A fix is available
APAR status
Closed as program error.
Error description
If two tasks are both browsing and retrieving messages from a queue just as the queue goes empty, it's possible for one of the tasks to complete the operation without correctly clearing its allocation locks for the page, causing the following abend to occur some later time when the page is reused: ABN= 5C6-00E7014F ,LOC=CSQXADPM.CSQXADPM Once an orphaned lock has been created, it's possible that applications using any queue on the same pageset may be impacted as the lock is held at the pageset level. This means that other applications sharing the pageset (but not the problematic queue) can also be impacted. Additional Symptom(s) Search Keyword(s): ABN= 5C6-00E7014F, ,LOC=CSQXADPM.CSQXADPM
Local fix
By no longer having multiple threads attempting to access the same pages related to a single queue, the problem should be avoided.
Problem summary
**************************************************************** * USERS AFFECTED: All users of IBM MQ for z/OS Version 9 * * Release 0 Modification 0 and Release 1 * * Modification 0. * **************************************************************** * PROBLEM DESCRIPTION: When two applications browse a shared * * queue concurrently messages may be * * left locked. * * When the record that contained the * * message is subsequently reused, abend * * 5C6-00C92200 occurs in CSQIMPU2 due * * to the orphaned lock. * **************************************************************** When two applications browse and get messages from a shared queue concurrently specific timing situations can result in the cursor.locked field within the browse cursor being reset without the associated message record lock being freed immediately. As there is now no indication that a lock is held further browse processing may not free the lock either, and it can remain set until the application ends. The residual record lock information for the message can cause subsequent processing by this or another application sharing the queue to fail if an attempt is made to put a message to the same record/page/PSID as the allocation lock appears to be already set.
Problem conclusion
Browse lock processing has been changed for the reported problem to prevent Cursor.Locked being reset invalidly.
Temporary fix
Comments
APAR Information
APAR number
PH15068
Reported component name
IBM MQ Z/OS V9
Reported component ID
5655MQ900
Reported release
000
Status
CLOSED PER
PE
NoPE
HIPER
YesHIPER
Special Attention
NoSpecatt / Xsystem
Submitted date
2019-07-30
Closed date
2019-09-05
Last modified date
2019-10-01
APAR is sysrouted FROM one or more of the following:
APAR is sysrouted TO one or more of the following:
UI65150 UI65151
Modules/Macros
CSQIMGE1 CSQIMGE3
Fix information
Fixed component name
IBM MQ Z/OS V9
Fixed component ID
5655MQ900
Applicable component levels
Fix is available
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Document Information
Modified date:
01 October 2019