Suprocesses are not properly cleaned up

[thetheodor]

We need to send death signals to subprocesses (e.g., creduce's sigterm)

[thetheodor]

import os
import signal

os.setpgrp()

def cleanup(signum, frame):
    os.killpg(0, signal.SIGKILL)```

[thetheodor]

chatgpt suggests:

You can set subprocess.Popen parameter start_new_session=False and attach a signal handler to the parent process to forward signals like SIGTERM and SIGINT to the child processes.

Example:

import subprocess
import signal
import os

def signal_handler(signum, frame):
    for p in child_processes:
        p.send_signal(signum)

signal.signal(signal.SIGTERM, signal_handler)
signal.signal(signal.SIGINT, signal_handler)

child_processes = []

# Launch subprocess
p = subprocess.Popen(["your_command"], start_new_session=False)
child_processes.append(p)

# Your main program logic here

This ensures that when the parent receives SIGTERM or SIGINT, it forwards the signal to the child processes for cleanup.

diopter.Reducer 
 |
 | - python.subprocesss[creduce]   <--- creduce kills its subprocesses
         |
         |- creduce.subprocess1
         |  |
         |  |- python.reducer_callback
         |       |
         |       |-> python.subprocess[gcc/whatever]  <--------- the signal must be propagated here
         |
         |- creduce.subprocess2
         |- ...
         |- creduce.subprocessn

[thetheodor]

@shao-hua-li is this still a problem for you?

[shao-hua-li]

Sometime yes, but is already rare for me.