WebSphere MQ 7.0.1 and 7.1.0: Client channels using a shared listener and SHARECNV>1 may experience orphaned channel status entries, causing a build-up of rows in the CSQ.ADMIN_B_SCST table in DB2

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Abstract

A WebSphere MQ (WMQ) Client using shared conversations connects to the queue manager through the shared listener (INDISP(GROUP)). An entry (row) is added into the shared channel status table CSQ.ADMIN_B_SCST. The shared status entry will be orphaned (not deleted) if the last conversation to end is not the first conversation started, when SHARECNV is greater than 1 on the SVRCONN definition.
The problem will be fixed by PM81116. The following details the steps required to avoid the problem and to cleanup the orphaned rows.

Content

Reported symptoms have included:

  • Delayed responses when trying to do a STOP CHANNEL or DISPLAY CHSTATUS for a SVRCONN channel.
  • Displayed response when displaying the channels using the ISPF panels ('List Channels'), and the count of channels given in the Active column is higher than expected.
  • High CPU in the CHIN and MSTR address spaces.
  • A high count for the number of channel status in response to a DISPLAY CHSTATUS(..) SHORT command, e.g.
    CSQN205I COUNT= 149862, RETURN=00000000, REASON=00000000

    or the CSQOLCAA List Channels panel has a status with a high number such as
    149862 RUN
  • CSQX489E CSQXRESP Maximum instance limit 50 exceeded because the stop of the current channels is taking so long to complete


To prevent orphaned status entries, do one of the following:


Until the fix can be applied, circumventions include:


Clean up the orphaned status entries.

The work-arounds above will not clean up entries that were already orphaned. The options below will take a while depending on how many rows there are:

  • Restart the CHIN.
    Deletion of the orphaned entries will take place while the CHIN is terminating, so there may be a delay before it can be started again.
  • Run a SPUFI command:
    DELETE FROM CSQ.ADMIN_B_SCST WHERE CHLNAME='<channelname>'
    AND QSGNAME='<qsgname>';
    where <channelname> and <qsgname> are replaced as appropriate for your system.

    There might be contention for the table.

    You will get CSQX485E "Shared channel status error" and an FFST if a client ends after its entry has been deleted. These will not be a big impact, if there are not too many active clients at the time.
  • Delete and redefine the SVRCONN channel.
    This option will have more overhead than the SPUFI option due to the involvement of the MSTR and CHIN jobs in doing the clean-up.

Product Alias/Synonym

WMQ MQ

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Document information


More support for:

WebSphere MQ
Shared Channels

Software version:

7.0.1, 7.1

Operating system(s):

z/OS

Reference #:

1625877

Modified date:

2013-05-28

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