apache_child_terminate when called by a script running under apache's mod_php will cause the current process serving the request and executing the script to terminate once the request is complete.

This is useful if a script "knows" it has allocated a large ammount of memory (which apache can't possibly give back to the system) and is likely to be invoked again by another apache process soon leaving the system with all apache processes hogging large ammounts of memory which they are never likely to need again unless they get lucky and the same greedy script gets assigned to one of it's previous processes.

Previously the fix was to set all apache processes to terminate after serving only one request but now the greedy script can just call apache_child_terminate(); instead - which actually has the effect of making it look like that apache process has served past it's limit.