DB2 UDB for z/OS Version 8 Performance Topics - IBM Redbooks

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| W A I T E R
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| R E S O U R C E
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| B L O C K E R
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| W A I T E R
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Detecting long-running readers
DB2 V8 introduces a new DSNZPARM, LRDRTHLD, as a threshold value in number of
minutes an application can hold a read claim against an object before notification. You can set
this value in order to be able to detect long-running readers. If statistics class 3 is active, an
additional field type in IFCID 313 is recorded.
4.12.3 Lock escalation IFCID 337
Many installations go to great lengths to avoid or minimize lock escalation. However, DB2 V7
does not produce an IFCID record when lock escalation occurs, thus making it difficult for
performance monitors to report on lock escalation. You can trap console message DSNI031I
today. It is produced whenever lock escalation occurs. However, performance monitors prefer
a single interface for all performance-related information through the DB2 Instrumentation
Facility Component.
DB2 V8 introduces a new IFCID 337 to report on lock escalations. IFCID 337 is added to the
statistics trace class 3 and performance trace class 6. If activated, IFCID 337 is written
whenever lock escalation occurs. The record contains a superset of the information that is
reported in message DSNI031I. Refer to Appendix C of DB2 UDB for z/OS Version 8:
Everything You Ever Wanted to Know, ... and More, SG24-6079, for a more detailed
discussion of IFCID 337, or member DSNWMGSG in DB2 V8 SDSNSAMP for a description
of its contents.
In addition, message DSNI031I is enhanced to include the collection ID in order to be
consistent with IFCID 337.
Chapter 4. DB2 subsystem performance 207