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From "Ahmed Musa" <donald1...@gmx.at>
Subject Questions to some mod_jk Options
Date Wed, 27 Feb 2008 16:47:13 GMT
Hallo,
I studied the mod_jk docs and the following questions about mod_jk Options are haunting me
- i hope wrote the questions in an understandable form and i am pleased of getting hints and
tips.

.) retries (for LB workers) 
-> At the Apache we use he prefork MPM. So how big is the connection_pool ?
because a retry of a lb-worker happens if the loadbalancer can not get a free connection for
a member worker from the pool (Info from the doku).
Does it depends on the Apache prefork Parameters MaxClients and MaxRequestsPerChild ?
If it is so - we have MaxClients 500 and MaxRequestsPerChild 10000 => this means the webserver
can send/handle 5000000 requests ?
-> is this the size of our connection_pool? - i don't think so.
On the other side we have 36 Tomcat instances - each Tomcat has - maxThreads=300 on the AJP
connector. => ?this doesn't fit, or?
(And 3 Apache as frontend - all configured the same)
In the worker model i think the number of threads must correspond to the max threads of the
Tomcat - but how does it work in our prefork model?

.) Why does a load-balancer retries to get a free connection for a member worker from the
pool ? Why doesn't he use another member worker ?

.) reply_timeout - does it only work between the request and the first response packet or
between each two response packets. Is a response packet an AJP-packet with 8k default size
?

.) what is the socket_timeout good for ?
We configured a connection_timeout, a prepost_timeout and a reply_timeout => i can't find
a situation where i need an additional socket_timeout ?
And when i wants to know what happens in my system - i think i need a more "higher level"
failure message to evaluate the situation - but on socket level ?

.) this question concerns to the mod_jk options "retries" (for "normal" worker) (hint - better
to find an other Name - the same name for two different things makes problems when writing
about) in association with the recovery_options.
=> when i use the value 7 for the recovery_option - Bit 1+2+4 => i think a retry is
only possible if the connection timeout matches.
- not on the prepost_timout and not in the situation of reply_timeout => is this right
?

Another question to the same topic: i have a long running sticky session - this means that
in this session are many requests against the same Tomcat.
Will there be established a new connection for each request ? or will there be used the established
connection for all requests?

If second - that means the established connection is used for all requests of the session
=> than a retry will not happen if during
the session the Tomcat causes Problems. (with recovery_options 7). - is this right?

Version mod_jk 1.2.26 (upgraded recently)  

Here my worker.properties

worker.properties

worker.list=ajp_bam,ajp_ggi,ajp_ad,ajp_svp,.......,jkstatus

worker.template.type=ajp13
worker.template.lbfactor=5
worker.template.socket_keepalive=1
worker.template.connect_timeout=7000
worker.template.prepost_timeout=5000
worker.template.reply_timeout=180000
worker.template.retries=20
worker.template.activation=Active
worker.template.recovery_options=7

worker.lbtemplate.type=lb
worker.lbtemplate.max_reply_timeouts=6
worker.lbtemplate.method=Session

#Produktions Worker
# AS-INETP101 - 106 - 6/6 GGI
worker.INETP1011.host=AS-INETP101.AEAT.ALLIANZ.AT
worker.INETP1011.port=65001
worker.INETP1011.reference=worker.template
....many more of the same
then
worker.ajp_ad.reference=worker.lbtemplate
worker.ajp_ad.balance_workers=INETP1032,INETP1062
.... many more portals
at least jkstatus

The JKMount is very simple
JkMount /* ajp_ad    --- for the other portals mostly the same

The Portals are Virtual Hosts on the Apache.

Tomcat - server.xml
example
<Connector port="65001" maxThreads="300" protocol="AJP/1.3" />
     <Engine name="Catalina" jvmRoute="INETP5021"
defaultHost="default">
 ......
<Host name="slfinsol.com" appBase="webapps" unpackWARs="true"
 autoDeploy="false" deployOnStartup="false" xmlValidation="false"
 xmlNamespaceAware="false">
      <Alias>www.slfinsol.com</Alias>
      <Alias>web1.slfinsol.com</Alias>
      ...
      <Alias>testweb.slfinsol.com</Alias>
      .....
      <Valve className="org.apache.catalina.valves.AccessLogValve"
       directory="logs" prefix="swl_access_log." suffix=".txt"
       pattern="common" resolveHosts="false" />
     <Valve className="at.allianz.tomcat.valve.RequestTimeValve"/>
     <Valve className="at.allianz.tomcat.valve.WebcollaborationWorkaroundValve"/>
   <Context path="" docBase="swl" />
   <Context path="/monitor5" docBase="monitor" />
   <Context path="/swl" docBase="swl" />
</Host>    

thanxs for your time reading this and maybe giving tipps - 
with kind regards
ahmed musa
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