After running QueueMetrics for a while, the JVM stops with the exception "OutOfMemoryError: unable to create new native thread". This is usually caused by using the wrong JVM / Tomcat / Linux Kernel set, and is usually solved by:

• Installing a newer (or older) JDK, or one that is designed right for your hardware
• Installing a newer (or older) Tomcat version

QM will run just fine with any JDK >= 1.4.2 and Tomcat >= 4.0, so there is usually no great benefit in running the very latest version of them.

See also: Java thread tuning.