JDK-6999491 : non-zero COOPs are used when they should not
  • Type: Bug
  • Component: hotspot
  • Sub-Component: runtime
  • Affected Version: hs19,hs20
  • Priority: P3
  • Status: Closed
  • Resolution: Fixed
  • OS: generic
  • CPU: generic
  • Submitted: 2010-11-12
  • Updated: 2012-10-01
  • Resolved: 2011-04-23
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JDK 6 JDK 7 Other
6u25Fixed 7Fixed hs20Fixed
Related Reports
Duplicate :  
JDK-7006429 - COOPs crashes when heap PermSize is too large
Relates :  
JDK-6984368 - Large default heap size does not allow to use zero based compressed oops.
Description
Running with "-Xmx35g -XX:HeapBaseMinAddress=32g" leads to COOPs used.
However, virtual space address limit exceeds 32g, so no COOPs should be used. 
ObjectAlignmentInBytes is equal to 8 in this case.
Comments
EVALUATION http://hg.openjdk.java.net/jdk7/build/hotspot/rev/0ac62b4d6507
25-12-2010
PUBLIC COMMENTS Regression introduced by fix for 6984368 bug. The expression in max_heap_for_compressed_oops() produces incorrect result when HeapBaseMinAddress > OopEncodingHeapMax. HeapBaseMinAddress should be used only for a default heap size calculation. Added heap size to PrintCompressedOopsMode output.
12-11-2010
EVALUATION http://hg.openjdk.java.net/jdk7/hotspot-comp/hotspot/rev/0ac62b4d6507
12-11-2010
EVALUATION Regression introduced by fix for next bug 6984368: Large default heap size does not allow to use zero based compressed oops The next expression result is negative with such options and it will return huge unsigned value inline uintx max_heap_for_compressed_oops() { // Heap should be above HeapBaseMinAddress to get zero based compressed oops. LP64_ONLY(return OopEncodingHeapMax - MaxPermSize - os::vm_page_size() - HeapBaseMinAddress); so the next condition will be always true if (MaxHeapSize <= max_heap_for_compressed_oops()) {
12-11-2010