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From Filip Hanik - Dev Lists <devli...@hanik.com>
Subject Re: Session Replication in Cluster
Date Mon, 06 Apr 2009 07:53:09 GMT
what you're seeing is correct.
the server did fail over, and by changing the session id, it ensures 
that it does not do "fail back"

Filip

Roy McMorran wrote:
> Hello all,
>
>
> I've built a very simple 2-member Tomcat cluster for testing, but I am 
> unable to get the session replication quite right.  The problem is 
> when I fail one member of the cluster.  The behavior I was expecting 
> is that the other cluster member would take over the session ids for 
> the failed member.  However it is appending it's own jvmRoute value to 
> the session id, and thus setting a new cookie.
>
>
> Details:
> I have 2 cluster members, "itchy" and "scratchy", running on the same 
> physical server, and CATALINA_BASE is /var/tomcat/itchy and 
> /var/tomcat/scratchy respectively.  Tomcat 6.0.18 binaries, etc. are 
> at /usr/local/tomcat.  Using mod_jk 1.2.27 on Apache 2.2.11 (Apache is 
> also on the same server).  I am using sticky sessions.
>
>
> Here are the access logs for the 2 members from a short "failover" 
> experiment (note I'm including the session ID in the 2nd field).  The 
> session starts on scratchy.  From scratchy_access_log.2009-04-02.txt:
>
> 192.168.200.177 E5BF3FFA9AEE1E3AB0DD4A96BA5E4011.scratchy - 
> [02/Apr/2009:10:19:55 -0400] "GET / HTTP/1.1" 200 14612
> 192.168.200.177 E5BF3FFA9AEE1E3AB0DD4A96BA5E4011.scratchy - 
> [02/Apr/2009:10:20:14 -0400] "GET /about/ HTTP/1.1" 200 19507
>
>
> At 10:21:39 AM I do a kill -9 on the scratchy instance.  Now the 
> traffic goes to the other cluster member as expected.  From 
> itchy_access_log.2009-04-02.txt:
>
> 192.168.200.177 E5BF3FFA9AEE1E3AB0DD4A96BA5E4011.itchy - 
> [02/Apr/2009:10:22:11 -0400] "GET /about/publications/ HTTP/1.1" 200 
> 18263
> 192.168.200.177 E5BF3FFA9AEE1E3AB0DD4A96BA5E4011.itchy - 
> [02/Apr/2009:10:22:32 -0400] "GET /about/changes/ HTTP/1.1" 200 12736
>
>
> Note however that the new member's jvmRoute value is now appended to 
> the session id.  I thought is was supposed to stay exactly the same 
> after failover.
>
>
> Additional details can be found as follows:
>
> server.xml for "itchy" - see:
> http://gillnet.mdibl.org/~mcmorran/itchy-server.xml.txt
>
> server.xml for "scratchy" - see:
> http://gillnet.mdibl.org/~mcmorran/scratchy-server.xml.txt
>
> context.xml (identical) - see:
> https://gillnet.mdibl.org/~mcmorran/context.xml.txt
>
> workers.properties:
> https://gillnet.mdibl.org/~mcmorran/workers.properties
>
> I've also included the catalina.out file for both, from startup and 
> through the test at:
> https://gillnet.mdibl.org/~mcmorran/itchy-catalina.out
> https://gillnet.mdibl.org/~mcmorran/scratchy-catalina.out
>
>
> I'd appreciate any advice on where I went wrong.  Thanks and best wishes,
> Roy
>


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