Infinite loop bug in libc_r on 4.x with condition variables and signals

[John Birrell]

On Thu, Oct 28, 2004 at 03:54:07PM -0400, John Baldwin wrote:
> We've started testing on -current and are seeing several problems with 
> libpthread.  Using a UP kernel (machines have single processor with HTT) 
> seems to make it better, but we seem to be getting SIG 11's in 
> pthread_testcancel() as well as the failed lock assertions that were 
> mentioned earlier on the list in the PR.  Just running monodevelop from the 
> bsd-sharp stuff mentioned earlier can break in that one of the processes dies 
> with the assertion failure.  If you let the other processes run, then you can 
> run it again and get the window to pop up, but then clicking on any of the 
> controls results in the pthread_testcancel() crash.  FWIW, I think the reason 
> that the stack traces look weird in the PR's thread may be due to catching a 
> signal.  When we were looking at the problems with libc_r on 4.x we would get 
> some weird looking backtraces sometimes when the assertion in uthread_sig.c 
> that I added failed.  Seems that gdb doesn't handle the signal frames very 
> well.

I have a server running -current as of July 23 which runs a process that often
SIG 11's in pthread_testcancel() too. I've never been able to make sense of the
back trace because it always shows the initialisation path for a module, yet
for the process to run and serve web requests, that initialisation path must
have been completed. I've assumed there is a bug in my code elsewhere in the
application and that GDB is telling me the truth.

-- 
John Birrell