Send signal (SIGINT) to a C sub-process [closed]

When using Python bindings to a C++ library that spawn processes, the SIGINT might not be received by all child processes. Instead, Python only processes SIGINT once execution returns to its scope.

To prevent this behavior, you may want to try process groups - setpgrp - set the process group ID.

For example:

1. Group all spawned processes together

2. Handle signals in Python

3. Forward the signal captured to the entire process group

Code example:

import os
import signal
import sys
from types import FrameType
from typing import NoReturn

# Set the current process in its own process group
os.setpgrp()


def signal_handler(signalnum: int, _: FrameType) -> NoReturn:
    # Ignore the captured signal number while handling it to prevent maximum recursion depth
    signal.signal(signalnum=signalnum, handler=signal.SIG_IGN)

    print(f"Received signal {signalnum}")

    # Send signal to all processes in the group
    os.killpg(0, signalnum)
    # Exit the execution
    sys.exit(1)


# Configure the signals you want to capture
# Capture SIGINT (Ctrl+C) and call `signal_handler` custom function
signal.signal(signalnum=signal.SIGINT, handler=signal_handler)

# Your code
...

I hope this helps!

You can use this style to send a sigint to a given PID. You should capture or search for the PID when creating the subprocess.

import os
import signal

def send_sigint(pid):
    try:
        os.kill(pid, signal.SIGINT)
        print(f"SIGINT signal sent to process {pid}")
    except ProcessLookupError:
        print(f"No process found with PID {pid}")
    except PermissionError:
        print(f"Permission denied to send SIGINT to process {pid}")

pid = 12345  # Replace with the actual PID
send_sigint(pid)

Or alternatively using subprocess

import subprocess
import signal

process = subprocess.Popen(..)
process.send_signal(signal.SIGINT)