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From William Taylor <willi...@corp.sonic.net>
Subject Re: apache 2.2 can't keep up with apache 1.3
Date Mon, 12 Mar 2012 17:07:56 GMT
On 3/8/2012 1:10 PM, William Taylor wrote:
> We have written a modules for apache that for certain reasons requires
> one hit per child.
> On apache 1.3 this worked fine with a minor tweak to
> SCOREBOARD_MAINTENANCE_INTERVAL
> setting it to 10000 from 1000000.
>
> Note that this behavior can be tested without our module by setting
> "MaxRequestsPerChild 1"
>
> We have been running apache 1.3.41 with:
> MinSpareServers 500
> MaxSpareServers 600
> StartServers 550
>
> Using JMeter to send some requests if we request a single page using 3
> threads, apache has no problem keeping up and
> doesn't dip below 485 idle servers. With debug logging on you see it
> jumping from spawning 8 to 16 to 32 children. We didn't
> need to increase the MAX_SPAWN_RATE from the default of 32 for apache to
> keep up just fine.
>
> Output from apachectl status
>    197 requests/sec - 28.6 kB/second - 148 B/request
>    5 requests currently being processed, 492 idle servers
> ________________________________________________________________
> __________________________.___._________________________________
> ________________________________._____________________________..
> __.___._.W_WW..WW_______________________________________________
> __________..__________________._..______________________________
> ________________________________________________________________
> ________________________________________________________________
> ____________________________________....._..._.___________..__..
> ........._________.____.........................................
>
>
> Recently we decided we should update our module for apache 2.2 . However
> we found the performance of apache 2.2 was falling short
> compared to apache 1.3.
>
> Running apache 2.2.22 with the same number of servers falls down pretty
> quickly with the same load from JMeter.
> Within a few seconds it drops down to 0 idle connections. In the
> error_log you see apache constantly saying it's spawning
> 32 children but the number of children are really low.  Example log
> entry "spawning 32 children, there are 2 idle, and 9 total children"
> Occasionally it will start catching up but quickly drop back down.
> Example log entry "spawning 32 children, there are 169 idle, and 180
> total child"
>
> apachectl status:
>    27.8 requests/sec - 7.0 kB/second - 256 B/request
>    13 requests currently being processed, 0 idle workers
>  CCCWCWRSSS............................CCCCCC....................
>  ................................................................
>
>
> apachectl status when it starts catching back up:
>   161 requests/sec - 11.4 kB/second - 72 B/request
>    4 requests currently being processed, 477 idle workers
>  ___________C____WR____________________._________________________
>  ________________________________________________________________
>  ________.______.._......_...C___________________________________
>
>
> I have tried upping the MAX_SPAWN_RATE to 512 and starting off the
> idle_spawn_rate at 128 and never letting
> it fall below that. It seemed like things got marginally better but not
> by much. I realize most people would think
> we are crazy for running one hit per child but it's just something we
> need to do. This has all been tested on the
> same hardware also. I tried stracing and running gprof but nothing
> seemed obvious. My best guess at this point
> is apache is taking to long to close connections or there is some other
> sleeps or something that I'm not seeing.
>
> Any thoughts on what could be the issue would be most appreciated.
>
>

By the lack of response from anyone, should I assume I posted this to
the wrong list or
is this a known problem that no one wants to acknowledge?
In case of the first ill try posting to the bugs list in hopes of some
sort of response.

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