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Increasing Shared Pool Buffers Due to "KJSC rnb slots" Allocation Leading to ORA-04031 Errors (Doc ID 2772028.1)

Last updated on JUNE 22, 2021

Applies to:

Oracle Database - Enterprise Edition - Version 19.1.0.0.0 and later
Information in this document applies to any platform.

Symptoms

A huge memory accumulation of KJSC Ring buffer slot is seen after upgrade to 19c leading to ORA-4031 with SGA stats showing "KJSC rnb slots" as highest consumer of the memory:

==============================================
TOP 10 MEMORY USES FOR SGA HEAP SUB POOL 1
----------------------------------------------
"KJSC rnb slots                 "    30 GB 60%
TOP 10 MEMORY USES FOR SGA HEAP SUB POOL 2
----------------------------------------------
"KJSC rnb slots                 "    34 GB 60%
TOP 10 MEMORY USES FOR SGA HEAP SUB POOL 3
----------------------------------------------
"KJSC rnb slots                 "    40 GB 68%
TOP 10 MEMORY USES FOR SGA HEAP SUB POOL 4
----------------------------------------------
"KJSC rnb slots                 "    33 GB 61%
==============================================
TOP 10 MEMORY USES FOR SGA HEAP SUB POOL 5
----------------------------------------------
"KJSC rnb slots                 "    39 GB 65%
==============================================
TOP 10 MEMORY USES FOR SGA HEAP SUB POOL 6
----------------------------------------------
"KJSC rnb slots                 "    38 GB 63%
==============================================
TOP 10 MEMORY USES FOR SGA HEAP SUB POOL 7
----------------------------------------------
"KJSC rnb slots                 "    36 GB 65%
...
==============================================
TOP 20 MEMORY USES ACROSS SGA HEAP 1 - 7
----------------------------------------------
"KJSC rnb slots                 "   250 GB 63%

TOTALS
---------------------------------------
Total free memory                   119 GB
Total memory alloc.                 275 GB
Grand total                         394 GB

 

Changes

Upgrade to 19c
+
High number of sessions connected to the database.

Cause

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In this Document
Symptoms
Changes
Cause
Solution
References


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