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Problem IT18623
|
Status: Closed |
HIGH CONTENTION ON SQLO_LT_SQLRISECTINIT_C__DYNAMIC_XLATCH with high degree of smp parallelism when cleaning up sort operators |
| product: |
DB2 FOR LUW / DB2FORLUW / A50 - DB2 |
| Problem description: |
When INTRA_PARALLEL=YES and MAX_QUERYDEGREE=ANY the degree of
parallelism chosen by DB2 depends on available resources.
This can lead to a high degree of parallelism.
For some statements which have sorts allocated per subagent,
this can lead to a high amount of contention on the
SQLO_LT_sqlriSectInit_C__dynamic_xlatch latch whilst cleaning
up the allocated sorts.
A typical stack for the waiter would show :
sqloSpinLockConflict
sqlrsclos
sqlriclo
sqlrita
sqlriSectInvoke
This problem can mainly affect small and quick statements as the
relative impact of the inefficiency is greater. |
| Problem Summary: |
****************************************************************
* USERS AFFECTED: *
* all *
****************************************************************
* PROBLEM DESCRIPTION: *
* See Error Description *
****************************************************************
* RECOMMENDATION: *
* Upgrade to version 10.5 Fix Pack 9 *
**************************************************************** |
| Local Fix: |
manually reduce parallelism for impacted statements by either
updating the query degree value or by routing the statements to
a WLM class with a lower degree of parallelism. |
| Solution |
First fixed in version 10.5 Fix Pack 9 |
| Workaround |
not known / see Local fix |
| Timestamps |
Date - problem reported :
Date - problem closed :
Date - last modified :
| 02.01.2017
27.09.2017
27.09.2017 |
| Problem solved at the following versions (IBM BugInfos) |
9.0.
|
| Problem solved according to the fixlist(s) of the following version(s) |
