[maemo-developers] [maemo-developers] Problem with GDB and threads...

[From: Christian Henz]

Hi.

I have a problem when trying to debug a multi-threaded application on the 
Nokia 770 (OS 2006).

This is my test program:
------------------------
#include <unistd.h>
#include <cassert>
#include <pthread.h>

void* routine( void* arg ) {

  while( 1 ) { }

  return 0;
}

int main( int argc, char** argv ) {

  pthread_t handle;

  int err = pthread_create( &handle, 0, routine, 0 );
  assert( err == 0 );

  sleep( 60 );

  return 0;
}
------------------------

On the PC, I do the following in gdb:

(gdb) inf thr
  2 Thread -1479910480 (LWP 29458)  routine (arg=0x0) at test.cpp:8
* 1 Thread -1479907648 (LWP 29455)  0xa7d3a2bc in nanosleep () 
from /lib/tls/libc.so.6
(gdb) thread apply all bt

Thread 2 (Thread -1479910480 (LWP 29458)):
#0  routine (arg=0x0) at test.cpp:8
#1  0xa7ef7ced in start_thread () from /lib/tls/libpthread.so.0
#2  0xa7d79dee in clone () from /lib/tls/libc.so.6

Thread 1 (Thread -1479907648 (LWP 29455)):
#0  0xa7d3a2bc in nanosleep () from /lib/tls/libc.so.6
#1  0xa7d3a0c4 in sleep () from /lib/tls/libc.so.6
#2  0x08048562 in main (argc=1, argv=0xafa2c274) at test.cpp:22


On the Nokia 770, the backtrace goes on forever and i have to kill
gdb:

(gdb) inf thr
  3 Thread 16386 (LWP 2269)  0x000084b0 in routine ()
  2 Thread 32769 (LWP 2268)  0x402a3474 in poll () from /lib/libc.so.6
* 1 Thread 16384 (LWP 2265)  0x4027e37c in nanosleep () from /lib/libc.so.6
(gdb) thread apply all bt

Thread 3 (Thread 16386 (LWP 2269)):
#0  0x000084b0 in routine ()
#1  0x40024a20 in pthread_start_thread () from /lib/libpthread.so.0
#2  0x40024a20 in pthread_start_thread () from /lib/libpthread.so.0
#3  0x40024a20 in pthread_start_thread () from /lib/libpthread.so.0
#4  0x40024a20 in pthread_start_thread () from /lib/libpthread.so.0
#5  0x40024a20 in pthread_start_thread () from /lib/libpthread.so.0
#6  0x40024a20 in pthread_start_thread () from /lib/libpthread.so.0
[...]

Has anyone else experienced this? Also, why is there an extra thread?

thanks,
Christian Henz