satya - Thursday, April 14, 2011 2:57:28 PM

Understanding Java Memory Settings

Summary:

if max memory exceeds you get out of memory exception

good to set both mn and mx values the same

satya - Thursday, April 14, 2011 2:58:52 PM

jvm tuning

This links talks about why the two mn and mx values need to be close or same

satya - Thursday, April 14, 2011 2:59:37 PM

Garbage collection tuning from sun

satya - Thursday, April 14, 2011 3:08:19 PM

jvm tuning faq from sun/oracle

satya - Thursday, April 14, 2011 3:08:48 PM

turbo charging hotspot vm

satya - Thursday, April 14, 2011 3:10:37 PM

Key excerpt for the default garbage collector from the link above

Best results on J2SE1.4.1 using the default garbage collectors in the young and old generations for the chosen size of the JVM heap:

java -Xmx512m -Xms512m -XX:MaxNewSize=24m -XX:NewSize=24m -XX:SurvivorRatio=2 (application)

Average GC pause in old generation: 3 secs. 
Average GC pause in young generation: 110 ms. 
GC sequential overhead: 18.9%