IJ07755: SOCKET COMMUNICATION OVER NIO IN AIX CAUSES HIGH CPU EVEN THOUGH THE CONNECTION IS IDLE.

APAR status

• Closed as program error.

Error description

• Error Message: N/A
  .
  Stack Trace: The high cpu threads hold the following stack.
  at sun/misc/Unsafe.park(Native Method)
  at
  java/util/concurrent/locks/LockSupport.park(LockSupport.java:198
  (Compiled Code))
  at
  java/util/concurrent/locks/AbstractQueuedSynchronizer$ConditionO
  bject.await(AbstractQueuedSynchronizer.java:2055(Compiled Code))
  
  at
  java/util/concurrent/ArrayBlockingQueue.take(ArrayBlockingQueue.
  java:386(Compiled Code))
  
  at
  sun/nio/ch/UnixEventPort$EventHandlerTask.run(UnixEventPort.java
  :277(Compiled Code))
  
  at
  sun/nio/ch/AsynchronousChannelGroupImpl$1.run(AsynchronousChanne
  lGroupImpl.java:125)
  
  at
  java/util/concurrent/ThreadPoolExecutor.runWorker(ThreadPoolExec
  utor.java:1157(Compiled Code))
  
  at
  java/util/concurrent/ThreadPoolExecutor$Worker.run(ThreadPoolExe
  cutor.java:627)
  
  at java/lang/Thread.run(Thread.java:809)
  .
  

Local fix

Problem summary

• The problem is caused due to a bug in the poll mechanism which
  keeps returning the same event registered again and again until
  it is processed. Due to this the worker threads are interrupted
  with nothing to process, resulting in increased cpu usage.
  

Problem conclusion

• The JVM has been updated to reset the event in the events list
  when ever it is returned.
  .
  This APAR will be fixed in the following Java Releases:
     8    SR5 FP20  (8.0.5.20)
     7 R1 SR4 FP30  (7.1.4.30)
     7    SR10 FP30 (7.0.10.30)
  .
  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

  JAVA CLASS LIBS

• Fixed component ID

  620700130

Applicable component levels

• R800 PSY

     UP

• R700 PSY

     UP