Increasing Shared Pool Buffers Due to "KJSC rnb slots" Allocation Leading to ORA-04031 Errors
(Doc ID 2772028.1)
Last updated on JULY 20, 2024
Applies to:
Oracle Database - Enterprise Edition - Version 19.1.0.0.0 and laterInformation 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:
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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%
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TOP 10 MEMORY USES FOR SGA HEAP SUB POOL 5
----------------------------------------------
"KJSC rnb slots " 39 GB 65%
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TOP 10 MEMORY USES FOR SGA HEAP SUB POOL 6
----------------------------------------------
"KJSC rnb slots " 38 GB 63%
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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
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Total free memory 119 GB
Total memory alloc. 275 GB
Grand total 394 GB
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 |