A lock wait situation may occur after successful collection of
asynchronous statistics via JITS (just in time statistics).
Asynchronous statistics collection will update the statistics
cache as well as the catalog tables, for which an internal
catalog cache is held in exclusive mode.
The JITS daemon may not release this lock after a non successful
return during commit of the catalog changes.
By still holding the internal catalog cache in exclusive mode
other agents will be blocked when they attempt to look up
information from the database catalog.
APAR IT06379 provided an incomplete fix when attempt to resolve
the release the lock in such a condition
Snapshots (application/lock snapshot) will show the db2acd
process in UOW Waiting but holding an internal catalog cache
log:
Application name = db2acd
Application status = UOW Waiting
Object Type = Internal Catalog Cache Lock
In the optstats log file one will see one of the following
warnings:
2014-08-11-14.51.21.240570+120 I2637247E537 LEVEL:
Warning
PID : 5435 TID : 140251444623104 PROC :
db2acd 0
INSTANCE: aaaaaa NODE : 000 DB : bbb
APPID : *LOCAL.db2glp.140811114452
HOSTNAME: myhost
FUNCTION: DB2 UDB, Automatic Table Maintenance,
JitsDaemon::runstats, probe:70
MESSAGE : SQL10007N Message "99999" could not be retrieved.
Reason code: "4".
DATA #1 : String, 45 bytes
AutoStats: Non zero code from Runstats commit
DATA #2 : String, 10 bytes
RTS Daemon
2014-08-11-14.51.51.726682-300 I128835E561 LEVEL:
Warning
PID : 16333 TID : 140475138823936 PROC : db2acd
0
INSTANCE: aaaaaa NODE : 000 DB : bbb
APPID : *LOCAL.db2glp.140811114452
HOSTNAME: myhost
FUNCTION: DB2 UDB, Automatic Table Maintenance,
JitsDaemon::runstats, probe:60
MESSAGE : ZRC=0xFFFE7961=-99999
DATA #1 : String, 45 bytes
AutoStats: Non zero code from Runstats commit
DATA #2 : String, 10 bytes
RTS Daemon
DATA #3 : String, 36 bytes
COMMIT Failed - invoke tran rollback
2014-08-11-14.51.51.727614-300 I129397E482 LEVEL:
Warning
PID : 16333 TID : 140475138823936 PROC : db2acd
0
INSTANCE: aaaaaa NODE : 000 DB : bbb
APPID : *LOCAL.db2glp.140811114452
HOSTNAME: myhost
FUNCTION: DB2 UDB, Automatic Table Maintenance,
JitsDaemon::runstats, probe:65
MESSAGE : ZRC=0xFFFE7961=-99999
DATA #1 : String, 68 bytes
ROLLBACK Failed - issue disconnect/connect to release the locks
held |
