If you have run into defunct php processes that keep running on the server which causes the CPU load to increase, read on…
Normally to kill these process we can use
but this is not a permanent solution.
The root cause of this issue is usually due to an apache bug related to the suphp module.
According to http://www.suphp.org/FAQ.html:
When I am using suPHP I have zombie processes. What’s the problem?
Apache 1.3.28 has a bug in the Apache core which causes CGI processes not to be ended correctly. mod_suphp uses some of this core functions, however it is not a bug in mod_suphp but in Apache itself. The bug is first occured in Apache 1.3.28 and is fixed since Apache 1.3.29