Check what a running process is doing: print stack trace of an uninstrumented Python program

Question

Is there a way on Linux to check what a running Python daemon process is doing? That is, without instrumenting the code and without terminating it? Preferably I\'d like to get t

Answer 1

lptrace does exactly that. It allows you to attach to a running Python process and show currently executing functions, like strace does for system calls. You can call it like this:

vagrant@precise32:/vagrant$ sudo python lptrace -p $YOUR_PID
fileno (/usr/lib/python2.7/SocketServer.py:438)
meth (/usr/lib/python2.7/socket.py:223)

fileno (/usr/lib/python2.7/SocketServer.py:438)
meth (/usr/lib/python2.7/socket.py:223)
...

Note that it requires gdb to run, which isn't available on every server machine.