Java processes can often consume more memory than any other application running on a server.

Java processes can be passed a -Xmx option. This controls the maximum Java memory heap size. It is important to set a limit on the heap size, otherwise the heap will keep increasing until you get out of memory errors on your VPS (resulting in the Java process – or even some other, random, process – dying.

Usually the setting can be found in your /usr/local/jboss/bin/run.conf or /usr/local/tomcat/bin/setenv.sh config files. And your RimuHosting default install should have a reasonable value in there already.

If you are running a custom Java application, check there is a -XmxNNm (where NN is a number of megabytes) option on the Java command line.

The optimal -Xmx setting value will depend on what you are running. And how much memory is available on your server.

From experience we have found that Tomcat often runs well with an -Xmx between 48m and 64m. JBoss will need a -Xmx of at least 96m to 128m. You can set the value higher. However, you should ensure that there is memory available on your server.

To determine how much memory you can spare for Java, try this: stop your Java process; run free -m; subtract the ‘used’ value from the “-/+ cache” row from the total memory allocated to your server and then subtract another ‘just in case’ margin of about 10% of your total server memory. The number you come up with is a rough indicator of the largest -Xmx setting you can use on your ser