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From Stefan Eissing <stefan.eiss...@greenbytes.de>
Subject Re: httpd memory consumption
Date Fri, 06 Oct 2017 07:56:40 GMT
Were many threads spawned? Asking for a friend...

> Am 06.10.2017 um 09:46 schrieb Ruediger Pluem <rpluem@apache.org>:
> 
> I am currently looking at a core of a httpd 2.4 process using the event MPM that consumed
a lot of memory
> (core dump file size about 1.4 GB).
> While taking the core actually no request was processed by this process.
> I suspect a memory leak in a 3rd party closed source module.
> As I have no view in the 3rd party module I tried to find out the heap memory usage of
httpd and the included modules.
> 
> For this I used the new dump_pool_and_children I added to .gdbinit which delivers me
the memory used by all
> pools below 'apr_global_pool' and the amount of memory in the allocator free lists associated
to these pools.
> This delivered a usage of only a few MB. Of course I am aware that the process consumes
additional memory for stack,
> static data and text segments, but this usage should be static.
> 
> Is there any heap usage by httpd that I could have missed?
> 
> - We do not use the unmanaged pools from APR. So I should have caught all pools.
> - I do no think that we use allocators that are not used by a pool. Hence I should have
caught all allocators and
>  its free lists.
> - As no request was processed when I captured the core (all worker threads were waiting
for work) I doubt that missed
>  any or at least large memory consuming buckets.
> 
> So possible other consumers of memory apart from the 3rd party module that come to my
mind:
> 
> - Could any of the glibc (httpd was running on a Linux system) functions wrapped by APR
consume a lot of memory?
> - As far as I researched glibc by default should return memory to the OS if more then
128 KB are free at the top of
>  the heap.
> 
> Regards
> 
> RĂ¼diger


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