-XX:MaxPermSize with or without -XX:PermSize

java jvm jvm-hotspot permgen
dimitrisli picture dimitrisli · Dec 2, 2011 · Viewed 294.2k times · Source

We've run into a Java.lang.OutOfMemoryError: PermGen space error and looking at the tomcat JVM params, other than the -Xms and -Xmx params we also specify -XX:MaxPermSize=128m. After a bit of profiling I can see occasionally garbage collection happening on the PermGen space saving it from running full.

My question is: other than increasing the -XX:MaxPermSize what would be the difference if I specify as well -XX:PermSize? I know the total memory then would be Xmx+maxPermSize but is there any other reason why -XX:PermSize should not be there when -XX:MaxPermSize is specified?

Please do share if you have real-world experience dealing with these JVM parameters.

ps. The JVM is HotSpot 64bit Server VM build 16.2-b04

Answer

tobiasbayer picture tobiasbayer · Dec 2, 2011

-XX:PermSize specifies the initial size that will be allocated during startup of the JVM. If necessary, the JVM will allocate up to -XX:MaxPermSize.

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