Bonjour Robert.

From experience with this kind of problems, you need to check what script (php 
or other) is served by that process at the moment it takes that much ram.

The first thing you need to look is was the httpd process is responding to. If 
it's not, switch the ExtendedStatus to on, and then permit the access to 
/server-status to your station or network.

Now, access the servername/server-status page in your web browser. You will see 
there what is the virtualhost (if any) and query that is serving for what 
process id.

If you used your own compile of apache, it'll be compiled with mpm=prefork, and 
so one precess will have one thread and it'll be easier to spot.

If it is compiled with mpm=worker (I don't know if centos' httpd compiled that 
way), then each process will serve many thread. If the process you examin is 
serving several page, it'll be more difficult to spot. From the number of 
process you have, either it's a low-traffic server or it use mpm=worker. If you 
got 10 process at 15 megs, plus one at 100 megs, that sums up to 250 megs. How 
much memory you server has ?

Now that you have identified that, you need to trace where the memory hug is in 
that particular language.

One of the advantage of mpm=prefork is that it isolates potential problem from 
one process to the other, but it takes more ram. So if you server is compiled 
with mpm=prefork, you can re-compile it with mpm=worker, it'll take less 
ressources on the server side. If your're using php, then you must re-compile 
php as well.

Best regards,
Nicolas


Le 2010-11-26 à 16:06, Pascal Robert <prob...@macti.ca> a écrit :

> I'm trying to fix a CentOS (5.5 x86_64) VM that we have where it become 
> unstable due to swapping. But I did notice something: I have 10 httpd 
> processes, and 5 of them are using 13 MB of resident memory, the other are 
> using between 91 and 96 MB of RAM. I find it quite strange to see such 
> differences in RAM usage. I ran a "lsof -P -p" on the processes, and I didn't 
> see any major differences, so I'm wondering what is the best way to know what 
> the processes are doing?
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