FastCGI applications are designed to run persistently, some FastCGI applications exit intentionally after a certain amount of time has passed or after they have served a certain number of requests to minimize the impact of any memory leaks. When FastCGI applications exit (or crash) the FastCGI process manager will detect this (by receiving a CHLD signal), perform some housekeeping and launch a new process.
When an Apache web server is configured to use the v18.104.22.1682 webagent it appears to be setting the signal mask of the main Apache process, and hence, the child FastCGI process manager process so that the process blocks CHLD signals.
Issue fix with 12.51CR04 Webagent.
From release 12.51CR04 note :
55892, 79811 If the Web Agent is configured, the Apache's FastCGI modules goes in to the zombie/defunct state.