IV70546: ADDRESS LOCKING CONTENTION IN JAVA/LANG/CLASS.GETGENERICINTERFACES() AND JAVA/LANG/CLASS.GETCLASSREPOSITORY().

APAR status

• Closed as program error.

Error description

• Error Message: Performance issues may be noticed in code that
  heavily utilizes the java.lang.Class.getGenericInterface() or
  java/lang/Class.getClassRepository() methods.
  .
  Stack Trace: A javacore taken during the time of the issue will
  show multiple threads blocked on the following
  stack:4XESTACKTRACE at
  java/util/Hashtable.get(Hashtable.java: 617(Compiled
  Code))5XESTACKTRACE (entered lock:
  java/util/Hashtable@0x0000000044923FE0, entry count:
  1)4XESTACKTRACE at
  java/lang/Class.getClassRepository Class.java:2045(Compiled
  Code))4XESTACKTRACE at
  java/lang/Class.getGenericInterfaces (Class.java:2081(Compiled
  Code))
  .
  

Local fix

Problem summary

• The performance issue is due to a synchronization bottleneck in
  the implementation of java/lang/Class and java/lang/Classloader.
  

Problem conclusion

• The jvm has been updated to remove the synchronization
  bottleneck that caused the issue.
  .
  This APAR will be fixed in the following Java Releases:
   6 R1 SR8 FP4 (6.1.8.4)
   7 SR9 (7.0.9.0)
   8 SR1 (8.0.1.0)
   7 R1 SR3 (7.1.3.0)
  .
  Contact your IBM Product's Service Team for these Service
  Refreshes and Fix Packs.
  For those running stand-alone, information about the 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

• R260 PSY

     UP

• R270 PSY

     UP