Oracle单实例情况下的library cache pin的问题模拟与问题分析
本机环境：Oracle 10.2.0.5 x86-64bit for RHEL5.8 x86-64bit
第一个session：
[oracle@localhost ~]$ sqlplus / as sysdba
SQL*Plus: Release 10.2.0.5.0 - Production on Fri Jun 12 17:27:28 2015
Copyright (c) 1982, 2010, Oracle. All Rights Reserved.
Connected to an idle instance.
SQL> startup
ORACLE instance started.
Total System Global Area 281018368 bytes
Fixed Size 2095672 bytes
Variable Size 96470472 bytes
Database Buffers 176160768 bytes
Redo Buffers 6291456 bytes
Database mounted.
Database opened.
SQL> create user lc0019999 identified by aaaaaa;
User created.
SQL> grant dba to lc0019999;
Grant succeeded.
SQL> create user lc0029999 identified by aaaaaa;
User created.
SQL> grant dba to lc0029999;
Grant succeeded.
SQL> create user lc0039999 identified by aaaaaa;
User created.
SQL> grant dba to lc0039999;
Grant succeeded.
SQL> conn lc0019999/aaaaaa
Connected.
SQL> show user
USER is "LC0019999"
SQL> select * from v$mystat where rownum<2;
SID STATISTIC# VALUE
---------- ---------- ----------
159 0 1
SQL> Create or replace procedure dummy is
2 begin
3 null;
4 end;
5 /
Procedure created.
SQL> Begin
2 Dummy;
3 Dbms_lock.sleep(1000);
4 End;
5 /
------------>一直sleep着
以lc0029999登陆新开的一个session
[oracle@localhost ~]$ sqlplus lc0029999/aaaaaa
SQL*Plus: Release 10.2.0.5.0 - Production on Fri Jun 12 17:34:04 2015
Copyright (c) 1982, 2010, Oracle. All Rights Reserved.
Connected to:
Oracle Database 10g Enterprise Edition Release 10.2.0.5.0 - 64bit Production
With the Partitioning, OLAP, Data Mining and Real Application Testing options
SQL> select * from v$mystat where rownum<2;
SID STATISTIC# VALUE
---------- ---------- ----------
158 0 1
SQL>
SQL> alter procedure lc0019999.dummy compile;
------------>一直hang着
以sys用户新开一个session
[oracle@localhost ~]$ sqlplus / as sysdba
SQL*Plus: Release 10.2.0.5.0 - Production on Fri Jun 12 17:31:33 2015
Copyright (c) 1982, 2010, Oracle. All Rights Reserved.
Connected to:
Oracle Database 10g Enterprise Edition Release 10.2.0.5.0 - 64bit Production
With the Partitioning, OLAP, Data Mining and Real Application Testing options
SQL> set line 200
SQL> select sid, serial#,event from v$session where event like '%library cache pin%';
SID SERIAL# EVENT
---------- ---------- ----------------------------------------------------------------
158 28 library cache pin
SQL> select sid, serial#,p1raw,event from v$session where event like '%library cache pin%';
SID SERIAL# P1RAW EVENT
---------- ---------- ---------------- --------------------------------------------------
158 28 000000006BFF19B0 library cache pin
SQL> col owner for a30
SQL> col object for a30
SQL> SELECT kglnaown "Owner", kglnaobj "Object"
2 FROM x$kglob
3 WHERE kglhdadr='000000006BFF19B0'---->上面查出的P1RAW值。
4 ; ---->该语句是查询出这个等待事件发生在哪个object上。
Owner Object
------------------------------ ------------------------------
LC0019999 DUMMY
SQL>
SQL> SELECT s.sid, kglpnmod "Mode", kglpnreq "Req"
2 FROM x$kglpn p, v$session s
3 WHERE p.kglpnuse=s.saddr
4 AND kglpnhdl='000000006BFF19B0';---->该语句是查询出这个等待事件的等待者sid（REQ>0）和持有者sid（Mode>0）
SID Mode Req
---------- ---------- ----------
158 0 3
159 2 0
SQL>
---补充：如下文字来源于：
<blockquote><strong><code>Mode</code></strong><span> </span>is the mode in which the pin is wanted. This is a number thus:<ul><li>2 - Share mode</li><li>3 - Exclusive mode</li></ul></blockquote>
An X request (3) will be blocked by any pins held S mode (2) on the object.
An S request (2) will be blocked by any X mode (3) pin held, or may queue behind some other X request.
