Fixes are available
APAR status
Closed as program error.
Error description
WMQ employs file locking to ensure that error messages are not "interleaved" when written. In a very rare circumstance, the locking can be briefly compromised during queue manager startup. This is highly unlikely to manifest as an actual problem, and if it does then it is limited to just causing slight interleaving of error messages.
Local fix
Problem summary
**************************************************************** USERS AFFECTED: This problem is highly unlikely to occur and there is no significant impact if it does. It should be noted that this problem was discovered on a Linux system which itself has a file locking issue that is under investigation. The WMQ issue documented here can cause interleaving of file locking and unlocking within a single process, and it is believed that this has revealed an issue in either Linux, or the controller software of the attached shared disk on which the error logs were located. This caused a WMQ hang during startup. This hang went unnoticed until qmgr shutdown, which didn't end, and resulted in a zombie amqzmur0 queue manager process. A process stack, and WMQ trace, revealed a WMQ thread waiting indefinitely for the file lock. Platforms affected: All Unix **************************************************************** PROBLEM SUMMARY: WMQ takes out a process local lock to ensure file locking operates appropriately for multiple threads writing error messages at the same time. However, WMQ V6 implements an error log "daemon" which runs in a thread parallel to various others. The error log daemon omits to make use of this process local lock during its startup when it opens the error log file, which for a brief instant can compromise the file locking.
Problem conclusion
Corrected the process local locking necessary to ensure sound use of file locking. --------------------------------------------------------------- The fix is targeted for delivery in the following PTFs: v6.0 Platform Fix Pack 6.0.2.4 -------- -------------------- AIX U814256 HP-UX (PA-RISC) U814152 HP-UX (Itanium) U814342 Solaris (SPARC) U814337 Solaris (x86-64) U814343 Linux (x86) U814336 Linux (x86-64) U814341 Linux (zSeries) U814338 Linux (Power) U814339 Linux (s390x) U814340 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
Comments
APAR Information
APAR number
IZ06672
Reported component name
WMQ LIN X86 V6
Reported component ID
5724H7204
Reported release
600
Status
CLOSED PER
PE
NoPE
HIPER
NoHIPER
Special Attention
NoSpecatt
Submitted date
2007-10-17
Closed date
2007-10-30
Last modified date
2007-10-30
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
WMQ LIN X86 V6
Fixed component ID
5724H7204
Applicable component levels
R600 PSY
UP
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Document Information
Modified date:
31 March 2023