IT34661: MQRC 2009 ON MQINPUT NODE CAN CAUSE DELAYS IN THREAD ROLLBACK

APAR status

• Closed as program error.

Error description

• When an MQRC 2009 (MQRC_CONNECTION_BROKEN) occurs in an MQInput
  node, all the associated message flow threads will attempt to
  rollback. This rollback behaviour involves a single mutex which
  each thread must acquire in order to clean up its connection.
  This same mutex is also held while connections are
  reacquired.
  
  This can lead to a situation where some threads
  are blocked from rolling back because other threads are blocked
  in an MQCONNX call waiting for the queue manager to become
  available.
  
  This APAR refactors the locking behaviour so that
  the rollbacks can occur while other threads wait to acquire new
  connections. New connections are still acquired serially behind
  a separate mutex.
  

Local fix

• N/A
  

Problem summary

• ****************************************************************
  USERS AFFECTED:
  All users of the MQ Input node in IBM Integration Bus v10 and
  IBM App Connect Enterprise v11 or v12 connecting to remote queue
  managers.
  
  
  Platforms affected:
  z/OS, MultiPlatform
  
  ****************************************************************
  PROBLEM DESCRIPTION:
  If a remote queue manager fails without gracefully closing
  connections, and an MQInput node with a high number of
  additional instances is configured that are all waiting for
  messages, then delays occur can when recovering from the
  failover. This is caused by threads that are trying to
  re-establish their MQ connections blocking other threads from
  recovering from the connection failure.
  

Problem conclusion

• Threads recovering from the connection failure are no longer
  blocked by other threads trying to reestablish a connection to
  the queue manager.
  
  ---------------------------------------------------------------
  The fix is targeted for delivery in the following PTFs:
  
  Version    Maintenance Level
  v10.0      10.0.0.26
  v11.0      11.0.0.17
  v12.0      12.0.3.0
  
  The latest available maintenance can be obtained from:
  http://www-01.ibm.com/support/docview.wss?rs=849&uid=swg27006041
  
  If the maintenance level is not yet available,information on
  its planned availability can be found on:
  http://www-1.ibm.com/support/docview.wss?rs=849&uid=swg27006308
  ---------------------------------------------------------------
  

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

  INTEGRATION BUS

• Fixed component ID

  5724J0540

Applicable component levels