IBM Support

SI46804 - IPL-SRCC9002910-LOOP Loop sending message

PTF Cover Letter


PTF ( Program Temporary Fixes ) Cover letter


Order this fix

Abstract

IPL-SRCC9002910-LOOP Loop sending message


Pre/Co-Requisite PTF / Fix List

REQ  LICENSED      PTF/FIX  LEVEL

TYPE PROGRAM  REL  NUMBER   MIN/MAX  OPTION
---- -------- ---  -------  -------  ------
NONE



NOTICE:
-------
Application of this PTF may disable or render ineffective programs that
use system memory addresses not generated by the IBM translator,
including programs that circumvent control technology designed to limit
interactive capacity to purchased levels.  This PTF may be a prerequisite
for future PTFs.  By applying this PTF you authorize and agree to the
foregoing.

This PTF is subject to the terms of the license agreement which
accompanied, or was contained in, the Program for which you are obtaining
the PTF.  You are not authorized to install or use the PTF except as part
of a Program for which you have a valid Proof of Entitlement.

SUBJECT TO ANY WARRANTIES WHICH CAN NOT BE EXCLUDED OR EXCEPT AS EXPLICITLY
AGREED TO IN THE APPLICABLE LICENSE AGREEMENT OR AN APPLICABLE SUPPORT
AGREEMENT, IBM MAKES NO WARRANTIES OR CONDITIONS EITHER EXPRESS OR IMPLIED,
INCLUDING BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OR CONDITIONS OF
MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE, AND NON INFRINGEMENT,
REGARDING THE PTF.

The applicable license agreement may have been provided to you in printed
form and/or may be viewed using the Work with Software Agreements (WRKSFWAGR)
CL command.





APAR Error Description / Circumvention

-----------------------------------------------
A job will go into a loop while sending a message to a
nonprogram message queue, like QHST or QSYSOPR. It does not
affect messages sent to a job log or program message queue.
Frequently, the problem occurs after a system crash, forced IPL,
or use of flash copy support. During the IPL after one of those
functions, the SCPF job will go into a loop while sending a
message. Usually, program QMHSNSTQ appears in the stack as the
program that is looping. One symptom was the target of warm
flash copy function stays at SRC C9002910 for hours. A different
customer system went into a loop sending a message to a user
profile message queue, which also involved QMHSNSTQ looping, but
it did not occur during an IPL.

These functions, system crash, forced IPL and use of flash copy,
result in the loss of data in memory, so it appears as if
QSYSOPR was interrupted in the middle of adding a message to the
message queue. It is similar to a system losing power without
Uninterruptable Power Supply (UPS) protection which could cause
the data in memory to not be written to disk. With flash copy,
QSYSOPR message queue was being used during the first IPL after
the flash copy when the loop was noticed. A Main Store Dump was
taken and step mode IPL was started. When the DST signon screen
appeared, service damaged the QSYSOPR message queue to continue
the IPL. This APAR is being opened to see if there is a way to
enhance QSYSOPR recovery during the IPL after losing memory.

CORRECTION FOR APAR SE51961 :
-----------------------------
The message queue being used during the loop had logical damage
or corruption. For example, a message chain would be corrupt
when a message entry points to a wrong location. The corruption
can occur when the updating of a message queue is interrupted in
the middle of making a change. The system is designed to detect
several types of message queue corruption or damage, and would
force an MSGMCH0601 to cause message queue cleanup to occur. The
loop occurred because the message queue cleanup was not getting
invoked as expected. This was caused by a change in low-level
system function that no longer produced an error as it did in
the past. This fix is making a change to the method used to
force the MCH0601, so the message queue cleanup will once again
be called as expected when logical damage or corruption is
detected.

This fixes message handling send operations that are sending
messages to a nonprogram message queue. The fix will not prevent
message queue logical damage or corruption from occurring. It
only forces the MCH0601 to be generated, so the cleanup program
can be invoked as it was in the past, before the low-level
system change was made to eliminate the error.

CIRCUMVENTION FOR APAR SE51961 :
--------------------------------
None.


Activation Instructions


None.




Special Instructions


None.


Default Instructions

THIS PTF CAN BE APPLIED IMMEDIATE OR DELAYED.



Supersedes

PTF/FIX NO(S).  APAR TITLE LINE
--------------  ------------------------------------------------------------
   SI44308      OSP-OTHER-T/QMHSNINQ-MSGMCH0602 Message queue corrupted
   SI43217      OSP-OTHER JOB NEEDS TO BE ENDED ABNORMALLY
   SI38578      OSP-MSGCPF2438 MSGCPF2438 intermittently issued incorrectly
   SI37788      OSP Wrong message information in watch for event support

Summary Information

System..............................i
Models..............................
Release.............................V7R1M0
Licensed Program...............5770SS1
APAR Fixed..........................View details for APAR SE51961
Superseded by:......................View fix details for PTF SI62025
Recompile...........................N
Library.............................QSYS
MRI Feature ........................NONE
Cum Level...........................C2279710


System i Support

IBM disclaims all warranties, whether express or implied, including, but not limited to, the implied warranties of merchantability and fitness for a particular purpose. By furnishing this document, IBM grants no licenses to any related patents or copyrights. Copyright © 1996,1997,1998, 1999, 2000, 2001, 2002, 2003, 2004, 2005, 2006, 2007, 2008, 2009, 2010, 2011, 2012, 2013, 2014, 2015, 2016, 2017 IBM Corporation. Any trademarks and product or brand names referenced in this document are the property of their respective owners. Consult the Terms of use link for trademark information.

[{"Business Unit":{"code":"BU054","label":"Systems w\/TPS"},"Product":{"code":"SG15V","label":"PTF Cover Letters - OS\/400 General"},"Component":"","ARM Category":[],"Platform":[{"code":"PF012","label":"IBM i"}],"Version":"V7R1M0","Edition":"","Line of Business":{"code":"","label":""}},{"Business Unit":{"code":"BU054","label":"Systems w\/TPS"},"Product":{"code":"SG16D","label":"PTF Cover Letters - IBM i 7.1 environment"},"Component":"","ARM Category":[],"Platform":[{"code":"PF012","label":"IBM i"}],"Version":"V7R1M0","Edition":"","Line of Business":{"code":"","label":""}}]

Document Information

Modified date:
11 May 2012