Garbage Collection Options and Functions

Garbage collection options:

In addition to one of the previous posts regarding memory management options in various JVMs, now it is time to present some options for the GC (Garbage Collector)

Select specific collector:

• -XX:+UseSerialGC
• -XX:+UseParallelGC
• -XX:+UseParallelOldGC (combine with -XX:+UseParallelGC)
• -XX:+UseConcMarkSweepGC
• -Xnoclassgc is to disable garbage collection for permanent generation

Tune the Parallel GC:

• -XX:ParallelGCThreads=n - limit parallel threads by 'n'
• -XX:MaxGCPauseMilis=n - limit pause in miliseconds
• -XX:GCTimeRatio=n - throughput (percentage of CPU time spent on application

Increase debug level:

• -XX:+PrintGC - get basic information
• -XX:+PrintGCDetails - get verbose information
• -XX:+PrintGCTimeStamps - add timestamps
• -XX:+HeapDumpOnOutOfMemoryError very useful :)