Re: [users@httpd] performance prob due to httpd's piling up

[Bennett Haselton <bennett@xxxxxxxxxxxxx>]

Apache/2.0.52, CentOS 4, Dell Pentium 4 3.0 GHZ, 1 GB RAM.

Right now the output is:
>>>
[root@server1 ~]# free -m
             total       used       free     shared    buffers     cached
Mem:          1009        993         15          0          0         10
-/+ buffers/cache:        982         26
Swap:         2047       1672        374
>>>

but I think that's because a process called webalizer is running which must 
be what they use to parse the day's logs.

So is there a reason those extra instances of httpd keep hanging around in 
memory when there's nothing left for them to do, and would it increase 
performance if I could make them go away?

        -Bennett

At 11:39 PM 5/7/2006 -0500, Graham Frank wrote:
> Hey,
>
> What OS?  What version of Apache?  Could you show us an output of "free 
> -m"?.  What are the server specs?
>
> --Graham
>
> -----Original Message-----
>
> From:  Bennett Haselton <bennett@xxxxxxxxxxxxx>
> Subj:  [users@httpd] performance prob due to httpd's piling up
> Date:  Sun May 7, 2006 11:24 pm
> Size:  1K
> To:  users@xxxxxxxxxxxxxxxx
>
> I was running a stress test on a site that I run called
> StupidCensorship.com which frequently slows to a crawl due to high
> traffic.  From running a stress test on it using "ab" that sent 1,000
> concurrent requests to the site, I found that the number of running
> instances of /usr/sbin/httpd would rise from its initial default number of 
>
> 22, up to 258, and then stay steady at 258.  While the number was between
> 22 and 258, the site performance was still OK, but once it hit 258, the
> response time was a lot slower.  I'm guessing this has something to do 
> with
> the fact that while the number is climbing, the machine can just spawn a
> new instance of httpd to handle the request, but once it hits the maximum
> (due to hardware limits, I guess), new requests just get queued.
>
> Do these symptoms suggest any obvious way to improve performance, besides
> getting more RAM?  (And even more RAM would, I assume, only raise the 
> limit
> of "httpd" instances that could run, but it would still plateau once it 
> hit
> that limit.)
>
> One possibility: I noticed that even after the stress test was over, the
> number of running 'httpd' instances would fall very slowly, about one per
> second, until it got back down to 22.  I thought they were keeping the
> connection open, but my httpd.conf has KeepAlive set to Off.  If I could
> somehow get the httpd instances to just exit memory once they were done,
> instead of hanging around, would that solve the performance problem 
> without
> any negative side effects?
>
>         -Bennett
>
> bennett@xxxxxxxxxxxxx     http://www.peacefire.org
> (425) 497 9002
>
>
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