Jboss/cluster performance issue

[golia]

Hello,

I have an application using one SLSB and many servlets running on Jboss 3.2.1 with a two nodes cluster. My issue is that when both nodes in the cluster are running, the performance (time it takes for the browser to display the page) of my application drops by 50%.

If I turn one of the nodes off, performance is where it should be compared with the same application deployed in weblogic 5.1 running in a two nodes cluster.

At fisrt I thought the amount of DEBUG information dumped in the server.log was the problem but after turning the log4j threshold to INFO the performance has not improved.

It seems that when both servers are up they spend an enormous amount of time replicating the HTTP session and the EJB.

My questions are:

1. does any one have the same problem?
2. is there a jboss/cluster tuning guide?
3. which config file can I post that would help diagnose the issue?

Thank you in advance for any help.

golia

[mattsmith]

A little more info..

With clustering enabled, any system activity generates ridiculous amounts of UDP multicast and unicast traffic. tcpdump logged over 10,000 cluster-related packets as a result of a single click in our application.

There are vague references in the documentation to some settings that seem to be related to how often state information is replicated between cluster nodes

never
neither

However these settings are not being accepted, nor are the possible options and when you might use them actually explained.. the above is just the example settings from the documentation..

Anyone have ANY comments?

[ericmolitor]

1) Try using and downloading 3.2.2rc4
2) The interval options are in deploy\jbossweb-tomcat41.sar\META-INF\jboss-service.xml and the values are configured with...

<!--
If you are using clustering, the following two attributes
define when the sessions are replicated to the other nodes.
The default value, "instant", synchronously replicates changes
to the other nodes. In this case, the "SnapshotInterval" attribute
is not used.
The "interval" mode, in association with the "SnapshotInterval"
attribute, indicates that Tomcat will only replicates modified
sessions every "SnapshotInterval" miliseconds at most.
-->
instant <!-- you may switch to "interval" -->
2000

3) Make sure you specify your tomcat/mod_jk route! (Search the forum for info on this)

You still wont replicate as fast as Weblogic 5.1 did, but this should get you a lot closer.

- Eric Molitor

[mattsmith]

Minor detail left out - we were using jbossweb-jetty instead of tomcat.. Those options were not available with jetty.

I have since tried Tomcat and it seems to be working better.. I've got it running approximately the same speed as unclustered.. even with the replication frequency set to instant..