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From Alex Bligh <>
Subject Re: [users@httpd] Unbelievable : one single apache process uses more than whole server memory (5 gigabytes) !
Date Sat, 18 Aug 2012 08:29:08 GMT

--On 18 August 2012 10:04:12 +0200 Denis BUCHER <> 

> And whatever page it is, is there some explanation why apache can takes
> all the server memory ? PHP is limited, so how is it possible for Apache
> to do that ?

Right, but it's taking lots of virtual memory, and that appears to
be larger than your physical memory. The pmap manpage is woefully
short but I think that's what it's saying. That itself isn't a problem.
Perhaps it's just mmap'ing a large file, for instance? Or allocating
3G of virtual memory with an anonymous mmap (which might be
what '[anon]' means). Assuming you are on a 64 bit server, you are
never likely to run out of virtual memory. So, is it writing to
that an actually using huge quantities of physical memory? IE
does RSIZE on 'top' grow huge? If not, I wouldn't worry. If so,
I'd guess something is allocating a large or several large objects,
as IIRC libc uses anonymous mmap rather than brk only for large
allocations. I wouldn't necessarily trust php_memory_limit. So,
either a memory leak in php, apache or the postgres client, or
you have a script sending back a huge reply, or a DB query with
a huge reply, or something else. What I'd do is wait until it
happens again and strace the pid concerned and see what it's

Alex Bligh

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