Question about signals in apptainer

[Wentao Lu]

Hello! I have a quick and maybe dumb question about signals in apptainer. How does apptainer intercept and handle signals?

Let's say I first enter the container and run a Python script

```

apptainer exec mycontainer.sif /usr/bin/python3 myPyScript.py

```

and then the Python script sets up my custom environment and launches my main program using `subprocess.Popen()`.

When my main program receives a crash signal such as SIGSEGV, is apptainer going to kill it? does it do something special? or maybe it depends? when would apptainer send signals to a child process?

I've noticed that sometimes when my main program crashed hard, it brought down the entire apptainer. I also have a signal handler in my main program, but it wasn't always able to catch the signal in some cases after moving into the container. I don't think apptainer is doing wrong, but just want to understand how it handles signals and maybe get some hints.

Thanks!

[Dave Dykstra]

Hi Wentao,

In the case of your program getting a SIGSEGV, apptainer won't be involved in handling it all. The operating system will send that signal directly to your program.

apptainer does manage a few signals such as SIGINT and SIGTERM, but it does nothing with SIGSEGV.

Dave

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