Re: [Libunwind-devel] Urgent - Help - 64 bit google profiler crashes (libunwind)

[Arun Sharma]

On 2/19/07, Jan Kratochvil <address@hidden> wrote:
> Hi,
>
> On Mon, 19 Feb 2007 13:03:56 +0100, Rajesh Balamohan wrote:
> ...
> > x86_64 x86_64 x86_64 GNU/Linux
> >
> > gdb) bt
> > #0  0x00002ba09f7fdf4f in _Unwind_FindEnclosingFunction () from 
> /lib64/libgcc_s.so.1
>
> This unwinder is a part of libgcc contained in the GCC package.
> It is unrelated to this libunwind project where you posted the mail.
> libunwind is currently in use for libgcc only on the platform ia64.

Using the libgcc unwinder will cause deadlocks when used with the
google profiler, because of the interaction with tcmalloc.
Specifically, the libgcc unwinder calls malloc() in some code paths
and tcmalloc (the google implementation of malloc included) calls the
unwinder. There is a gcc bugzilla with the details.

For this reason, I'd strongly suggest using libunwind. If it's
installed on your system, autoconf will detect it and use it.
Unfortunately, there is no released version of libunwind that works
well with the google profiler. You'll have to use a recent git
snapshot.

-Arun