IJ43736: HIGH CPU CONSUMPTION OBSERVED IN ZOSEVENTPORT$EVENTHANDLERTASK.RUN

APAR status

• Closed as program error.

Error description

• Error Message: On z/OS, high CPU consumption may be observed in
  applications using non-blocking I/O or websockets APIs, even
  while the socket connections are idle. Running the Jenkins agent
  on z/OS with "websockets" feature enabled is one scenario where
  this problem may be observed.
  .
  Stack Trace: The stack trace of the high cpu consuming threads
  may show time spent within
  sun/nio/ch/ZosEventPort$EventHandlerTask.run and its callees.
  e.g.:
  at sun/nio/ch/PollArrayWrapper.poll0(Native Method)
  at
  sun/nio/ch/PollArrayWrapper.poll(PollArrayWrapper.java:155(Compi
  led Code))
  at
  sun/nio/ch/ZosEventPort$EventHandlerTask.poll(ZosEventPort.java:
  215)
  at
  sun/nio/ch/ZosEventPort$EventHandlerTask.run(ZosEventPort.java:2
  75)
  at
  sun/nio/ch/AsynchronousChannelGroupImpl$1.run(AsynchronousChanne
  lGroupImpl.java:112)
  .
  

Local fix

Problem summary

• The problem is caused by a conservative registration of poll
  event types within ZosEventPort class. This issue may result in
  poll() calls in quick succession, causing increased cpu
  consumption.
  

Problem conclusion

• The implementation of ZosEventPort has been updated to register
  only the requested poll event types.
  .
  This APAR will be fixed in the following Releases:
  .
  IBM Semeru Runtime Certified Edition
     11              11.0.17.0
  .
  Contact your IBM Product's Service Team for these Service
  Refreshes and Fix Packs.
  For those running stand-alone, information about the available
  maintenance can be found at:
             https://www.ibm.com/support/pages/java-sdk
  

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

  OPENJDK CLASS L

• Fixed component ID

  621800100

Applicable component levels