JDK-6868051 : (SA) FreeChunk support for compressed oops is broken
  • Type: Bug
  • Component: hotspot
  • Sub-Component: svc
  • Affected Version: hs16
  • Priority: P3
  • Status: Closed
  • Resolution: Fixed
  • OS: solaris_9
  • CPU: sparc
  • Submitted: 2009-08-03
  • Updated: 2010-04-02
  • Resolved: 2010-01-15
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JDK 6 JDK 7 Other
6u18Fixed 7Fixed hs16Fixed
Description
The code for parsing FreeChunks when compressed oops is enabled is broken.  It's got the wrong level of indirection so it will always throw an exception.

Error: sun.jvm.hotspot.debugger.UnalignedAddressException: Trying to read at address: 0x0000000000000001 with alignment: 8
sun.jvm.hotspot.debugger.UnalignedAddressException: Trying to read at address: 0x0000000000000001 with alignment: 8   
        at sun.jvm.hotspot.debugger.DebuggerUtilities.checkAlignment(DebuggerUtilities.java:57)
        at sun.jvm.hotspot.debugger.proc.ProcDebuggerLocal.readCInteger(ProcDebuggerLocal.java:316)
        at sun.jvm.hotspot.debugger.proc.ProcAddress.getCIntegerAt(ProcAddress.java:68)
        at sun.jvm.hotspot.types.basic.BasicField.getCInteger(BasicField.java:162)
        at sun.jvm.hotspot.types.basic.BasicCIntegerField.getValue(BasicCIntegerField.java:54)
        at sun.jvm.hotspot.oops.Mark.value(Mark.java:138)
        at sun.jvm.hotspot.oops.Mark.isUnlocked(Mark.java:172)
        at sun.jvm.hotspot.oops.Mark.isCmsFreeChunk(Mark.java:306)
        at sun.jvm.hotspot.memory.FreeChunk.isFree(FreeChunk.java:87)
        at sun.jvm.hotspot.memory.FreeChunk.indicatesFreeChunk(FreeChunk.java:81)
        at sun.jvm.hotspot.memory.CompactibleFreeListSpace.getLiveRegions(CompactibleFreeListSpace.java:192)
        at sun.jvm.hotspot.oops.ObjectHeap$LiveRegionsCollector.doSpace(ObjectHeap.java:554)
        at sun.jvm.hotspot.memory.ConcurrentMarkSweepGeneration.spaceIterate(ConcurrentMarkSweepGeneration.java:66)   
        at sun.jvm.hotspot.oops.ObjectHeap.collectLiveRegions(ObjectHeap.java:579)
        at sun.jvm.hotspot.oops.ObjectHeap.iterateRaw(ObjectHeap.java:284)
        at sun.jvm.hotspot.CommandProcessor$26.doit(CommandProcessor.java:897)
        at sun.jvm.hotspot.CommandProcessor.executeCommand(CommandProcessor.java:1265)
        at sun.jvm.hotspot.CommandProcessor.executeCommand(CommandProcessor.java:1235)
        at sun.jvm.hotspot.CommandProcessor.run(CommandProcessor.java:1138)
        at sun.jvm.hotspot.CLHSDB.run(CLHSDB.java:91)
        at sun.jvm.hotspot.CLHSDB.main(CLHSDB.java:35)
Comments
EVALUATION http://hg.openjdk.java.net/jdk7/hotspot-gc/hotspot/rev/ef671fb22f73
10-08-2009
EVALUATION http://hg.openjdk.java.net/jdk7/hotspot-comp/hotspot/rev/ef671fb22f73
06-08-2009
SUGGESTED FIX diff --git a/agent/src/share/classes/sun/jvm/hotspot/memory/FreeChunk.java b/agent/src/share/classes/sun/jvm/hotspot/memory/FreeChunk.java --- a/agent/src/share/classes/sun/jvm/hotspot/memory/FreeChunk.java +++ b/agent/src/share/classes/sun/jvm/hotspot/memory/FreeChunk.java @@ -63,7 +63,7 @@ public class FreeChunk extends VMObject public long size() { if (VM.getVM().isCompressedOopsEnabled()) { - Mark mark = new Mark(sizeField.getValue(addr)); + Mark mark = new Mark(addr.addOffsetTo(sizeField.getOffset())); return mark.getSize(); } else { Address size = sizeField.getValue(addr); @@ -83,7 +83,7 @@ public class FreeChunk extends VMObject public boolean isFree() { if (VM.getVM().isCompressedOopsEnabled()) { - Mark mark = new Mark(sizeField.getValue(addr)); + Mark mark = new Mark(addr.addOffsetTo(sizeField.getOffset())); return mark.isCmsFreeChunk(); } else { Address prev = prevField.getValue(addr);
03-08-2009
EVALUATION it's loading the value instead of passing the address to Mark where it will actually be loaded.
03-08-2009