jmap does not work with G1:

Exception in thread "main" java.lang.reflect.InvocationTargetException
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:39)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)
at java.lang.reflect.Method.invoke(Method.java:597)
at sun.tools.jmap.JMap.runTool(JMap.java:179)
at sun.tools.jmap.JMap.main(JMap.java:110)
Caused by: sun.jvm.hotspot.utilities.AssertionFailure: Expecting GenCollectedHeap or ParallelScavengeHeap, but got sun.jvm.hotspot.gc_interface.CollectedHeap
at sun.jvm.hotspot.utilities.Assert.that(Assert.java:32)
at sun.jvm.hotspot.oops.ObjectHeap.collectLiveRegions(ObjectHeap.java:592)
at sun.jvm.hotspot.oops.ObjectHeap.iterate(ObjectHeap.java:249)
at sun.jvm.hotspot.utilities.AbstractHeapGraphWriter.write(AbstractHeapGraphWriter.java:51)
at sun.jvm.hotspot.utilities.HeapHprofBinWriter.write(HeapHprofBinWriter.java:416)
at sun.jvm.hotspot.tools.HeapDumper.run(HeapDumper.java:56)
at sun.jvm.hotspot.tools.Tool.start(Tool.java:221)
at sun.jvm.hotspot.tools.HeapDumper.main(HeapDumper.java:77)