Fong Vang wrote: > (or why the system does not release the semaphore if Apache > is no longer running). Because IPC resources (semaphores, message queues and shared memory segments) are not tied to a process, an process simply has access to them (and can request for resource to be created or destroyed). It is perfectly OK for a process to create any IPC resource, exit, and then some other process started at a later time to pick it up. If something is allocating IPC resources and not cleaning up behind itself, than it is a bug in application (where application != process). IPCs are outside of that nice box called process, so you should think outside of the box too.