How can I debug a Python SIGCHLD handler?

Question

I'm writing a server program in Python that uses the following workflow: 1) Start a daemon 2) Start a server socket and listen for incoming connections 3) When an incoming socket is accepted successfully, fork a new process to handle the connection, closing the client socket in the child and the server socket in the daemon.

When I register a signal handler for SIGCHLD in the daemon process to reap child processes (regardless of the content of the handler) and run the server, the daemon crashes when it receives SIGCHLD. I can't for the life of me figure out why because for whatever reason logging to syslog won't work for me, and I have no way of debugging this. I'm using PyCharm and it has no way to debug forked processes. How can I debug this problem ? What could be causing the program to fail on invocation of the SIGCHLD handler ?

I'm using Python 3.4 on Mac OS X.8

Answer 1

As it turns out, I was using an incorrect signature for my signal handling function. I was using def my_handler() instead of def my_handler(signum, frame) , as per this thread