A fix is available
APAR status
Closed as program error.
Error description
The customer is running WebSphere MQ V7.1 in a 5-way QSG when receive: . CSQV086E +CSQ1 QUEUE MANAGER ABNORMAL TERMINATION REASON=00E50702 IEA794I SVC DUMP HAS CAPTURED: DUMPID=018 REQUESTED BY JOB (CSQ1MSTR) DUMP TITLE=CSQ1,ABN=0C4-00000011,U=SYSOPR ,C=R3600.710.CFM -CSQERCAT,M=CSQGFRCV,LOC=CSQELPLM.CSQERCAT+00000890 IEF450I CSQ1MSTR CSQ1MSTR - ABEND=S6C6 U0000 REASON=00E50702 . The change team has taken a look at the dump for the 0C4 in CSQERCAT. It is due to an error in the handling of the IVSA object used in a request to refresh the local representation of a shared queue after an update. . An alter was made to queue SHR_QUEUE significant enough to trigger messages to all QMGRs in the QSG to request them to update their local representation of the queue. To do this update, CSQMELTRX calls CSQMLTRX, which schedules an asynchronous request to CSQMLTR0 to do the update. CSQMLTR0 calls CSQMREF1 to do the processing. CSQMREF1 is getting the IVSA latch for the queue, and as it is held, is suspended for 2 seconds in this case. . While being suspended, the queue is deleted on CSQ8, causing the IVSA on CSQ9 to be released. By the time CSQMREF1 is resumed (after obtaining the latch), the IVSA has been reallocated to a local queue. This causes some unexpected data in some of the IVSA fields. When using it, the 0C4 abend occurs. . The root cause seems to be missing synchronisation, allowing the queue to be deleted whilst we are attempting to update its local representation.
Local fix
Problem summary
**************************************************************** * USERS AFFECTED: All users of Websphere MQ for z/OS Version 7 * * Release 1 Modification 0. * **************************************************************** * PROBLEM DESCRIPTION: Alteration and subsequent deletion of a * * shared queue, and new queues being * * defined on another queue manager in the * * same queue sharing group may cause a * * 0C4 abend with reason 00000011. * **************************************************************** * RECOMMENDATION: * **************************************************************** When a shared queue is being altered by one queue manager in a QSG, a request will be propagated throughout the QSG instructing other queue managers to update their local representation of the shared queue object. While this process is ongoing, if another member of the QSG happens to delete the same shared queue there is a timing window where the IVSA control block representing the original queue may be deleted and even reused by another queue. When the request to propagate the original alter command completes, the queue manager may still be using the IVSA that has been removed and subsequently reallocated. This leads to the S0C4 abend occurring when attempting to use the now-incorrect IVSA block.
Problem conclusion
The alter processing has been amended to flag the local representation of the queue for the duration of the operation. This flag restricts the ability to delete the local queue representation while on. This ensures the object is still valid for the entire duration of the processing. 100Y CSQELTRX CSQICDSQ CSQMLTR0
Temporary fix
********* * HIPER * *********
Comments
APAR Information
APAR number
PM78129
Reported component name
WMQ Z/OS V7
Reported component ID
5655R3600
Reported release
100
Status
CLOSED PER
PE
NoPE
HIPER
YesHIPER
Special Attention
NoSpecatt / Xsystem
Submitted date
2012-11-29
Closed date
2013-02-13
Last modified date
2013-03-04
APAR is sysrouted FROM one or more of the following:
APAR is sysrouted TO one or more of the following:
UK91135
Modules/Macros
CSQELTRX CSQICDSQ CSQMLTR0
Fix information
Fixed component name
WMQ Z/OS V7
Fixed component ID
5655R3600
Applicable component levels
R100 PSY UK91135
UP13/03/01 P F302
Fix is available
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Document Information
Modified date:
04 March 2013