I've recently been evaluating switching from ParallelOldGC to ConcurrentMarkSweet for tenured generation GC, and have noticed that jmap is no longer able to display a heap breakdown after switching to CMS.
See the message below: "unknown generation type", followed by all the 0 values. Is this a known bug with jmap.
I'm running Java 1.6 Update 29 on SPARC. The JVM is 64-bit.
Before switching to CMS, jmap was successfully able to provide memory breakdowns and didn't display the error "unknown generation type".
$ /usr/java/bin/jmap -d64 -heap 388
Attaching to process ID 388, please wait...
Debugger attached successfully.
Server compiler detected.
JVM version is 20.4-b02
using parallel threads in the new generation.
using thread-local object allocation.
Concurrent Mark-Sweep GC