IJ21489: JAVA JIT - PERFORMANCE REGRESSION WHEN CALLING JNI ON POWER (AIX & LINUX)

APAR status

• Closed as program error.

Error description

• Error Message: N/A
  .
  Stack Trace: N/A
  .
  Starting with Java 8.0.5.35 a performance regression was
  introduced into the POWER versions of the IBM JVM which caused
  JNI calls to sometimes be executed via the interpreter rather
  then using a more direct path from JIT code to the JNI routine.
  The problem only effects POWER machines, the issue is not
  possible on x86 or Z hardware.
  JVM versions prior to Java 8.0.5.35 do not suffer from this
  issue.
  

Local fix

• N/A
  

Problem summary

• A regression was caused by a fix for an issue where the JIT was
  assuming JNI-linkage for all call-sites using a symbol that was
  once used for a call-site that was de-virtuilized to a JNI call.
  The regression is due to the fact that this fix prevented the
  JIT from detection some cases were JNI-linkage was appropriate
  resulting in needless calls into the interpreter to initiate the
  JNI-call out sequence.
  

Problem conclusion

• The JIT was modified such that direct JIT to JNI call sequences
  are used when appropriate.
  .
  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

  JIT

• Fixed component ID

  620700124

Applicable component levels