IJ21009: INCREASED RESPONSE TIME AND HIGH CPU UNDER BALANCED GC POLICY

APAR status

• Closed as program error.

Error description

• Error Message: Global Marking Phase is running much more
  frequently, almost running back to back, it causes high CPU
  usage and lower performance
  .
  Stack Trace: N/A
  .
  <gc-op id="58218" type="copy forward" timems="180.606"
  contextid="58214" timestamp="2019-11-11T12:53:53.114">
  ...
    <references type="soft" candidates="21757" cleared="0"
  enqueued="0" dynamicThreshold="12" maxThreshold="32" />
    <references type="weak" candidates="1865" cleared="0"
  enqueued="0" />
  ...
  </gc-op>
  none of references have been cleared during gc-op copyforward
  

Local fix

• this issue can be worked around using -Xgcpolicy:gencon option
  

Problem summary

• missing to clear soft/weak reference during copyforward
  increases live bytes promotion and causes the more frequent
  Global Marking Phase cycles
  

Problem conclusion

• The JVM has been updated to clear the reference correctly during
  copyforward
  .
  This APAR will be fixed in the following Java Releases:
     8    SR6 FP5   (8.0.6.5)
  .
  Contact your IBM Product's Service Team for these Service
  Refreshes and Fix Packs.
  For those running stand-alone, information about the available
  Service Refreshes and Fix Packs can be found at:
             https://www.ibm.com/developerworks/java/jdk/
  

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

• R270 PSY

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