Considering segfaults: how to protect other requests?

Hi there... Hopefully I've chosen a good place to start with a problem like this: using apache2 prefork, I've confirmed that the same PHP extension can receive multiple requests through browser and if one of those requests causes a segfault, the other request, which is still in process during the segfault, will be completed. Good... But how to be sure if this is just a particular case or there is some way to know that ONLY those requests will get terminated, which are themselves causing a segfault? Or make it that way? What should I read to understand (sufficiently well) what is going on inside of Apache and PHP to be sure of questions like this? I know short is in a conflict with complete or even sufficient, but anyway... Have to get started. Your advices are welcome!