debugging multithreaded applications

debugging multithreaded applications

[my Name]

Hello,

I'm trying to debug multithreaded applications. But I
think I am doing something wrong. I'm using RedHat
Fedora Core 2, gcc 3.3.3, gdb 6.3 (built from source).
I created a simple program spawning a thread which
prints to cout, while the "main" thread just calls
pthread_join on the working one. 

#include <iostream>
#include <pthread.h>
#include <time.h>

using namespace std;

bool g_shouldrun = true;

void* work(void*){
    while (g_shouldrun) 
    {
        timespec t = {1,0};
        timespec remaining = t;
        //while ((remaining.tv_sec +
remaining.tv_nsec) != 0) 
        {
            nanosleep(&t,&remaining);
        }
        std::cout << "hello world" << std::endl;
//line 18
    }
	std::cout << "ok, enough of it" << std::endl;
}

int main (int argc, char *argv[])
{
    cout << "hello main" << endl;
    pthread_t thread;
    int a = pthread_create(&thread,0,&work,0);
    pthread_join(thread,0);
    return(0);
}



If I enter breakpoints into work (line 18), the
program is stopped if I use gdb (version 6.3). If
using gdbserver, after starting the process I get
"Cannot find new threads: capability not available",
and later the child process is terminated with "signal
= 5", SIGTRAP
Since I did not find anything in the manual that said
whether or not gdbserver can be used with
multithreaded programs, I hope someone on this mailing
list can help.
Is it possible to debug multithreaded programs using
gdbserver and if so, how?

Regards,
Thomas Fenzl


		
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Re: debugging multithreaded applications

[Daniel Jacobowitz]

On Tue, Aug 16, 2005 at 08:24:22AM -0700, my Name wrote:
> If I enter breakpoints into work (line 18), the
> program is stopped if I use gdb (version 6.3). If
> using gdbserver, after starting the process I get
> "Cannot find new threads: capability not available",
> and later the child process is terminated with "signal
> = 5", SIGTRAP
> Since I did not find anything in the manual that said
> whether or not gdbserver can be used with
> multithreaded programs, I hope someone on this mailing
> list can help.
> Is it possible to debug multithreaded programs using
> gdbserver and if so, how?

You shouldn't need to do anything special if they're on the same system
as your gdb.  If you're trying to debug on another system, search for
solib-absolute-prefix.

You may also want to give the CVS version a try.

-- 
Daniel Jacobowitz
CodeSourcery, LLC