Debugging memory leaks in IHS

Known issue to check for

What to look for

If a growth of both RSS and VSZ can be demonstrated, it's important to verify that the memory usage never flattens out after many tens of thousands of hits. Any report of a memory leak must show both RSS and VSZ, for a fixed set of processes, over time.

Short term relief

Identifying a culprit

The following steps are required to help suppport identify the cause of a memory leak. When opening a PMR, be sure to illustrate which (if any) of the diagnostic steps have been taken and their impact on the symptom.

mod_memuse

mod_memuse is an Apache module that logs the high water mark of memory usage at each distinct phase of Apache processing. When the configuration has been limited to the smallest set of usable modules that still leak, mod_memuse may be able to further illustrate in which phase of Apache processing new memory is allocated. Most modules only operate in a few phases.

mod_memuse is available only from IBM HTTP Server L3 support.