miller.x23@gmail.com> - 2011-07-18 14:33 -0700
      Re: problem with core dumps and multi-threaded daemon Jorgen Grahn <grahn+nntp@snipabacken.se> - 2011-07-18 22:34 +0000
        Re: problem with core dumps and multi-threaded daemon Gorlash <dan.miller.x23@gmail.com> - 2011-07-18 17:51 -0700

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