IT30124: Queue manager unavailable under high load. Reports AMQ6150: WebSphere MQ semaphore is busy

APAR status

• Closed as program error.

Error description

• The MQ application can not connect, receiving the "MQ is
  unavailable" error.  On the queue manager, this semaphore error
  appears every 15 minutes:
  
  AMQ6150: WebSphere MQ semaphore is busy
  

Local fix

Problem summary

• ****************************************************************
  USERS AFFECTED:
  Users connecting several thousand applications to a queue
  manager may encounter FFSTs, this is more likely to occur on the
  Windows platform due to the shared memory server.
  
  
  Platforms affected:
  MultiPlatform
  
  ****************************************************************
  PROBLEM DESCRIPTION:
  When a large number of connections are made to a queue manager,
  the primary shared memory sets that are used to track the
  connections may need to be extended. When this extension
  occurred, a new connection held a queue-manager-wide lock whilst
  the additional shared memory segments were attached. On the
  Windows platform the attach of the additional shared memory
  involved interprocess communication with the shared subpool
  server, this caused contention on the lock and generated FFSTs.
  

Problem conclusion

• The logic to attach extended shared memory sets was reworked to
  avoid lock contention.
  
  ---------------------------------------------------------------
  The fix is targeted for delivery in the following PTFs:
  
  Version    Maintenance Level
  v9.0 LTS   9.0.0.9
  v9.1 CD    9.1.5
  v9.1 LTS   9.1.0.4
  
  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 M/P

• Fixed component ID

  5724H7261

Applicable component levels