SIG32 with Linux and pthreads

[D. R. Evans]

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This is the kind of question that looks like it should be a FAQ, but a 
review of the archives didn't help find an answer :-( This probably means 
I'm doing something fundamentally wrong, I suppose

Running Mandrake 7.2, gdb 5.0. 

The big question is: am I supposed to be able to debug multi-threaded 
programs with the above system?

The archives sort-of indicate that I should be fine, but I am finding it to 
be impossible. A program that runs properly when merely executed is 
undebugable under gdb because I get a couple of SIG32 messages the first 
couple of times through a thread-creation loop, and then the program aborts 
the third time through :-(

Paring everything down I get to the following tiny program:

... header includes removed

void* dummy(void* vp)
{ cout << "Inside dummy" << endl;
}

void main(void)
for (int n = 0; n < 10; n++)
{ pthread_t d;
    
  const int status = pthread_create(&d, NULL, dummy, NULL);
  cout << "status: " << status << endl;
}

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When I execute this under GDB I see:

Starting program: /home/n7dr/test
warning: Unable to find dynamic linker breakpoint function.
GDB will be unable to debug shared library initializers
and track explicitly loaded dynamic code.

Program received signal SIG32, Real-time event 32.
0x400c017e in sigsuspend () from /lib/libc.so.6
(gdb) Inside dummy

Nothing else appears on the screen, and gdb seems to be waiting for input.
The executable seems to be stopped somewhere inside a signal handler.

How do I force the program to continue without stopping because of a signal 
every time I execute pthread_create()?

For reasons that I don't yet understand, the actual code (which of course 
is more complicated than the above) only gets a SIG32 the first two times 
through pthread_create(); the third time an ABORT signal is sent, so the 
program dies. The above program seems to generate the SIG32 only (i.e., it 
never generates an ABORT signal). But I figured that I'd start out with 
asking only the easier question. Then I'll move on to trying to figure out 
why the third time is different in the real code :-)

  Doc Evans

PS "info threads" produces no output. Ever.




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D.R. Evans N7DR / G4AMJ                      address@hidden

Two assassins and one very manipulative businessman: 
   "Reflexive Action" is now available. 
See http://www.sff.net/people/N7DR/drevans.htp for details.
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