[iiwusynth-devel] Re: [Swami-devel] iiwusynth segfault

[Josh Green]

On Wed, 2003-01-22 at 10:40, Mark Knecht wrote:
> > 
> > > gdb iiwusynth
> > 
> > (gdb) set args -a jack
> > (gdb) r
> > 
> > wait for segfault
> > 
> 
> OK, unless it takes a really long time to get the segfault, I waited
> about 10 minutes and it didn't happen. I did get this interesting
> message:
> 
> address@hidden mark]$ gdb iiwusynth
> GNU gdb Red Hat Linux (5.2-2)
> Copyright 2002 Free Software Foundation, Inc.
> GDB is free software, covered by the GNU General Public License, and you
> are
> welcome to change it and/or distribute copies of it under certain
> conditions.
> Type "show copying" to see the conditions.
> There is absolutely no warranty for GDB.  Type "show warranty" for
> details.
> This GDB was configured as "i386-redhat-linux"...
> (gdb) set args -a jack
> (gdb) r
> Starting program: /usr/local/bin/iiwusynth -a jack
> [New Thread 1024 (LWP 7323)]
> iiwusynth: debug: Using 'jack' audio driver
> 
> iiwusynth: debug: Jack engine sample rate: 44100
> 
> [New Thread 2049 (LWP 7324)]
> Can't attach LWP 7324: Operation not permitted
> (gdb)
> 
> 

Okay, ignoring the "Can't attach LWP.." message I think probably what is
happening is there is a real time SIG32 that gets trapped by gdb
sometimes for multi-threaded programs, so it is stopping before it
segfaults. Enter this (before running the program, with "r") to ignore
them:

(gdb) handle SIG32 nostop noprint pass

If for some reason it still stops before segfaulting (you'll get a
message that lets you know) you can enter "c" to continue running it. Do
so until it crashes. Then, run the backtrace :) That should work, but..

If for some reason you aren't able to get things to work in gdb, you
could always enable core dumping, run iiwusynth which will dump a core
file, then run gdb on the core file.

bash prompt> ulimit -c 16384

Which will set a 16MB max core size (its set to 0 on many systems to
stop cores from being dumped all over the place).

Then:

prompt> gdb iiwusynth core

(gdb) bt

That would work as well.

> 
> I hope this is helpful!
> 
> Cheers,
> Mark

Not quite yet :) Need to get the right back trace of the crash. Cheers.
        Josh Green

P.S. Something else to make sure of is that you don't have any old
versions of libiiwusynth.so.* hanging around. This can cause lots of
weired problems.