IT38726: IBM MQ process amqzmuc0 may consume 100% CPU

APAR status

• Closed as program error.

Error description

• One thread in the amqzmuc0 process is using 100% CPU.
  
  When taking a trace the first few lines for the thread are
   -> zmuThreadMain
   -> zruResourceMonitor
  
  Elsewhere in the trace for that thread there are constantly
  repeated mentions of
  - zruAsyncInit
  - zruOpenTopics
  - zruWaitPSModeEnabled
  - MQRC_PUBSUB_INHIBITED
  
  In the recent history of FDC records in /var/mqm/errors, there
  is likely also to be KN468004 or KN468005 from
  kpiDurableSubscriptionManagerTask.
  

Local fix

• Restart the queue manager
  

Problem summary

• ****************************************************************
  USERS AFFECTED:
  Queue managers in which a severe error has occurred (example: a
  log-full condition, or damage to the queues that hold internal
  publish/subscribe state) leading to the publish/subscribe
  component being marked internally as 'failed'.
  
  This status can be determined with the MQSC command DIS PUBSUB
  ALL.  It will show STATUS(ERROR) if the publish/subscribe
  component has been marked internally as 'failed'.
  
  
  Platforms affected:
  MultiPlatform
  
  ****************************************************************
  PROBLEM DESCRIPTION:
  There is a thread in amqzmuc0 named zruResourceMonitor that is
  responsible for publishing resource usage statistics.
  
  This thread had entered a state where it was checking for the
  publish/subscribe component to become enabled.  However, the
  component was marked as 'failed' due to a previous queue manager
  failure, and in this state a small timing window existed that
  could allow the processing under zruResourceMonitor to enter a
  high CPU state where it was checking the same things constantly
  without sleeping.
  

Problem conclusion

• The IBM MQ code has been corrected so that checks are made after
  a small sleep, to avoid the timing window which could lead to
  the high CPU condition.
  
  ---------------------------------------------------------------
  The fix is targeted for delivery in the following PTFs:
  
  Version    Maintenance Level
  v9.1 LTS   9.1.0.15
  v9.2 LTS   9.2.0.10
  v9.3 LTS   9.3.0.5
  v9.x CD    9.3.2
  
  The latest available maintenance can be obtained from
  'WebSphere MQ Recommended Fixes'
  http://www-1.ibm.com/support/docview.wss?rs=171&uid=swg27006037
  
  If the maintenance level is not yet available information on
  its planned availability can be found in 'WebSphere MQ
  Planned Maintenance Release Dates'
  http://www-1.ibm.com/support/docview.wss?rs=171&uid=swg27006309
  ---------------------------------------------------------------
  

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

  IBM MQ BASE MP

• Fixed component ID

  5724H7271

Applicable component levels