A fix is available
APAR status
Closed as program error.
Error description
When MQ has to handle a lot of process starts and terminations in a short time, due to a defect some process terminations may be missed. Unfortunately this does not lead to an FFST file, an error message in the error logs or EMS. The most likely observation is a blocking RUNMQSC process. The RUNMQSC process might have been accepted a command "ping channel..." but does not return to the prompt. The problem might show up with other process types like LISTENER or SERVICE as well.
Local fix
It's not a risk to stop the process managers as they will be restarted by MQ. If a blocking or not startable process can be observed and there is no related error log or FFST file, stopping the process managers should be considered. If there is more than one process manager running on the system, they should be stopped one by one until the block is dissolved. The process manager is amqzmgr0. This command lists the running process managers: $ ps -l | grep amqzmgr0 The kill command on OSS and stop command on TACL can be used to stop that process.
Problem summary
The root cause is an implementation error in the MQ internal process table. Due to a process table slot reuse, MQ does not handle process terminations properly and treats some already terminated processes as still being alive. This inconsistency affects new process starts and leads to RUNMQSC blocks and service start problems.
Problem conclusion
The product has been changed to fix this defect. --------------------------------------------------------------- The fix is targeted for delivery in the following PTFs: Version Maintenance Level v8.1 8.1.0.8 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
The problem has been observed in scenarios where MQSC commands have been automatically created in parallel. When each MQSC command starts a process (ping channel for instance), the process manager may have to start lots of processes and handle their process termination in a short time. Such scenarios should be avoided, once the issue showed up.
Comments
APAR Information
APAR number
IT33751
Reported component name
MQ FOR HPE NS O
Reported component ID
5724A3903
Reported release
810
Status
CLOSED PER
PE
NoPE
HIPER
NoHIPER
Special Attention
NoSpecatt / Xsystem
Submitted date
2020-07-31
Closed date
2021-06-17
Last modified date
2021-06-17
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 FOR HPE NS O
Fixed component ID
5724A3903
Applicable component levels
R810 PSY
UP
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Document Information
Modified date:
05 November 2021