IJ06892: INCREASED PERFORMANCE IMPACT AFTER CLASS REDEFINITION

APAR status

• Closed as program error.

Error description

• Error Message: Under some circumstances customers using a Java
  agent that performs class redefinition may experience a larger
  performance impact with Java 8 SR5 than with earlier releases.
  .
  Stack Trace: N/A
  .
  

Local fix

• The problem can be avoided by using the following option:
  -Xjit:disableNextGenHCR
  Note that there can only be a single -Xjit option on the command
  line, and if necessary multiple options can be combined using
  commas.
  

Problem summary

• When a class is redefined, a JIT-compiled method inlining the
  redefined callees transfers from the JIT-compiled code to the
  interpreted code to avoid executing a stale version of the
  redefined callee. The issue is caused by doing the transition
  everytime the caller method is invoked.
  

Problem conclusion

• The JIT-Compiler has been updated to recompile the method the
  first time it transits from the JIT-compiled code to the
  interpreted code to avoid doing the transition repeatedly.
  .
  This APAR will be fixed in the following Java Releases:
   8 SR5 FP17 (8.0.5.17)
  .
  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:

• Fixed component name

  JIT

• Fixed component ID

  620700124

Applicable component levels