It gets run by the interpreter that mod_perl was compiled with. That's not the issue though. Apache::DProf dumps out a file for every apache child process. If you only send one request, then only one of them will record anything. That's why I suggested sending a few hundred requests with ab, so that every process will get some.
I have only got 5 child processes running, and i am looking at every single directory for each of them, and nothing. Just the headers.
So its not that i am missing the one client that is logging. Its just not working.
