A fix is available
APAR status
Closed as program error.
Error description
Hursley finds this problem occurs when the non-persistent scavenger removes an empty page from the queue's page chain, and tells the deferred write processor to bypass writing any updates to the page to the pageset on the basis that the page can no longer be referred to by any putters or getters. Ordinarily this is true, however when using get by message token the record is located directly rather than via the page chain. If the buffer containing the deallocated spine page has been stolen, an unexpected reference to the page via the message token causes the old page contents to be read from the pageset, leading to the reported symptoms.
Local fix
n/a
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: Unpredictable behaviour occurs when * * MQGET is called to get a deleted * * non-persistent message, matching on * * MsgToken, if the page containing the * * message is no longer part of the page * * chain. * * Symptoms can include: * * Abend 5C6-00C90D06 in CSQIMGE9 * * Abend 5C6-00C93100 in CSQIMGE1 * * MQGET returning a deleted message * **************************************************************** After the last message on a page was deleted, the non-persistent page scavenger removed the page from the queue's page chain. As the page contents could no longer be located and referenced via the page chain, any updates to the page were not written to the page set. The buffer containing the page was stolen, due to stress on the buffer pool, and was then reread from the page set when an application attempted to locate and get the deleted message by MsgToken. As the contents had not been written out, an old copy of the page was read back in. While attempting to return the message, CSQIMGE9 detected the IRH9 record did not match the IRH8, and the abend occurred.
Problem conclusion
The non-persistent page scavenger is changed to release deallocated pages without bypassing writing out the contents of the page.
Temporary fix
Comments
APAR Information
APAR number
PH16269
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
2019-08-30
Closed date
2019-09-25
Last modified date
2019-11-01
APAR is sysrouted FROM one or more of the following:
APAR is sysrouted TO one or more of the following:
PH16323 UI65491 UI65492
Modules/Macros
CSQISCN3 CSQISCN4 CSQISCN5
Fix information
Fixed component name
IBM MQ Z/OS V9
Fixed component ID
5655MQ900
Applicable component levels
Fix is available
Select the PTF appropriate for your component level. You will be required to sign in. Distribution on physical media is not available in all countries.
[{"Business Unit":{"code":"BU053","label":"Cloud & Data Platform"},"Product":{"code":"SSYHRD","label":"IBM MQ"},"Component":"","ARM Category":[],"Platform":[{"code":"PF025","label":"Platform Independent"}],"Version":"9.0","Edition":"","Line of Business":{"code":"LOB45","label":"Automation"}}]
Document Information
Modified date:
01 November 2019