Re: gdb does not show full backtrace for deadlocked pthread program.

[Ben Greear <greearb at candelatech dot com>]

Daniel Jacobowitz wrote:
> On Mon, Sep 26, 2005 at 12:24:06AM -0700, Ben Greear wrote:
>
> > Hello!
> >
> > I have a program that uses pthreads and evidently has a
> > nifty little thread deadlock.
> >
> > The interesting thing is that gdb will not show me the full
> > backtrace of the deadlocked threads.  Both tested system's running
> > a slightly modified 2.6.11 kernel.  The FC2 system is a dual-xeon with
> > SMP kernel.  The FC4 machine is a laptop with UP kernel.
> > FC2's gdb doesn't even decode frame 3, but on FC4 I get this:
> >
> > [after attaching to deadlocked process]
> >
> > (gdb) thread apply all bt
> >
> > Thread 2 (Thread -1208132688 (LWP 9895)):
> > #0  0xffffe410 in ?? ()
> > #1  0xb7fd50e8 in ?? ()
> > #2  0x00000002 in ?? ()
> > #3  0x004b4e7e in __lll_mutex_lock_wait () from /lib/libpthread.so.0
>
>
> GDB knows how to load symbols for the kernel DSO and backtrace from it. 
> It also knows how to load separate debug info packages, which I assume
> Red Hat provides for libc.  I would have expected the shipped GDB to do
> this, but if not, try building your own from current CVS.  If you
> install the debug info packages and want to use them, you may need to
> configure your own gdb with --prefix=/usr.

The latest cvs did indeed print out useful stack traces.  Would
be lovely to have whatever magic makes that work in the more
official releases!

Thanks,
Ben

>


--
Ben Greear <greearb@candelatech.com>
Candela Technologies Inc  http://www.candelatech.com