ORA-04031: Unable To Allocate 32 Bytes Of Shared Memory
記錄一次生產庫遇到的4031錯誤，後來通過調整sga大小將問題解決了
報錯信息：
ORA-04031: 無法分配 32 字節的共享內存 ("shared pool","select user#,password,datats...","SQLA","tmp")
Incident details in: /u01/app/oracle/diag/rdbms/twprod/xxxxx/incident/incdir_237848/xxxxx_ora_36005_i237848.trc
Use ADRCI or Support Workbench to package the incident.
See Note 411.1 at My Oracle Support for error and packaging details.
Tue Jun 06 19:57:24 2017
Errors in file /u01/app/oracle/diag/rdbms/xxxx/xxxx/trace/xxxx_e004_106234.trc (incident=238416):
ORA-04031: unable to allocate 32 bytes of shared memory ("shared pool","select /*+ INDEX(TAB AQ$_AQ...","SQLA","tmp")
Incident details in: /u01/app/oracle/diag/rdbms/xxxx/xxxx1/incident/incdir_238416/xxxx1_e004_106234_i238416.trc
查看當前sga設置：
SYS@ xxxx1> show parameter sga
NAME TYPE VALUE
------------------------------------ ----------- ------------------------------
lock_sga boolean FALSE
pre_page_sga boolean FALSE
sga_max_size big integer 20G
sga_target big integer 20G
調整sga為30g並重啟數據庫使參數生效：
SYS@ xxxx1> alter system set sga_max_size=30G scope=spfile;
SYS@ xxxx1> alter system set sga_target=30G scop=spfile;
SYS@ xxxx1> shutdown immediate
SYS@ xxxx1> startup
以下是Mos的解決方法，以供參考：
ORA-04031: Unable To Allocate 32 Bytes Of Shared Memory ("shared pool","select tablespace_id, rfno, ...","SQLA","tmp")" (
In this Document
APPLIES TO:
Oracle Database - Enterprise Edition - Version 11.2.0.2 and later
Information in this document applies to any platform.
SYMPTOMS
Alert log reports errors like below in almost all the instances:
ORA-04031: unable to allocate 32 bytes of shared memory ("shared pool","select tablespace_id, rfno, ...","SQLA","tmp")"
CAUSE
The trace file shows there are 6 sga subpools allocated.
...
****************** End of process map dump ************
==============================================
TOP 10 MEMORY USES FOR SGA HEAP SUB POOL 1
----------------------------------------------
"KGH: NO ACCESS " 4056 MB 61%
"gcs dynamic s " 713 MB 11%
"free memory " 625 MB 9%
"gcs dynamic r " 501 MB 8%
"init_heap_kfsg " 195 MB 3%
"FileOpenBlock " 122 MB 2%
"gcs resources " 64 MB 1%
"ges enqueues " 62 MB 1%
"gcs shadows " 45 MB 1%
"PRTMV " 40 MB 1%
-----------------------------------------
free memory 625 MB
memory alloc. 6031 MB
Sub total 6656 MB
==============================================
TOP 10 MEMORY USES FOR SGA HEAP SUB POOL 2
----------------------------------------------
"KGH: NO ACCESS " 3822 MB 71%
"free memory " 343 MB 6%
"SQLA " 223 MB 4%
"gcs dynamic r " 146 MB 3%
"KGLH0 " 126 MB 2%
"gcs dynamic s " 98 MB 2%
"gc name table " 96 MB 2%
"ges resource " 78 MB 1%
"PRTMV " 68 MB 1%
"gcs resources " 65 MB 1%
-----------------------------------------
free memory 343 MB
memory alloc. 5033 MB
Sub total 5376 MB
==============================================
TOP 10 MEMORY USES FOR SGA HEAP SUB POOL 3
----------------------------------------------
"KGH: NO ACCESS " 3812 MB 80%
"free memory " 215 MB 5%
"SQLA " 112 MB 2%
"KGLH0 " 97 MB 2%
"ges resource " 80 MB 2%
"gcs resources " 66 MB 1%
"gcs shadows " 46 MB 1%
"PRTMV " 45 MB 1%
"KQR X PO " 44 MB 1%
"ges enqueues " 22 MB 0%
-----------------------------------------
free memory 215 MB
memory alloc. 4521 MB
Sub total 4736 MB
==============================================
TOP 10 MEMORY USES FOR SGA HEAP SUB POOL 4
----------------------------------------------
"KGH: NO ACCESS " 3557 MB 79%
"free memory " 367 MB 8%
"KQR L PO " 79 MB 2%
"KGLH0 " 76 MB 2%
"gcs resources " 66 MB 1%
"SQLA " 61 MB 1%
"gcs shadows " 45 MB 1%
"PRTMV " 39 MB 1%
"ges enqueues " 16 MB 0%
"KGLHD " 12 MB 0%
-----------------------------------------
free memory 367 MB
memory alloc. 4113 MB
Sub total 4480 MB
==============================================
TOP 10 MEMORY USES FOR SGA HEAP SUB POOL 5
----------------------------------------------
"KGH: NO ACCESS " 3689 MB 85%
"free memory " 215 MB 5%
"KGLH0 " 74 MB 2%
"gcs resources " 65 MB 2%
"gcs shadows " 44 MB 1%
"PRTMV " 40 MB 1%
"SQLA " 32 MB 1%
"ges enqueues " 24 MB 1%
"db_block_hash_buckets " 21 MB 0%
"KGLHD " 12 MB 0%
-----------------------------------------
free memory 215 MB
memory alloc. 4137 MB
Sub total 4352 MB
==============================================
TOP 10 MEMORY USES FOR SGA HEAP SUB POOL 6
----------------------------------------------
"KGH: NO ACCESS " 3685 MB 76%
"free memory " 240 MB 5%
"gcs dynamic s " 138 MB 3%
"flashback generation buff " 122 MB 2%
"SQLA " 116 MB 2%
"gcs dynamic r " 106 MB 2%
"KGLH0 " 91 MB 2%
"gcs resources " 64 MB 1%
"gcs shadows " 44 MB 1%
"PRTMV " 41 MB 1%
-----------------------------------------
free memory 240 MB
memory alloc. 4624 MB
Sub total 4864 MB
TOTALS ---------------------------------------
Total free memory 2005 MB
Total memory alloc. 28 GB
Grand total 30 GB
==============================================
There are 6 subpools created in the SGA and a high amount of memory is allocated to "KGH: NO ACCESS "
There are multiple bugs open on the same but on 11gR2 there is no actual fix.
SOLUTION
As a solution for the issue you can disable the use of durations.
The shared pool can have subpools with 4 durations. These durations are "instance", "session", "cursor", and "execution". By default these durations are separate from each other.
The disable durations, you have to set the underscore parameter:
"_enable_shared_pool_durations = false"
This is recommended by development for all similar issues.
The main advantage of "_enable_shared_pool_durations = false" is that all the durations are combined into one pool and so a duration will not run out while another duration has free memory.
This issue will be fixed in 12c version due to architectural changes which will allow less need of durations for subpools.
Note:
Please note that unpublished Enhancement Request Bug 8857940 - NEED COMMON DURATIONS FOR UNSHRINKABLE POOLS 8857940, fixed starting with 12.1.0.1, addresses the durations issue as well. With the fix for Bug 8857940 in place, Oracle permits to group the shared pool durations in 2 groups to allow better shareability of the memory and avoid the ORA-4031 errors.
Another possible solution is to apply Patch 8857940 if it is available for your platform and version.
REFERENCES
BUG:19236833 - EXADATA: ORA-04031: UNABLE TO ALLOCATE 32 BYTES OF SHARED MEMORY "SQLA" "TMP"
NOTE:411.1 - ADR Different Methods to Create IPS Package
BUG:17789414 - SUPERCLUSTER: ORA-4031 ERRORS OCCURING WEEKLY CAUSING INSTANCE CRASHES
BUG:20447919 - ORA-4031: UNABLE TO ALLOCATE 32 BYTES
ORA-04031: Unable To Allocate 32 Bytes Of Shared Memory