Tomcat GC threads

[Chetan Chheda]

All, 

    We are using -XX:+UseParNewGC option in our Tomcat JVMs with 
-XX:ParallelGCThreads=16 on a 6 CPU system. What is the real impact of having a 
higher number of GC threads than the number of CPUs? With the 2 tomcat JVMs 
running on the box, would you recommend changing it to 6 for each tomcat?

Thanks,
Chetan