Here are some OSS projects to monitor your tomcat instances (f.e. memory-/cpu-usage, sessions, mbeans)
Off course you can also monitor your tomcat via VisualVM (http://visualvm.java.net/ or included in JDK6)
Update: Or use JRDS http://jrds.fr/
Today i had to do some merging of artifacts (code and pom.xml). Then i wondered, why the tests didn’t run properly.
java.lang.OutOfMemoryError: Java heap space” was the reason. But why? I didn’t change the tests and i carefully merged the configuration. So i connected VisualVM to the surefire process and saw that only ca. 67MB max heap were available. I reviewed my MAVEN_OPTS, but my settings didn’t apply…
The culprit is a bug. See http://jira.codehaus.org/browse/SUREFIRE-501.
The workaround is to place your max heap configuration in the configuration section of the plugin. As seen in the linked bug issue:
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