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IT24124: FOR MQ FOR NONSTOP ON ITANIUM 5.3.1, EC REPEATEDLY RESTARTS CERTAIN CHILD PROCESS (LQMA).

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APAR status

  • Closed as program error.

Error description

  • EC repeatedly restarts certain child process (LQMA) which lead
    to high CPU usage. The EC gets into a loop and spawns new LQMAs
    trying a process name that is already in use. This is a
    situation the EC is not prepared to handle as keeping a list of
    free numbers and this number is part of the free list. EC is
    unable to find a way out of this loop as long as the process
    name stays is in use. This process spawn loop produces a lot of
    load on the system.
    This APAR is working on an EC enhancement to bypass a process
    name if a process start fails because of a name conflict.
    

Local fix

  • The customer should make sure there are no processes matching
    the agent process name rule. If it happens, the customer could
    check if the process using the conflicting process name can be
    stopped and restarted with a different process name. However,
    stopping the process does not always resolve the problem.
    If the execution controller continues to create processes,
    the CPU usage will remain high. If that happens,
    the customer needs to restart the Queuemanager.
    

Problem summary

  •  Root cause is a wrong error handling inside the
    EC in the case of a failed process start. The EC receives EAGAIN
    and _TPC_BADNAME_FERROR on process completion and tries the same
    name again.
    

Problem conclusion

  •  The error handling in the case of an agent
    process creation failure has been modified. A process name that
    just caused a bad name error will not be used on the next
    attempt.
    

Temporary fix

  •  Don't use process names for non-MQ processes that
    matches the naming rule defined by the user in qmproc.ini.
    

Comments

APAR Information

  • APAR number

    IT24124

  • Reported component name

    WEBS MQ NSS ITA

  • Reported component ID

    5724A3902

  • Reported release

    531

  • Status

    CLOSED PER

  • PE

    NoPE

  • HIPER

    NoHIPER

  • Special Attention

    NoSpecatt / Xsystem

  • Submitted date

    2018-02-20

  • Closed date

    2018-03-02

  • Last modified date

    2020-10-14

  • 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

    WEBS MQ NSS ITA

  • Fixed component ID

    5724A3902

Applicable component levels

[{"Line of Business":{"code":"LOB36","label":"IBM Automation"},"Business Unit":{"code":"BU053","label":"Cloud & Data Platform"},"Product":{"code":"SSFKSJ","label":"WebSphere MQ"},"Platform":[{"code":"PF025","label":"Platform Independent"}],"Version":"5.3.1"}]

Document Information

Modified date:
15 October 2020