ORA-04031 Due To Excessive Growth In KGLH0 Heaps
(Doc ID 1351675.1)
Last updated on JUNE 30, 2023
Applies to:
Oracle Database - Enterprise Edition - Version 11.2.0.1 to 11.2.0.2 [Release 11.2]Oracle Database - Enterprise Edition - Version 11.2.0.3 to 11.2.0.3 [Release 11.2]
Oracle Database Exadata Cloud Machine - Version N/A and later
Oracle Cloud Infrastructure - Database Service - Version N/A and later
Oracle Database Exadata Express Cloud Service - Version N/A and later
Information in this document applies to any platform.
Symptoms
In an 11.2 database, the "KGLH0" heap seems overallocated, leading in time to an ORA-4031 error.
KGLH0 associated with the SQL Area in the Shared Pool. Each child cursor consumes KGLH0.
Large allocation in KGLH0 can occur due to many child cursors and a lack of sharing of the parent cursor.
The trace file generated with the ORA-04031 error shows large allocations of the KGLH0 heap chunks:
Memory Utilization of Subpool 1
===============================
Allocation Name Size
___________________________ ____________
"free memory " 101779936
"SQLA " 390848
"KGLH0 " 653554600 <<<
===============================
Memory Utilization of Subpool 2
===============================
Allocation Name Size
___________________________ ____________
"free memory " 61765736
"SQLA " 310364504
"KGLH0 " 250430528 <<<
When witnessing a high allocation for the KGLH0 heap chunks in the trace file , a heap dump can be taken to get more detailed information:
In this case the main culprit is memory allocations of the "kkscsAddChildNo" type.
Changes
Cause
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In this Document
| Symptoms |
| Changes |
| Cause |
| Solution |
| References |