Load Balancing and Clustering Best Practices - Liferay Portal Performance Best Practices - page 35

Load balancing best practices
We have learned three different methods of configuring the software load balancer
using the Apache Web Server. Now let's learn some of the best practices associated
with these options:
• The software load balancer configuration using mod_jk is most recommended
because mod_jk is a reliable and error free module compared to other options.
From the performance point of view it gives the best performance. The mod_
proxy_ajp module is similar to mod_jk but it is relatively new. If there is a
need to use a secured connection between the Apache Web Server and Liferay
Portal Tomcat server, we can consider using the mod_proxy_http module. It
provides easy configuration to implement this scenario.
• We learned that the Liferay Portal Tomcat server and the Apache Web Server
either connect using the AJP connector or the HTTP connector. None of
the connectors use both the connectors at the same time. The Liferay Portal
Tomcat server, by default, enables both the connectors. It is a best practice
to disable the connector which we are not using. This can save resources on
the Liferay Portal application server. We can disable any of the connectors by
commenting the respective <Connector> tag from the server.xml file of the
Liferay Portal Tomcat server.
• It is advisable to select the load balancer method carefully. Depending upon
the nature of the application, the right load balancer method should be
chosen. If we are using the mod_jk connector, it is recommended to use the
Busyness load balancer method. This will help in distributing requests on
Liferay Portal servers with respect to their current load.
Liferay Portal cluster configuration
In the previous section, we learned about the software load balancer configuration
using the Apache Web Server. In this section, we extend the setup by configuring
the cluster between Liferay Portal Server nodes. To set up a cluster of Liferay
Portal Server nodes, we need to ensure all shared resources are either centralized
or replicated. The following list highlights the resources that need to be handled
for cluster setup:
• Liferay Portal web sessions : For every user conversation, a web session
object is created and managed by the Liferay Portal application server.
A web session object stores important data related to a specific user
conversation. In a clustered environment, it is possible that subsequent
user requests are served by different Liferay Portal nodes. So, it is very
important to make sure that the same session object is available on all
clustered nodes.