Java Concurrent and Parallel GC

Question

This article here suggests to use -XX:+UseParNewGC \"To enable a parallel young generation GC with the concurrent GC\".

My confusion is that in order

Answer 1

ParNew is the default young generation collector when CMS is used.You just have to specify -XX:+UseConcMarkSweepGC to use CMS and ParNew will be used by default. CMS is a good collector if avoiding GC jitters is of higher priority but if throughput is more important for eg for a batch like job the default SUN parallel collector does a better job.