Why the committed heap size is more than the max heap size, while monitoring by CLI/JConsole?

Solution Unverified - Updated -

Environment

  • Red Hat JBoss Enterprise Application Platform (EAP)
    • 6.x

Issue

  • Why the committed heap size is more than the max heap size, while monitoring by CLI/JConsole?
  • I get the committed, used, and max heap sizes from CLI, Sometimes I see the committed heap size is more than the max heap size.
  • Sometimes Jconsole is showing the same inconsistency.
  • We are using Oracle JDK 1.7.0_40

Resolution

  • Jconsole and the JBoss CLI are just reporting values returned by the JVM. They both show the same incorrect value suggesting the JVMs returns are incorrect and JBoss isn't misinterpreting it.

  • As this is the JVM's which has the code to calculate the committed, used, and max heap. JBoss or any other MBean client utility or java code running on that JVM just extracts these memory related data from the JVM. Hence users need to contact the JVM vendor to get a clarification on the same.

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