Hanging process

I am writing a module for php, every so often an apache process will hang when it reaches MaxRequestsPerChild. It grabs all available cpu time, yet server-status reports no additional usage. I have removed the PHP_MSHUTDOWN function from my code in case I was making a hash out of something inadvertently, yet this has not helped. It is only occurring 1 in 20 times (approximately) apache tries to close a process. I am new to development on Linux and do not know all the tools available, is there some way that I can find out what this process is doing or at least if the loop is in apache, php or my code so I can trace it back? Thanks, Bill