OpenClinica Tomcat Error When Setting JAVA_OPTS on Ubuntu 10.04

I’ve setup OpenClinica a number of time and never really touched the JAVA_OPTS for Tomcat because I’ve never really had any issues. On the OpenClinica Installation Documentation it states that the JVM performs well when using the following JAVA_OPTS

https://docs.openclinica.com/3.1/installation/installation-linux#content-title-5460

export JAVA_OPTS="$JAVA_OPTS   -Xmx1280m -XX:+UseParallelGC -XX:ParallelGCThreads=2 -XX:MaxPermSize=180m -XX:+CMSClassUnloadingEnabled"

However, if you’re running Ubuntu 10.04 LTS, you will receive an error when modifying the /etc/default/tomcat6 JAVA_OPTS.

Conflicting collector combinations in option list; please refer to the release notes for the combinations allowed

The two options that cause this error are “-XX:+UseParallelGC -XX:ParallelGCThreads=2”, if you remove these then the errors go away. Looking into this further, I’ve found some documentation but not much. The commands are related to garbage collection, and the following article sheds some light on the above two commands as well as “-XX:+UseParNewGC”

http://stackoverflow.com/questions/2101518/difference-between-xxuseparallelgc-and-xxuseparnewgc

Upon remove the two recommended options and adding “-XX:+UseParNewGC” tomcat6 starts without error.

If anyone has any information on why this is, it would be great to know.