$ jmap -heap:format=b `which java` core.647
Attaching to core core.647 from executable /home/xoladm/_JDK/jdk1.5.0_15/bin/java, please wait...
Debugger attached successfully.
Server compiler detected.
JVM version is 1.5.0_15-b04
Finding object size using Printezis bits and skipping over...
Exception in thread "main" sun.jvm.hotspot.utilities.AssertionFailure: BitMap index out of bounds
at sun.jvm.hotspot.utilities.Assert.that(Assert.java:15)
at sun.jvm.hotspot.utilities.BitMap.at(BitMap.java:30)
at sun.jvm.hotspot.memory.CMSBitMap.isMarked(CMSBitMap.java:91)
at sun.jvm.hotspot.memory.CMSCollector.blockSizeUsingPrintezisBits(CMSCollector.java:46)
at sun.jvm.hotspot.memory.CompactibleFreeListSpace.getLiveRegions(CompactibleFreeListSpace.java:100)
at sun.jvm.hotspot.oops.ObjectHeap$LiveRegionsCollector.doSpace(ObjectHeap.java:514)
at sun.jvm.hotspot.memory.ConcurrentMarkSweepGeneration.spaceIterate(ConcurrentMarkSweepGeneration.java:49)
at sun.jvm.hotspot.oops.ObjectHeap.addPermGenLiveRegions(ObjectHeap.java:479)
at sun.jvm.hotspot.oops.ObjectHeap.collectLiveRegions(ObjectHeap.java:559)
at sun.jvm.hotspot.oops.ObjectHeap.iterate(ObjectHeap.java:226)
at sun.jvm.hotspot.utilities.AbstractHeapGraphWriter.write(AbstractHeapGraphWriter.java:34)
at sun.jvm.hotspot.utilities.HeapHprofBinWriter.write(HeapHprofBinWriter.java:399)
at sun.jvm.hotspot.tools.JMap.writeHeapHprofBin(JMap.java:133)
at sun.jvm.hotspot.tools.JMap.writeHeapHprofBin(JMap.java:143)
at sun.jvm.hotspot.tools.JMap.run(JMap.java:71)
at sun.jvm.hotspot.tools.Tool.start(Tool.java:204)
at sun.jvm.hotspot.tools.JMap.main(JMap.java:126)

Note: Solaris 10 x86