E-mailThe default Java Virtual Machine is not adequate to run an application of Sakai's size, and several JVM parameters must be increased to a certain threshold for Sakai to run, while some may be further adjusted for optimal performance on your machines.
JVM tuning is, as a general rule, something of a black art, and we recommend that you take the time to experiment with different memory and garbage collection settings and see what works best in your environment. We can make some minimal recommendations that should serve as a foundation for further experimentation and testing, but the following details are however offered only as samples or suggestions, and we recommend that you consult a systems administrator or local Java guru before making any such changes to a production system.
The standard way to control the JVM options when Tomcat starts up is to have an environment variable JAVA_OPTS defined with JVM startup options in the TOMCAT_HOME/bin/setenv.sh (or .bat) file. Since any given Sakai instance may be deployed for a variety of purposes - ranging from developers doing private testing to large-scale deployments - it's hard to recommend a single set of such options as the preferred ones for every case. We can, however, start with a bare minimum which will at least avoid "Out of Memory" errors, and be suitable for developer installs of the software:
JAVA_OPTS="-server -XX:+UseParallelGC -Xmx876m -XX:MaxPermSize=2160m -Djava.awt.headless=true"
This is an adequate - if minimal - starting point: it selects server mode, sets an adequate heap size, and sizes the permanent generation to accommodate the large number of classes in Sakai. These settings will allow things to be functional for testing and development, but for pilot or production deployments you'll want to give closer attention to the appropriate values for your server. See the Sys Admin Guide for more detailed tips.
If you choose to run Tomcat as a service, review the Tomcat Installation and Configuration section for additional tuning recommendations.