How do I do logging in a WSGI application across several processes?
Direct logging output to sys.stderr. Doing that will see anything logged get routed into the internal Apache logging routines and into the Apache error logs. The way Apache does this works when done from multiple process at the same time.
I have a simple webservice written in Python WSGI, it's running in Apache and modwsgi using the WSGIDaemonProcess processes=4 directive. 
How do I add logging? Obviously I can't log to the same file without some sort of mutex, but I don't want performance degraded.
The logging can't block. As far as I know the standard logging module blocks on every log call.
I was thinking of doing some sort of socket logging, is this viable? Would it require a "server" process to receive logging? What happens if the server isn't on?