Using Pydev with embedded sub-interpreters - Crash at Py_EndInterpreter()

car-bianco commented 1 year ago

Hello everyone!

I have been tasked with integrating debugging via Pydev into an application consisting of multiple Python scripts being executed within a C++ process. Every script runs in its own Python interpreter instance. I am using PyDev 9.3.0 on Linux.

When the process enters a certain "shutdown" phase, all interpreters should be terminated by calling Py_EndInterpreter(). When Pydev is enabled, the process is aborted with the following error traceback:

Fatal Python error: Py_EndInterpreter: not the last thread
Python runtime state: initialized

Thread [...] (most recent call first):
  File "[...]/pysrc/pydevd.py", line 2250 in __wait_for_threads_to_finish
  File "[...]/pysrc/pydevd.py", line 2315 in dispose_and_kill_all_pydevd_threads
  File "[...]/pysrc/pydevd.py", line 1768 in process_internal_commands
  File "[...]/pysrc/pydevd.py", line 210 in _on_run
  File "[...]/pysrc/_pydevd_bundle/pydevd_daemon_thread.py", line 49 in run
  File "[...]/python3/lib/python3.10/threading.py", line 1009 in _bootstrap_inner
  File "[...]/python3/lib/python3.10/threading.py", line 966 in _bootstrap

Thread [...] (most recent call first):
  File "[...]/pysrc/_pydevd_bundle/pydevd_comm.py", line 219 in _read_line
  File "[...]/pysrc/_pydevd_bundle/pydevd_comm.py", line 238 in _on_run
  File "[...]/pysrc/_pydevd_bundle/pydevd_daemon_thread.py", line 49 in run
  File "[...]/python3/lib/python3.10/threading.py", line 1009 in _bootstrap_inner
  File "[...]/python3/lib/python3.10/threading.py", line 966 in _bootstrap

Though dispose_and_kill_all_pydevd_threads() is being executed, it looks like the ReaderThread and the PyDBCommandThread are not being closed. They are daemon threads - so they are only ended when the program exits.

Are there any workarounds in order to "gracefully shutdown" those threads anyway, or suggestions as to how this issue can be solved?

fabioz commented 1 year ago

If you execute only in pure-python mode, does this still happen?

i.e.: if you set an environment variable as: PYDEVD_USE_CYTHON=NO

car-bianco commented 1 year ago

If you execute only in pure-python mode, does this still happen?

i.e.: if you set an environment variable as: PYDEVD_USE_CYTHON=NO

This does not seem to make any difference, sadly.

Any suggestion as to what else we should try?

car-bianco commented 1 year ago

Hey @fabioz , Sorry for the double-reply.

After the following two steps, it looks like I can terminate the program successfully.

Calling pydevd.stoptrace() at the beginning of the "shutdown" phase
Restoring the commented-out code in https://github.com/fabioz/PyDev.Debugger/blob/26864816cbfcf002a99913bcc31ebef48042a4ac/_pydevd_bundle/pydevd_comm.py#L164-L171 and reverting the while True: to while not _kill_received:

Would you consider this to be a viable solution? If so, I'd find it reasonable to add the option to explicitly shutdown the reader thread.

fabioz / PyDev.Debugger

Using Pydev with embedded sub-interpreters - Crash at Py_EndInterpreter() #259