IV48122: GARBAGE COLLECTION SCAN TIME FOR OWNABLESYNCHRONIZER OBJECTS IS EXCESSIVE

APAR status

• Closed as program error.

Error description

• Error Message: N/A
  .
  Stack Trace: N/A
  .
  Verbose gc log will display mark time for global garbage
  collection cycles. Mark times may be quite high if there is a
  large number of ownableSynchronizer objects to scan. For
  example:
  <gc-op id="16409" type="mark" timems="943.602" contextid="16383"
  timestamp="2013-08-26T12:37:28.838">
    <trace-info objectcount="568592" scancount="529520"
  scanbytes="17031384" />
    <finalization candidates="74580" enqueued="37130" />
    <ownableSynchronizers candidates="3386222" cleared="361251" />
    <references type="soft" candidates="11882" cleared="0"
  enqueued="0" dynamicThreshold="15" maxThreshold="32" />
    <references type="weak" candidates="296775" cleared="115367"
  enqueued="115367" />
    <references type="phantom" candidates="532" cleared="0"
  enqueued="0" />
    <stringconstants candidates="1242969" cleared="663393"  />
  </gc-op>
  

Local fix

Problem summary

• Some recent garbage collection enhancements (introduced in Java
  7 SR3 and Java 626 SR4) added the tracing of ownableSynchronizer
  objects. The original implementation has shown to have the
  potential to significantly increase global garbage collection
  time.
  

Problem conclusion

• This defect will be fixed in:
  7.0.0 SR6
  6.0.1 SR7
  .
  The implementation of tracing ownableSynchronizer objects has
  been modified to run much more efficiently.
  

Temporary fix

Comments

APAR Information

• APAR is sysrouted FROM one or more of the following:

• APAR is sysrouted TO one or more of the following:

Fix information

• Fixed component name

  J9 COMMON CODE

• Fixed component ID

  620700127

Applicable component levels

• R260 PSY

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