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From Filip Hanik - Dev Lists <devli...@hanik.com>
Subject Re: Clustering with mod_jk
Date Fri, 01 Sep 2006 20:23:54 GMT
it is a mod_jk issue, it uses permanent connections, that is how it was 
designed. setting MaxRequestsPerClient to 1, will kill the child, hence 
kill the mod_jk connection, this way, you can have 
maxProcessors<MaxClients otherwise, they must match

Filip


Edoardo Causarano wrote:
> Using mpm_worker gave less impressive results; I'd say about 1/2, a 
> much worse load average (way more than 5), and lots of swap. Seems 
> like prefork works better on linux and I'm surprised. Anyway, assuming 
> that I got the maxProcessors wrong I should have seen queues building 
> up @ 150*4 instead they start < 50% that value.
>
> The thing that makes me think it's a mod_jk issue is the fact that 
> suddenly all request flow locks onto a node and stays busy until I 
> restart apache.
>
> e
>
> On 01/set/06, at 21:21GMT+02:00, Filip Hanik - Dev Lists wrote:
>
>> since you are using prefork, you must set cachesize=1 for your 
>> workers.properties file.
>> However, you have 4096 MaxClients, in order to serve this up in 
>> tomcat, your JK connector should have maxProcessors="4096".
>> An alternative, and safe solution, although much less performance, is 
>> to set "MaxRequestsPerChild 1", this way you can get away with 
>> MaxClients 4096 and still have a much less maxProcessor value on Tomcat
>>
>> Filip
>>
>>
>> Edoardo Causarano wrote:
>>> Hello List,
>>>
>>> scenario:
>>>
>>> - 4 node tc 5.0.28 vertical cluster ( :-| same server... still 
>>> testing, but it could have been 8) listening on ajp
>>> <Connector address="x.x.x.x" port="8009"
>>>     maxProcessors="150" minProcessors="50"
>>>     protocol="AJP/1.3" 
>>> protocolHandlerClassName="org.apache.jk.server.JkCoyoteHandler"
>>>     redirectPort="8443">
>>>
>>> - 1 httpd 2.0.52 with mod_ajp 1.2.15 and prefork config on RH AS4, 
>>> kernel 2.6.9-5.EL
>>>     sticky sessions are disabled to avoid stress scripts hitting 
>>> only one node
>>>
>>> <IfModule prefork.c>
>>>     StartServers       40
>>>     MinSpareServers    80
>>>     MaxSpareServers    280
>>>     ServerLimit        4096
>>>     MaxClients         4096
>>>     MaxRequestsPerChild  4096
>>> </IfModule>
>>>
>>> - 1 application where a couple of thousand users should hammer the 
>>> app deployed on the webapp
>>>
>>> What happens is the app takes the stresser for a ride until 240 
>>> circa users then starts to die; jkmonitor sees linear increase on 
>>> busy and max requests on only one node and pages hang; disabling the 
>>> node moves the hung request handling to the next node.
>>>
>>> Where's the bottleneck? Any known bug in mod_jk? Should I increase 
>>> threads on the tomcat nodes?
>>>
>>> Tnx,
>>> e
>>>
>>>
>>>
>>>
>>>
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>>>
>>>
>>
>>
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>
>
> ---------------------------------------------------------------------
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>
>
> --No virus found in this incoming message.
> Checked by AVG Free Edition.
> Version: 7.1.405 / Virus Database: 268.11.7/435 - Release Date: 8/31/2006
>
>


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