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From Ruediger Pluem <>
Subject Re: httpd memory consumption
Date Fri, 06 Oct 2017 08:01:44 GMT

On 10/06/2017 09:56 AM, Stefan Eissing wrote:
> Were many threads spawned? Asking for a friend...

17 by httpd and 12 by the 3rd party module.

Additional information: no mod_http2 loaded :-)



>> Am 06.10.2017 um 09:46 schrieb Ruediger Pluem <>:
>> 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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