gdb backtrace and pthread_cond_wait()

Question

This is on a Redhat EL5 machine w/ a 2.6.18-164.2.1.el5 x86_64 kernel using gcc 4.1.2 and gdb 7.0. When I run my application with gdb and break in while it's running, several of my threads show the following call stack when I do a backtrace: ``` #0 0x000000000051d7da in pthread_cond_wait () #1 0x0000000100000000 in ?? () #2 0x0000000000c1c3b0 in ?? () #3 0x0000000000c1c448 in ?? () #4 0x00000000000007dd in ?? () #5 0x000000000051d630 in ?? () #6 0x00007fffffffdc90 in ?? () #7 0x000000003b1ae84b in ?? () #8 0x00007fffffffdd50 in ?? () #9 0x0000000000000000 in ?? () ``` Is this a symptom of a common problem? Is there a known issue with viewing the call stack while waiting on a condition?

Accepted Answer

The problem is that `pthread_cond_wait` is written in hand-coded assembly, and apparently doesn't have proper unwind descriptor (required on x86_64 to unwind the stack) in your build of `glibc`. This problem may have recently been fixed here.

You can try to build and install the latest glibc (note: if you screw up installation, your machine will likely become unbootable; approach with extreme caution!), or just live with "bogus" stack traces from `pthread_cond_wait`.

gdb backtrace and pthread_cond_wait()

Solution

Problem