With apache 2.3.15 I had kinda the same issue with mod_fcgidon ubuntu 8.04 as on windows. With -k restart or -k graceful the server did not die like on windows, but the server delivered than only a 200 OK response header, but nothing more. Switching from worker mpm to event mpm seemed to solve this, but the server died later :-/
Since it has talmost the same issues like on windows I could make a patch that fixes this. Grab the patch (patched against trunk) for the patch for 2.3.6
The bug 50309 is now longer than a year listet. Bad that none applied it yet.
I made some testing on my dev machine and liked event mpm. So I installed it here. I noticed that the event mpm closes the connections faster than worker mpm. Some download tests sadisfied me. Less memory usage and faster serving :-) For now I keeped the settings from worker mpm. I’ll look for tweaking in the next days.
Different to the docs event mpm works fine with SSL.
sudo apt-get install apache2-mpm-event libapache2-mod-fcgid
Also the serving PHP over fcgid is nice. The implementation of PHP over fcgid in the older post.