How do I tell if apache is running (or configured to run) as prefork or worker?
The MPM is configured at compile time. One way to figure it out afterwards is to list compiled in modules. That list will include the chosen MPM. The listing can be accomplished running the apache binary, with the -l flag.
Here we find the module worker.c, hence I'm running the worker MPM.
On RHEL/Fedora/etc, run
Here 'Server MPM' is 'Prefork', so my server is running the prefork MPM.
The answers given by Series8217 and Andol are both incorrect.
The question was, how to tell if Apache is running prefork or worker. The advice given only tells what the default MPM is (based on compiled-in modules), not if that default or another choice is being used.
Which MPM is running can be shown using this process:
There are answers on several web sites saying, use httpd -V to tell if Apache is running prefork or worker. They are all wrong. Try the above procedure to see for yourself.