Signals not forwarded to child processes

[jonashaag]

Checks

• I have checked that this issue has not already been reported.

• I have confirmed this bug exists on the latest version of pixi, using pixi --version.

Reproducible example

pixi run python sig.py
kill -INT <pixi run PID>
kill -INT <python PID>

Issue description

When you send a signal to the pixi parent process it's not forwarded to the child.

import signal
import time

def signal_handler(signum, frame):
    print(f"Signal handler called with signal {signum}")

signal.signal(signal.SIGINT, signal_handler)

while True:
    time.sleep(1)

Expected behavior

Should forward signals

[wolfv]

I did investigate this issue a bit and CTRL+C in the terminal works fine on macOS - and I think we would have heard about this more otherwise 🙂

What does indeed not work properly is to send a signal with kill to the pixi run process.

Sending the signal with kill to the child process of pixi works fine. Not sure how to properly fix this yet.

[stammler]

I have the same issue with signals not being forwarded to child processes in pixi run.

My use case is a SLURM job that is sending signals shortly before the timeout to let the program safely exit.

Here is a minimum working example:

The SLURM batch file looks as follows and sends SIGTERM 60 seconds before the timeout.

#!/bin/zsh
#SBATCH --job-name=test
#SBATCH .
#SBATCH .
#SBATCH .
#SBATCH --time=00:03:00
#SBATCH --signal=B:15@60
#SBATCH --output=job_%x_%j.out

export PYTHONUNBUFFERED=1
exec ~/.pixi/envs/default/bin/python test.py   # <--- works
exec pixi run python test.py                   # <--- does not work

This is the test.py file:

import signal
import time
import sys
import os

def handler(signum, frame):
    print(f"[{time.ctime()}] Received signal {signum}, saving state and exiting.")
    sys.stdout.flush()
    time.sleep(1)
    sys.exit(0)

signal.signal(signal.SIGTERM, handler)

print(f"PID: {os.getpid()}")
print(f"[{time.ctime()}] Simulation starting...")
sys.stdout.flush()

# Some long-running job
for i in range(300):
    print(f"Step {i}")
    sys.stdout.flush()
    time.sleep(1)

Are there any plans of forwarding signals to the child processes?