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From "Spangler, Tim" <>
Subject [users@httpd] Excessive memory utilization with mpm_worker and glibc 2.4+
Date Wed, 21 Nov 2007 19:01:43 GMT
Hello all,

I've been trying to track down a problem with mpm_worker and memory
utilization for a few weeks now.  I think I've narrowed it down (with the
help of Novell) to newer versions of glibc.  I'm currently running Apache
2.2.4 (but the problem exhibits itself on 2.0.58 as well) on Suse Linux
Enterprise Server 10, SLES 9, Redhat AS 2.1, and Fedora Core 7.  Novells
suggestion is to just add more ram to the system, but that answer doesn't
seem very elegant and I can't imagine I'm the first person to discover this

All of the systems are using the following Apache tuning settings, and
Apache was complied from the source at

ServerLimit 80
ThreadLimit 64
StartServers 5
MaxClients 2000
MinSpareThreads 25
MaxSpareThreads 125
ThreadsPerChild 25
MaxRequestsPerChild 0

On the SLES 9 and Red Hat systems (glibc 2.3),   'ps -ea -o
"pcpu,vsz,args,pagein" | grep -i httpd | grep -v grep'    reveals that
apache is using apx 313MB of ram. No problem here, about 2.5MB per thread.  

On the SLES 10 system (glibc 2.4), same Apache build and settings, I find
that Apache is using apx 1179MB of ram, or about 9.25MB per thread.  A 370%
increase in memory utilization. This memory utilization can also be
confirmed via top, free, or whatever other flavor of utility you would like
to use.

It gets even worse on Fedora Core 7 (glibc 2.6), as Apache is using 1425MB
pf ram, or 11.4MB or ram per thread, a 456% increase over glibc 2.3.

Google seaches using the various combinationsof the keywords Apache 2,
glibc, and mpm_worker either return thousands of hits or nearly none.

Is there a way to lower the memory utilization on newer versions of glibc
(assuming the problem is glibc) beyond just lowering the number of spare
threads Apache keeps alive?

Thanks in advance,


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