ORA-4031錯誤

時間 2020-10-06

標籤 java sql ide spa component orm 對象內存欄目 Java 简体版

原文原文鏈接

1. ORA-4031錯誤的緣由，通常是大量的hard parse致使了shared pool中的free list中產生大量的內存小碎片，當一個須要很大內存來進行hard parse的sql語句到來時，沒法從free list中找到內存，即便進行內存的釋放，仍是不能找到符合的內存塊。從而報ORA-4031錯誤。java

2. ORA-4031錯誤的解決方法：

1）alter system flush shared_pool;將shared pool中的全部內存清空。該方法治標不治本。

2）共享SQL語句：規範SQL語句的書寫；使用綁定變量；找到沒有使用綁定變量的SQL：

select sql_fulltext from v$sql where executions=1 order by sql_text;

若是在結果中發現一系列僅僅字面值不一樣的SQL，則能夠修改cursor_sharing參數：

alter system set cursor_sharing = 'force'; 來強制使用綁定變量。

3）使用shared pool中的保留區：

select request_misses from v$shared_pool_reserved;

若是結果大於0，則能夠調大shared_pool_reserved的大小；

SQL> show parameter shared_pool

NAME TYPE VALUE

------------------------------------ ----------- ------------------------------

shared_pool_reserved_size big integer 4M

shared_pool_size big integer 0

alter system set shared_pool_reserved=xxM scope=both;

4）使用dbms_shared_pool.keep('對象名')將使用內存很大的對象keep在內存中：

先要執行：@?/rdbms/admin/dbmspool.sql

SQL> @?/rdbms/admin/dbmspool.sql

Package created.

Grant succeeded.

View created.

Package body created.

再查出須要keep的對象：

SQL> select owner,name,namespace,type,sharable_mem from v$db_object_cache where sharable_mem>10000

2 and (type='PACKAGE' or type='PACKAGE BODY' or type='FUNCTION' or type='PROCEDURE') and kept='NO';

OWNER NAME NAMESPACE TYPE SHARABLE_MEM

---------- ------------------------- ------------------ --------------- ------------

SYS DBMS_BACKUP_RESTORE TABLE/PROCEDURE PACKAGE 33215

SYSMAN EMD_COLLECTION BODY PACKAGE BODY 33233

SYS DBMS_SHARED_POOL BODY PACKAGE BODY 12644

SYS SYS$RAWTOANY TABLE/PROCEDURE FUNCTION 12640

SYSMAN EMD_MAINTENANCE TABLE/PROCEDURE PACKAGE 29030

SYSMAN EMD_MAINTENANCE BODY PACKAGE BODY 62930

SYSMAN MGMT_JOB_ENGINE BODY PACKAGE BODY 218914

SYSMAN EM_PING BODY PACKAGE BODY 29086

SYS DBMS_BACKUP_RESTORE BODY PACKAGE BODY 95519

SYSMAN EMD_LOADER TABLE/PROCEDURE PACKAGE 12641

SYSMAN EMD_LOADER BODY PACKAGE BODY 71861

SYS PRVT_HDM BODY PACKAGE BODY 43624

SYSMAN MGMT_JOB_ENGINE TABLE/PROCEDURE PACKAGE 24938

SYS STANDARD BODY PACKAGE BODY 24960

SYSMAN EM_SEVERITY_REPOS BODY PACKAGE BODY 33236

SYS PRVT_ADVISOR TABLE/PROCEDURE PACKAGE 12640

SYSMAN MGMT_GLOBAL TABLE/PROCEDURE PACKAGE 29902

SYS DBMS_STANDARD TABLE/PROCEDURE PACKAGE 24929

SYS DBMS_ADVISOR BODY PACKAGE BODY 25000

SYS PRVT_HDM TABLE/PROCEDURE PACKAGE 16732

SYS PRVT_ADVISOR BODY PACKAGE BODY 66780

SYS DBMS_RCVMAN TABLE/PROCEDURE PACKAGE 43295

SYS STANDARD TABLE/PROCEDURE PACKAGE 438648

SYS DBMS_RCVMAN BODY PACKAGE BODY 375759

24 rows selected.

5）增長shared_pool_size的大小：

SQL> select component,current_size from v$sga_dynamic_components;

COMPONENT CURRENT_SIZE

---------------------------------------------------------------- ------------

shared pool 75497472

large pool 4194304

java pool 4194304

streams pool 0

DEFAULT buffer cache 130023424

KEEP buffer cache 0

RECYCLE buffer cache 0

DEFAULT 2K buffer cache 0

DEFAULT 4K buffer cache 0

DEFAULT 8K buffer cache 0

DEFAULT 16K buffer cache 0

DEFAULT 32K buffer cache 0

ASM Buffer Cache 0

13 rows selected.

sga_max_size：SGA容許的最大值，修改必須重啓；

sga_target：必須小於sga_max_size, 表示當前SGA的最大值；

alter system set shared_pool_size=xxM scope=both;

3. 使用V$SHARED_POOL_ADVICE來設置shared pool的大小

V$SHARED_POOL_ADVICE displays information about estimated parse time in the shared pool for different pool sizes. The sizes range from 10% of the current shared pool size or the amount of pinned library cache memory (whichever is higher) to 200% of the current shared pool size, in equal intervals. The value of the interval depends on the current size of the shared pool.sql

Column	Datatype	Description
SHARED_POOL_SIZE_FOR_ESTIMATE	NUMBER	Shared pool size for the estimate (in megabytes)
SHARED_POOL_SIZE_FACTOR	NUMBER	Size factor with respect to the current shared pool size
ESTD_LC_SIZE	NUMBER	Estimated memory in use by the library cache (in megabytes)
ESTD_LC_MEMORY_OBJECTS	NUMBER	Estimated number of library cache memory objects in the shared pool of the specified size
ESTD_LC_TIME_SAVED	NUMBER	Estimated elapsed parse time saved (in seconds), owing to library cache memory objects being found in a shared pool of the specified size. This is the time that would have been spent in reloading the required objects in the shared pool had they been aged out due to insufficient amount of available free memory.
ESTD_LC_TIME_SAVED_FACTOR	NUMBER	Estimated parse time saved factor with respect to the current shared pool size
ESTD_LC_LOAD_TIME	NUMBER	Estimated elapsed time (in seconds) for parsing in a shared pool of the specified size
ESTD_LC_LOAD_TIME_FACTOR	NUMBER	Estimated load time factor with respect to the current shared pool size
ESTD_LC_MEMORY_OBJECT_HITS	NUMBER	Estimated number of times a library cache memory object was found in a shared pool of the specified size

能夠使用下面的SQL語句來預估shared pool的大小：

select 'Shared Pool' component,shared_pool_size_for_estimate estd_sp_size,estd_lc_time_saved_factor parse_time_factor,case when current_parse_time_elapsed_s + adjustment_s<0

then 0 else current_parse_time_elapsed_s + adjustment_s end response_time

from (

select shared_pool_size_for_estimate,shared_pool_size_factor,estd_lc_time_saved_factor,a.estd_lc_time_saved,e.value/100

current_parse_time_elapsed_s,c.estd_lc_time_saved - a.estd_lc_time_saved adjustment_s from v$shared_pool_advice a,

(select * from v$sysstat where name='parse time elapsed') e,

(select estd_lc_time_saved from v$shared_pool_advice where shared_pool_size_factor=1) c

);

COMPONENT ESTD_SP_SIZE PARSE_TIME_FACTOR RESPONSE_TIME

-------------- ----------------- ------------------------- -------------

Shared Pool 64 .9989 294.37

Shared Pool 72 1 257.37

Shared Pool 80 1.0009 226.37