PermGen Memory issue after moving one platform to another: what is the default for both of them

Question

I moved my application from IBM JDK (IBM J9 VM ) to OpenJDK 64-Bit Server VM (build 25.131-b11, mixed mode) . In IBM JDK environment we were using WebSphere while in OpenJDK we are using Tomcat .
Things were fine till we got this Exception. The application is happily running in IBM JDK and WebSphere environment.

Exception in thread "ajp-bio-14004-exec-462" java.lang.OutOfMemoryError: PermGen space
java.lang.OutOfMemoryError: PermGen space

Is there anyway I can get to know what is default PermGen for both Java environment by running some command. I searched internet and went through some documents , no luck. I tried kill -3 as well.

Answer 1

Hotspot build 25.131-b11 looks like an OpenJDK 8 version, however OpenJDK 8 will not throw the PermGen space OutOfMemoryError exception. The code for throwing it is just not there anymore because the permanent generation was removed from the garbage collectors.

Are you sure you are running your application with the intended JVM?

Answer 2

It depends on each JVM On IBM the DTFJ overview tool should provide the information,

For OpenJDK you can try to use jvisualvm or jconsole UI tools or command line utils.