Excess Shared Pool Memory Use / ORA-4031 Due To Large "KTC Latch Subh" Allocation and Dequeues (Doc ID 2281917.1)

Last updated on JUNE 29, 2017

Applies to:

Oracle Database - Enterprise Edition - Version 11.2.0.4 and later
Information in this document applies to any platform.

Symptoms

Errors reported in the alert log:

ORA-04031: unable to allocate 544 bytes of shared memory ("shared pool","unknown object","sga heap(3,1)","KGLHD")
ORA-04031: unable to allocate 192 bytes of shared memory ("shared pool","unknown object","KTC latch subh","KTCCC OBJECT")

Or unusually large allocations to "KTC latch subh" shown in the shared pool:

TOP 20 MEMORY USES ACROSS SGA HEAP 1 - 6
----------------------------------------------
"KTC latch subh " 2940 MB 64%
"free memory " 1045 MB 23%
"SQLA " 69 MB 1%
"KWQDL deq log " 67 MB 1%

Also, increases in "KTC latch subh" can be seen following usage of DBMS_AQ.DEQUEUE.

Patch for Bug 18850278 does not provide relief.

Cause

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