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oracle library cache lock,【DB】彻底搞清楚library cache lock的成因和解决方法（一）

發布時間：2024/9/30 编程问答 49 豆豆

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問題描述：

接到應用人員的報告，說是在任何對表CSNOZ629926699966的操作都會hang，包括desc CSNOZ629926699966,例如：

> sqlplus

SQL*Plus: Release 9.2.0.4.0 - Production on Mon Jan 10 10:11:06 2005

Connected to:

Oracle9i Enterprise Edition Release 9.2.0.4.0 - 64bit Production

With the Partitioning and Real Application Clusters options

JServer Release 9.2.0.4.0 - Production

SQL> conn pubuser/pubuser

Connected.

SQL> desc CSNOZ629926699966

。。。

這個進程 hang 了

。。。

詢問了一下之前有無特別的操作，業務人員說很久以前執行了腳本，但是該教本運行很久都沒有結果，然后他就退出了會話，再之后，就出現了上面的情況。腳本內容如下：$ cat CSNOZ629926699966.sh

#!/bin/sh

sqlplus??<< EOF? #use your username/password

create table CSNOZ629926699966 as select * from CSNOZ62992266cs

where mid not in ( select mid from??where servid='020999011964' and status in ('A','B','S'));

exit;

解決過程：?> sqlplus "/ as sysdba"

SQL*Plus: Release 9.2.0.4.0 - Production on Mon Jan 10 10:19:13 2005

Connected to:

Oracle9i Enterprise Edition Release 9.2.0.4.0 - 64bit Production

With the Partitioning and Real Application Clusters options

JServer Release 9.2.0.4.0 - Production

SQL> select * from v$lock where block=1;

no rows selected

SQL> /

no rows selected

SQL> /

no rows selected

SQL>

我們看到目前沒有鎖的信息

SQL> select xidusn, object_id, session_id, locked_mode from v$locked_object;

。。。

XIDUSN? OBJECT_ID SESSION_ID LOCKED_MODE

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

14???????? 18???????? 37?????????? 3

。。。

SQL> /

。。。

XIDUSN? OBJECT_ID SESSION_ID LOCKED_MODE

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

14???????? 18???????? 37?????????? 3

。。。

SQL> /

。。。

XIDUSN? OBJECT_ID SESSION_ID LOCKED_MODE

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

14???????? 18???????? 37?????????? 3

。。。

SQL>

查找 v$locked_object，我們發現了一個可疑的會話，SID 37：

SQL> select object_name,owner,object_type from dba_objects where object_id=18;

。。。。。。

OBJECT_NAME??????????????????? OWNER????????????????????????? OBJECT_TYPE

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

OBJ$?????????????????????????? SYS??????????????????????????? TABLE

。。。。。。

SQL>

奇怪怎么一直有這個鎖？？

初步猜測是由于SID為37的會話執行了上面的DDL語句，并在語句未完成前異常退出，

造成了所有訪問那個(DDL語句中涉及到的)對象的進程都hang了。

接下來我們看看等待事件：

SQL> select event,sid,p1,p2,p3 from v$session_wait where event not like 'SQL*%' and event not like 'rdbms%';

EVENT??????????????????????????????????????????????????????????????????? P1???????? P2??????? SID

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

pmon timer????????????????????????????????????????????????????????????? 300????????? 0????????? 1

ges remote message?????????????????????????????????????????????????????? 32????????? 0????????? 4

gcs remote message?????????????????????????????????????????????????????? 64????????? 0????????? 5

gcs remote message?????????????????????????????????????????????????????? 64????????? 0????????? 7

smon timer????????????????????????????????????????????????????????????? 300????????? 0???????? 19

library cache lock?????????????????????????????????????????????? 1.3835E+19 1.3835E+19???????? 30wakeup time manager?????????????????????????????????????????????????????? 0????????? 0???????? 22

7 rows selected.