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Heap Size Exceeds Notification Threshold

January 20, 2012 Leave a comment
Memory Notification: Library Cache Object loaded into SGA
Heap size ** K exceeds notification threshold (8192K)

These are warning messages only which should not cause any problems. These warning messages appear due to new event messaging mechanism and memory manager in 10g Release 2.

In 10g, there is a new undocumented parameter that sets the KGL heap size warning threshold. This parameter was not present in 10gR1. Warnings are written if heap size exceeds this threshold.

Set _kgl_large_heap_warning_threshold to a reasonable high value or zero to prevent these warning messages. Value needs to be set in bytes.

To find out the hidden¬†‘_kgl_large_heap_warning_threshold’¬†parameter value in the database:

SELECT a.ksppinm "Parameter",
b.ksppstvl "Session Value",
c.ksppstvl "Instance Value"
FROM x$ksppi a, x$ksppcv b, x$ksppsv c
WHERE a.indx = b.indx AND
a.indx = c.indx AND
a.ksppinm LIKE '%kgl_large_heap%';
Parameter Session Value Instance Value
--------------------------------- ------- -------
_kgl_large_heap_warning_threshold 2097152 2097152

If you want to set this to 8192 (8192 * 1024) and are using an spfile:

(logged in as “/ as sysdba”)

SQL> alter system set "_kgl_large_heap_warning_threshold"=8388608 scope=spfile ;
SQL> shutdown immediate
SQL> startup
If using an "old-style" init parameter,edit the init parameter file and add
_kgl_large_heap_warning_threshold=8388608

The default threshold in 10.2.0.1 is 2M. So these messages could show up frequently in some application environments. In 10.2.0.2, the threshold was increased to 50MB after regression tests, so this should be a reasonable and recommended value.

Check your product version:

select   BANNER
from     sys.v_$version;

Source / Reference: