I've occasionally run up against a server's memory allocation limit, particularly with a bloated application like Wordpress, but never encountered "Unable to allocate memory for pool" and having trouble tracking down any information.

Does anyone know what this means? Have tried increasing the memory_limit without success. Also haven't made any significant changes to the application -- just one day no problem, next day error messages.

Is it possible this is a caching issue?

Accepted Answer

Probably is APC related.

For the people having this problem, please specify you .ini settings. Specifically your apc.mmap_file_mask setting.

For file-backed mmap, it should be set to something like:


To mmap directly from /dev/zero, use:


For POSIX-compliant shared-memory-backed mmap, use:


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