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Posted to users@httpd.apache.org by Travis Whitton <ti...@gmail.com> on 2010/09/01 21:46:07 UTC

Re: [users@httpd] Slow Responses Under Low Load

Pretty sure we're hitting up against a concurrency problem. I can
reproduce the issue on a machine that's not in production with very
similar specs by running ab (apache bench) on three hefty client
machines with concurrency set to 1,000 on each machine. Doing some
tests serving static content, I changed my config from prefork to
worker, and the situation improved quite a bit; however, the PHP
modules our site uses aren't thread-safe, so that's not a practical
choice for the moment.

On Tue, Aug 31, 2010 at 5:55 PM, Rainer Jung <ra...@kippdata.de> wrote:
> On 31.08.2010 23:38, Eric Covener wrote:
>>>
>>> Running `netstat -tapn | grep 80 | wc -l' shows 11299
>>> connections to port 80. We're setup to use prefork with the following
>>> configuration.
>>>
>>> MaxClients        1000
>>
>> Is the netstat output a typo?  With MaxClients 1000 and the default
>> ListenBackLog of ~500, you should have started refusing connections
>> long ago.
>
> Likely most of them are TIME_WAIT. Those are not connected any more, but to
> many of them make the TCP connection hash slow on many platforms.
>
> If the OPs output is like mine, he can get a better statistics via:
>
> netstat -tan | awk '/:80 / {print $NF}' | sort | uniq -c
>
> Regards,
>
> Rainer
>
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Re: [users@httpd] Slow Responses Under Low Load

Posted by Eric Covener <co...@gmail.com>.
On Wed, Sep 1, 2010 at 3:46 PM, Travis Whitton <ti...@gmail.com> wrote:
> Pretty sure we're hitting up against a concurrency problem. I can
> reproduce the issue on a machine that's not in production with very
> similar specs by running ab (apache bench) on three hefty client
> machines with concurrency set to 1,000 on each machine.

Your MaxClients is set to 1,000, what are you expecting when sending
3,000 concurrent clients at it?

-- 
Eric Covener
covener@gmail.com

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