SA should be robust enough to iterate the objects. If one or more objects
are in inconsistent state or it is corrupted SA should ignore those
bad objects and continue to iterate the heap.

Here are few case stack traces where SA bails out when it finds bad data in the object.

1. Here bad Offset is passed to "isMarked()" so the SA is asserting with index out
   of bounds.


Caused by: sun.jvm.hotspot.utilities.AssertionFailure: BitMap index out of bounds
at sun.jvm.hotspot.utilities.Assert.that(Assert.java:32)
at sun.jvm.hotspot.utilities.BitMap.at(BitMap.java:44)
at sun.jvm.hotspot.memory.CMSBitMap.isMarked(CMSBitMap.java:108)
at sun.jvm.hotspot.memory.CMSCollector.blockSizeUsingPrintezisBits(CMSCollector.java:63)
at sun.jvm.hotspot.memory.CompactibleFreeListSpace.getLiveRegions(CompactibleFreeListSpace.java:116)
at sun.jvm.hotspot.oops.ObjectHeap$LiveRegionsCollector.doSpace(ObjectHeap.java:534)
at sun.jvm.hotspot.memory.ConcurrentMarkSweepGeneration.spaceIterate(ConcurrentMarkSweepGeneration.java:66)
at sun.jvm.hotspot.oops.ObjectHeap.collectLiveRegions(ObjectHeap.java:559)
at sun.jvm.hotspot.oops.ObjectHeap.iterate(ObjectHeap.java:243)
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)



2. If object has a reference to another object and that reference is a bad address then
   SA throws unmappedAddressException. SA should ignore this bad object.

Caused by: sun.jvm.hotspot.debugger.UnmappedAddressException
at sun.jvm.hotspot.debugger.PageCache.checkPage(PageCache.java:209)
at sun.jvm.hotspot.debugger.PageCache.getData(PageCache.java:63)
at sun.jvm.hotspot.debugger.DebuggerBase.readBytes(DebuggerBase.java:205)
at sun.jvm.hotspot.debugger.proc.ProcDebuggerLocal.readCInteger(ProcDebuggerLocal.java:329)
at sun.jvm.hotspot.debugger.DebuggerBase.readAddressValue(DebuggerBase.java:442)
at sun.jvm.hotspot.debugger.proc.ProcDebuggerLocal.readOopHandle(ProcDebuggerLocal.java:343)
at sun.jvm.hotspot.debugger.proc.ProcAddress.getOopHandleAt(ProcAddress.java:113)
at sun.jvm.hotspot.oops.Oop.getKlassForOopHandle(Oop.java:222)
at sun.jvm.hotspot.oops.ObjectHeap.newOop(ObjectHeap.java:364)
at sun.jvm.hotspot.memory.CompactibleFreeListSpace.getLiveRegions(CompactibleFreeListSpace.java:138)
at sun.jvm.hotspot.oops.ObjectHeap$LiveRegionsCollector.doSpace(ObjectHeap.java:534)
at sun.jvm.hotspot.memory.ConcurrentMarkSweepGeneration.spaceIterate(ConcurrentMarkSweepGeneration.java:66)
at sun.jvm.hotspot.oops.ObjectHeap.collectLiveRegions(ObjectHeap.java:559)
at sun.jvm.hotspot.oops.ObjectHeap.iterate(ObjectHeap.java:243)
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)
... 6 more



3. Here is another case of unmapped exception. In this case it is thrown while iterating symbolTable.

       at sun.jvm.hotspot.debugger.PageCache.checkPage(PageCache.java:208)
        at sun.jvm.hotspot.debugger.PageCache.getData(PageCache.java:63)
        at sun.jvm.hotspot.debugger.DebuggerBase.readBytes(DebuggerBase.java:205)
        at sun.jvm.hotspot.debugger.linux.LinuxDebuggerLocal.readCInteger(LinuxDebuggerLocal.java:471)
        at sun.jvm.hotspot.debugger.DebuggerBase.readAddressValue(DebuggerBase.java:442)
        at sun.jvm.hotspot.debugger.linux.LinuxDebuggerLocal.readOopHandle(LinuxDebuggerLocal.java:431)
        at sun.jvm.hotspot.debugger.linux.LinuxAddress.getOopHandleAt(LinuxAddress.java:115)
        at sun.jvm.hotspot.oops.Oop.getKlassForOopHandle(Oop.java:222)
        at sun.jvm.hotspot.oops.ObjectHeap.newOop(ObjectHeap.java:348)
        at sun.jvm.hotspot.utilities.HashtableEntry.literal(HashtableEntry.java:53)
        at sun.jvm.hotspot.memory.SymbolTable.symbolsDo(SymbolTable.java:106)
        at sun.jvm.hotspot.utilities.HeapHprofBinWriter.writeSymbols(HeapHprofBinWriter.java:830)
        at sun.jvm.hotspot.utilities.HeapHprofBinWriter.write(HeapHprofBinWriter.java:396)
        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)