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 the name of the module and the line number in it that is currently running.

Conventional debugging tools such as strace, pstack and gdb are not very useful for Python code. Most stack frames just contain functions from the interpreter code like PyEval_EvalFrameEx and and PyEval_EvalCodeEx, it doesn't give you any hint on were in the .py-file the execution is.

Answer 1

Some of the answers in Showing the stack trace from a running Python application are applicable in this situation:

• pyrasite (this was the one that worked for me):

  $ sudo pip install pyrasite
  $ echo 0 | sudo tee /proc/sys/kernel/yama/ptrace_scope
  $ sudo pyrasite 16262 dump_stacks.py # dumps stacks to stdout/stderr of the python program
  

• pyringe

• pydbattach - couldn't get this to work, but the repository https://github.com/albertz/pydbattach contains pointer to other tools
• pstack reportedly prints the python stack on Solaris