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MF62223 - LIC-DB-OTHER-WAIT Queries may hang during optimization

PTF ( Program Temporary Fixes ) Cover letter


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Abstract

LIC-DB-OTHER-WAIT Queries may hang during optimization


Pre/Co-Requisite PTF / Fix List

REQ  LICENSED           PTF/FIX  LEVEL

TYPE PROGRAM  RELEASE   NUMBER   MIN/MAX  OPTION
---- -------- --------- -------  -------  ------
CO   5770999  V7R3M0    MF61396   00/00    0000
CO   5770999  V7R3M0    MF61181   00/00    0000
CO   5770999  V7R3M0    MF61180   00/00    0000



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APAR Error Description / Circumvention

-----------------------------------------------
Multiple jobs may hang simultaneously while performing query
optimization. The call stack for each job will show LIC module
entries for DbKeyRangeCache near the top of the stack. The call
stack for one job will include the LIC module SkRefCount.

CORRECTION FOR APAR MA45709 :
-----------------------------
A race condition between three jobs obtaining an identical key
range estimate from the same index may produce a deadlock. The
deadlock is due to contention on a single entry in the key range
estimate cache. The deadlock will also block any other job
seeking to access the key range estimate cache.  This fix
improves how the cache arbitrates requests during the race
condition and eliminates the cause of the deadlock.

CIRCUMVENTION FOR APAR MA45709 :
--------------------------------
The job having SkRefCount in its call stack may be canceled.
Once this is done, the other jobs will resume normal operation.


Activation Instructions


None.




Special Instructions


None.


Default Instructions

THIS PTF CAN BE APPLIED IMMEDIATE OR DELAYED.



Supersedes

PTF/FIX NO(S).  APAR TITLE LINE
--------------  ------------------------------------------------------------
   MF61949      LIC-DB-OTHER-UNPRED Internal Database Maintenance
   MF61395      LIC-DB-OTHER Internal database maintenance
   MF61179      LIC-DB-OTHER Enable key range estimate operations to return

Summary Information

System.............................. i
Models..............................
Release............................. V7R3M0
Licensed Program............... 5770999
APAR Fixed.......................... View details for APAR MA45709
Superseded by:...................... View fix details for PTF MF65604
Recompile........................... N
Library............................. QSYS
MRI Feature ........................ NONE
Cum Level........................... C6299730


System i Support

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Document information

More support for: i family

Software version: V7R3M0

Operating system(s): OS/400

Reference #: MF62223

Modified date: 06 July 2016