How to Cluster in Apache Tomcat (Windows)
In a Tomcat production environment, you might have hundreds of web requests per second on a routine basis. With so much volume assaulting your Tomcat server, you'll probably discover that memory resources in one Tomcat JVM (Java Virtual Machine) can become overwhelmed. To help prevent this situation from becoming reality you can place two or more Tomcat servers in a cluster. A cluster is a group of servers that communicate with one another. Now you have multiple JVMs to handle the work load coming in from the network. Session data can be shared among the cluster members to achieve high availability, i.e., recovery of a web session should a server crash occur.
To learn how to cluster in Apache Tomcat, follow these steps:
- Stop the Tomcat server.
- Create a directory under the C: drive named
CATALINA_BASE/confto your new directory.
- Open an edit session on
c:/TomcatA/conf.server.xml. Locate the cluster entry:Note that the entry is commented out.
<!-- <Cluster className="org.apache.catalina.ha.tcp.SimpleTcpCluster"/> -->
- Remove the comment tags:
Note that the entry is commented out.
- Now locate the
Connectorelement for HTTP:
<Connector port="8080" protocol="HTTP/1.1" connectionTimeout="20000" redirectPort="8443" />
- Change the port number to "8181":
We want to change the HTTP port so that there will be no contention for the port when we start our customized Tomcat.
<Connector port="8181" protocol="HTTP/1.1" connectionTimeout="20000" redirectPort="8443" />
- Locate the
<Server port="8005" shutdown="SHUTDOWN">
- Change the port number to "8001":
We also want to change the shutdown port so that there will be no contention for the port.
<Server port="8001" shutdown="SHUTDOWN">
- Save your changes.
- Start a command prompt and navigate to
- Set the environment variable
c:/TomcatA:Now when we start the server, Tomcat will pick up our new configuration, including the updated
- Start Tomcat:
CATALINA_BASEhave different values.
CATALINA_HOMEis the original installation directory that contains our web applications whereas
CATALINA_BASEcontains our customized configuration.
- In your browser, enter the URL that includes the new HTTP port number,
The welcome page will display, indicating the new configuration that includes clustering has been installed by Tomcat.