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From Rainer Jung <rainer.j...@kippdata.de>
Subject Re: Clustering with mod_jk
Date Sat, 02 Sep 2006 19:57:51 GMT
You should try 1.2.18 and depending on your time frame update to 1.2.19
once it's being released this month.

We improved load balancing code and with 1.2.19 also the observability
of what's happening.

Try the alternative method B (Busyness) for the load balancer in 1.2.18.

The default method tries to send equal numbers of requests to the
different balancing targets. Once a target gets slow/stuck, it will
accumulate hanging requests, until it gets detected as being in error.
So using good timeout values, using cping/cpong and recovery_options are
good ways to improve stability of load balancing.

Regards,

Rainer

Edoardo Causarano schrieb:
> 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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