Debug python process with GDB

bash-4.1# gdb python
GNU gdb (GDB) Red Hat Enterprise Linux (7.2-75.el6)
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Reading symbols from /usr/bin/python...Reading symbols from /usr/lib/debug/usr/bin/python2.6.debug...done.
done.
(gdb) attach 12168
Attaching to program: /usr/bin/python, process 12168
Reading symbols from /usr/lib/libpython2.6.so.1.0...Reading symbols from /usr/lib/debug/usr/lib/libpython2.6.so.1.0.debug...done.
done.
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(gdb) info threads
  3 Thread 0xb7574b70 (LWP 12171)  0x00b3f424 in __kernel_vsyscall ()
* 2 Thread 0xb69ffb70 (LWP 23478)  0x00e15c82 in PyEval_EvalFrameEx (f=
    Frame 0xb5e01424, for file /home/iupui_npad/build/DiagServer.py, line 341, in handle (self=<DiagRequestHandler(wfile=<_fileobject at remote 0x81790ec>, request=<_socketobject at remote 0x8175e64>, server=<DiagServer(RequestHandlerClass=<classobj at remote 0x817b0ec>, server_address=('::', 8001, 0, 0), _BaseServer__shutdown_request=False, _BaseServer__is_shut_down=<_Event(_Verbose__verbose=False, _Event__flag=False, _Event__cond=<_Condition(_Verbose__verbose=False, _Condition__lock=<thread.lock at remote 0xb770d360>, acquire=<built-in method acquire of thread.lock object at remote 0xb770d360>, _Condition__waiters=[], release=<built-in method release of thread.lock object at remote 0xb770d360>) at remote 0x817aa6c>) at remote 0x817aa8c>, socket=<_socketobject at remote 0x8175e2c>) at remote 0x817aaac>, connection=<...>, rfile=<_fileobject at remote 0x81795ec>, client_address=('::ffff:113.240.250.155', 64839, 0, 0)) at remote 0x817adcc>, xargs=[], handshake=False, line='\r\n', cmd=[]), throwflag=0) at Python/ceval.c:2156
  1 Thread 0xb771c6c0 (LWP 12168)  0x00b3f424 in __kernel_vsyscall ()

(gdb) thread apply all py-list

Thread 3 (Thread 0xb7574b70 (LWP 12171)):
 386    
 387    
 388    # Kill off misbehaving tests
 389    def watchdog(serv):
 390            while True:
>391                    time.sleep(WATCHDOG_TIME/5)
 392                    serv.test_list_cv.acquire()
 393                    try:
 394                            if len(serv.test_list) > 0:
 395                                    test = serv.test_list[0]
 396                                    if test.kill_test !=  None and time.time() - test.test_start_time > WATCHDOG_TIME:

Thread 2 (Thread 0xb69ffb70 (LWP 23478)):
 336                    xargs=[]
 337                    try:
 338                            stats.requests += 1
 339                            handshake = False
 340                            line = self.rfile.readline()
>341                            while line != "":
 342                                    cmd = line.split()
 343                                    if len(cmd) < 1:
 344                                            continue
 345    
 346                                    if not handshake:

Thread 1 (Thread 0xb771c6c0 (LWP 12168)):
 150    
 151    def _eintr_retry(func, *args):
 152        """restart a system call interrupted by EINTR"""
 153        while True:
 154            try:
>155                return func(*args)
 156            except (OSError, select.error) as e:
 157                if e.args[0] != errno.EINTR:
 158                    raise
 159    
 160    class BaseServer:
(gdb) thread 2
[Switching to thread 2 (Thread 0xb69ffb70 (LWP 23478))]#0  0x00e15c82 in PyEval_EvalFrameEx (f=
    Frame 0xb5e01424, for file /home/iupui_npad/build/DiagServer.py, line 341, in handle (self=<DiagRequestHandler(wfile=<_fileobject at remote 0x81790ec>, request=<_socketobject at remote 0x8175e64>, server=<DiagServer(RequestHandlerClass=<classobj at remote 0x817b0ec>, server_address=('::', 8001, 0, 0), _BaseServer__shutdown_request=False, _BaseServer__is_shut_down=<_Event(_Verbose__verbose=False, _Event__flag=False, _Event__cond=<_Condition(_Verbose__verbose=False, _Condition__lock=<thread.lock at remote 0xb770d360>, acquire=<built-in method acquire of thread.lock object at remote 0xb770d360>, _Condition__waiters=[], release=<built-in method release of thread.lock object at remote 0xb770d360>) at remote 0x817aa6c>) at remote 0x817aa8c>, socket=<_socketobject at remote 0x8175e2c>) at remote 0x817aaac>, connection=<...>, rfile=<_fileobject at remote 0x81795ec>, client_address=('::ffff:113.240.250.155', 64839, 0, 0)) at remote 0x817adcc>, xargs=[], handshake=False, line='\r\n', cmd=[]), throwflag=0) at Python/ceval.c:2156
2156                Py_DECREF(v);
(gdb) py-bt
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(gdb) py-locals
self = <DiagRequestHandler(wfile=<_fileobject at remote 0x81790ec>, request=<_socketobject at remote 0x8175e64>, server=<DiagServer(RequestHandlerClass=<classobj at remote 0x817b0ec>, server_address=('::', 8001, 0, 0), _BaseServer__shutdown_request=False, _BaseServer__is_shut_down=<_Event(_Verbose__verbose=False, _Event__flag=False, _Event__cond=<_Condition(_Verbose__verbose=False, _Condition__lock=<thread.lock at remote 0xb770d360>, acquire=<built-in method acquire of thread.lock object at remote 0xb770d360>, _Condition__waiters=[], release=<built-in method release of thread.lock object at remote 0xb770d360>) at remote 0x817aa6c>) at remote 0x817aa8c>, socket=<_socketobject at remote 0x8175e2c>) at remote 0x817aaac>, connection=<...>, rfile=<_fileobject at remote 0x81795ec>, client_address=('::ffff:113.240.250.155', 64839, 0, 0)) at remote 0x817adcc>
xargs = []
handshake = False
line = '\r\n'
cmd = []
(gdb)