IT35346: WebConsole/REST process can consume CPU if mqRestMessagingFullPoolBehavior set block.

APAR status

• Closed as program error.

Error description

• When using MQ WebConsole/REST API it is possible to see high CPU
  consumption on the MQ WebConsole/REST API process.  If there is
  a new request made, but all the pooled connection(controlled by
  mqRestMessagingMaxPoolSize) are in use and you have set
  mqRestMessagingFullPoolBehavior to block.  The new request will
  attempt to request a pool connection in a tight loop and
  increase the CPU for the process.
  

Local fix

• Increase the mqRestMessagingMaxPoolSize pool size or change
  mqRestMessagingFullPoolBehavior:
  eg.
  
  setmqweb properties -k mqRestMessagingMaxPoolSize -v size
  or
  setmqweb properties -k mqRestMessagingFullPoolBehavior -v
  <error|overflow>
  

Problem summary

• ****************************************************************
  USERS AFFECTED:
  This affects users of IBM MQ WebConsole/RestAPI.
  
  
  Platforms affected:
  MultiPlatform
  
  ****************************************************************
  PROBLEM DESCRIPTION:
  MQ WebConsole/REST API process might consume lots of CPU if
  mqRestMessagingFullPoolBehavior set to block and we have
  mqRestMessagingMaxPoolSize value active connections and
  attempting to make a new request.
  
  To optimize the performance of the messaging REST API,
  connections to IBM MQ queue managers are pooled. That is,
  instead of each REST request creating, using, and destroying its
  own connection, each REST request uses a connection from a
  connection pool.
  
  By default, 20 connections are available for each queue manager
  pool. You can change the maximum number of pooled connections
  and the default behaviour of the messaging REST API when all
  connections are in use by using the setmqweb properties command.
  
  If all of the connections in the connection pool are in use, and
  the messaging REST API has been configured to block waiting for
  an existing connection to become free, then when a new request
  comes in the messaging REST API goes into a tight loop and
  consumes lots of CPU.
  

Problem conclusion

• The code has been change to improve the behaviour and reduce the
  CPU consumption.
  
  ---------------------------------------------------------------
  The fix is targeted for delivery in the following PTFs:
  
  Version    Maintenance Level
  v9.2 LTS   9.2.0.7
  v9.x CD    9.2.2
  
  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

  MQ BASE V9.2

• Fixed component ID

  5724H7281

Applicable component levels