Database Hang on 12c with 'Cursor: Pin S wait on X', 'Row Cache Lock' and 'Library Cache Load Lock'
Last updated on JANUARY 31, 2018
Applies to:Oracle Database - Enterprise Edition - Version 220.127.116.11 to 18.104.22.168 [Release 12.1]
Information in this document applies to any platform.
Database hangs periodically with many sessions being blocked by each other, deadlocks can be seen as well, with different waits such as 'cursor: pin S wait on X', 'row cache lock' and 'library cache load lock'.
'Row cache lock' can be on different dictionary cache areas. In this case, they were on dc_objects and dc_histogram_defs.
Looking at the blocker processes in system state dumps we can see the function kkecIsCPUTimeReliable in their call stack.
PARALLEL_DEGREE_POLICY must be set to ADAPTIVE to run into this bug.
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