A fix is available
APAR status
Closed as program error.
Error description
High cpu during backup of structures, BACKUP CFSTRUCT . Loop in CSQELBK1 during BACKUP CFSTRUCT processing. Multiple CSQE121I messages.
Local fix
Problem summary
**************************************************************** * USERS AFFECTED: * * All users of IBM MQ for z/OS Version 9 Release 0 * * Modification 0. * **************************************************************** * PROBLEM DESCRIPTION: * * High CPU utilization when backing up a structure due to a * * loop in CSQELBK1 reading entries on the * * uncommitted-get-queue. * **************************************************************** * RECOMMENDATION: * * None * **************************************************************** High CPU utilization in the queue-manager after BACKUP CFSTRUCT() processing due to a loop in module CSQELBK1 reading entries on the uncommitted-get-queue. The loop occurs when two messages on the uncommitted-get-queue have the same entry key, and their combined length exceeds the buffer size passed on the call. The queue is key sequenced so the two messages are adjacent. CSQELBK1 issues an IXLLSTM REQUEST(READ_LIST) passing a 64K buffer to hold the returned messages. The first message with the duplicate key is read successfully and added to the buffer. The second message would exceed the buffer size so READ_LIST returns with reason code ixlRsnCodeBufferFull. The key of the next message to read is returned in IXL list answer area field LctlKey. CSQELBK1 processes the messages in the buffer, then re-issues the IXLLSTM REQUEST(READ_LIST) to read the next message, specifying the key returned in LctlKey. However the key of the next message is a duplicate of the message just read, so the first message is read again. When the subsequent message is processed READ_LIST again returns with ixlRsnCodeBufferFull leading to the reported indefinite loop in CSQELBK1.
Problem conclusion
CSQELBK1 has been updated for the reported problem so that IXLLSTM REQUEST(READ_LIST) locates the second duplicate key entry by it's unique entryid as well as it's key.
Temporary fix
Comments
APAR Information
APAR number
PI66136
Reported component name
MQ Z/OS V9
Reported component ID
5655MQ900
Reported release
000
Status
CLOSED PER
PE
NoPE
HIPER
YesHIPER
Special Attention
NoSpecatt / Xsystem
Submitted date
2016-07-19
Closed date
2016-10-17
Last modified date
2017-02-01
APAR is sysrouted FROM one or more of the following:
APAR is sysrouted TO one or more of the following:
UI41724
Modules/Macros
CSQELBK1
Fix information
Fixed component name
MQ Z/OS V9
Fixed component ID
5655MQ900
Applicable component levels
R000 PSY UI41724
UP17/01/10 P F701 ¢
Fix is available
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Document Information
Modified date:
01 February 2017