What is -XX:MaxPermSize in JAVA_OPTS?

Question

In a JBoss server configuration java options are given as below.

JAVA_OPTS="-Xms128m -Xmx6144m -XX:MaxPermSize=128m

As of my understanding -Xms and -Xmx are minimum and maximum memory(RAM) allocating to JBoss to run the server. What is the meaning of -XX:MaxPermSize in this one? And what is the preferred value for this?

Sergio Escudero · Answer 1 · 2017-07-03T09:03:42.223

2

-XX:MaxPermSize and -XX:PermSize are used to reserved memory for the permanent memory area.

This is where the class and methods definitions are stored.

It is outside the Heap.

By default, the size is 64 MB (it depends on Operating System, JVM,...).

Be aware that if you use reflection it could be full in a period short of time. So if you use Spring, be aware of this.

The best is that you activate gc log and show what happens when your app is running.

Permgen has been removed in Java 8.

Hope it helps!

edited Jul 03 '17 at 09:03

answered Jun 30 '17 at 12:47

Sergio Escudero

143
9

https://stackoverflow.com/a/12114284/1075369 – 23nikoloz Jun 30 '17 at 12:53
@Sergio Thanks for this detailed explanation. Its and Java based ERP(ADempiere3.7) I'm now dealing with. Its a Swing based ERP. So JBoss server is running. What can be the preferred value for the MaxPermSize in this scenario? – Sajeev Jun 30 '17 at 12:54
1

You forgot to mention that Permgen was removed in Java 8 and the corresponding command line options are now ignored. – Stephen C Jun 30 '17 at 12:56
@StephenC, oops! I forgot! I had in mind but I forgot it. – Sergio Escudero Jun 30 '17 at 13:00
@Sajeev depends on the app. My advice is to active GC log and see what happens. As initial value 128 Mb would be ok, but really, activate the GC log. – Sergio Escudero Jun 30 '17 at 13:02
@SergioEscudero Thanks. I will see to activate GC first and update here once done. – Sajeev Jun 30 '17 at 13:07
@Sajeev, could you mark my answers as ok or valid? thank you – Sergio Escudero Sep 25 '17 at 15:45

What is -XX:MaxPermSize in JAVA_OPTS?

1 Answers1