Question About No Output From strace

The quick solution is to use MaxRequestsPerChild (number) (for example, 10000) to have the Apache restart each worker after that many requests. That will discard the memory used when it's restarted.

The 276m number isn't how much each process is using though. An explanation of the values shown in 'top' is helpful here:

VIRT: Virtual Image (kb) The total amount of virtual memory used by the task. It includes all code, data and shared libraries plus pages that have been swapped out. (if you are using APC, the memory space used by it will also be included in this value)

RES: Resident size (kb) The non-swapped physical memory a task has used.

SHR: Shared Mem size (kb) The amount of shared memory used by a task. It simply reflects memory that could be potentially shared with other processes.

In 'top', you can add a 'data' column Data: Data+Stack size (kb) The amount of physical memory devoted to other than executable code, also known as the ’data resident set’ size or DRS.

That 'Data' value more closely matches the unique memory being used by that particular process, which is probably not that much. Adding up those 276M and getting a number near to 2GB means that you're double-counting a lot of things.

The child processes should stop as soon as they finish handling their current requests. Do you really want your server drop connections in the middle of serving a page? The restarted server will handle all new connections, as it has taken over listening for new connections.

Check after a minute or so to ensure that the children of the old server have died. If they are still running then you likely have a problem.