IV53455: EXCESSIVE TIME SPENT IN JIT COMPILATION OF JSP METHODS

APAR status

• Closed as program error.

Error description

• Error Message: The JIT compilation thread in Java 6 is observed
  to consume a large amount of CPU time.
  .
  Stack Trace: N/A
  .
  If verbose JIT output is enabled, messages like the one below
  may appear numerous times in the verbose JIT log:
  !
  com/ibm/_jsp/_applicationClass._jspService(Ljavax/servlet/http/H
  ttpServletRequest;Ljavax/servlet/http/HttpServletResponse;)V
  code=0xFFFFFFFC compilationMaxCallerIndexExceeded
  

Local fix

• This issue can be avoided by setting the JVM option
  -Xjit:disableLookahead.
  

Problem summary

• The problem is caused by the class lookahead analysis performed
  by the JIT compiler. If a class contains a large number of
  methods, this analysis can take a long time to complete. In
  addition, the analysis can sometimes overflow an internal data
  limit, forcing the JIT compiler to abort and retry the
  compilation, which costs even more time.
  

Problem conclusion

• This defect will be fixed in:
  6.0.0 SR16
  6.0.1 SR5
  .
  The JIT compiler has been updated to reduce the impact of class
  lookahead analysis.
  

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

• R600 PSY

     UP