Load Balancing Issue On Exalogic When Using Different HTTP Client Channel Names For WebLogic Instances
Last updated on SEPTEMBER 02, 2016
Applies to:Oracle Exalogic Elastic Cloud Software - Version 18.104.22.168.0 and later
Oracle WebLogic Server - Version 10.3.4 and later
Information in this document applies to any platform.
In Exalogic environment (applicable to all EECS versions) with WebLogic 10.3.4 version or above installed, issue of requests from proxy webservers redirecting to only one of the WebLogic Managed servers in cluster is observed. In this case web application is hosted on Cluster of multiple Managed Servers. Web application is accessed externally through proxy webserver ( iPlanet/SunOne, Apache, IIS, Oracle HTTP server). Each of the WebLogic Managed servers part of cluster were configured with HTTP Client Channels with different names for e.g. HTTPClient _1, HTTPClient _2, HTTPClient _3 and HTTPClient _4 etc.
Using latest WebLogic plugins and switching WebLogic Cluster type between "Multicast" and "Unicast" also did not fix the issue.
Enabling proxy debug flags and accessing application showed that JSESSION ID is getting constructed with only one managed server JVM ID. The general server list displayed through WebLogic Bridge Config URL contained only one WebLogic managed server IPs even though all managed servers part of WebLogic cluster were UP and RUNNING.
Below is WebLogic Bridge Config debug URL which was used.
At the time of the issue requests from webserver were getting re-directed to one of the WebLogic managed node and Dynamic Server List contained only active server IP details which was serving all the requests. Application requests load from webserver was not getting distributed to other available running managed servers of WebLogic cluster
When turning off Dynamic Server List parameter at web server level issue was not happening, load balancing was working perfectly fine. This is because with Dynamic Server List parameter set to OFF plug-in ignores the dynamic cluster list which was incorrectly showing as only one Managed Server as part of it even though all the Managed servers were up and running. With Dynamic Server List parameter set to OFF plugin uses static list specified with the WebLogicCluster parameter specified in proxy plugin configuration.
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