Oracle RAC環境下的阻塞(blocking blocked)介紹和執行個體示範_oracle

RAC環境下的阻塞不同於單一實例情形，因為我們需要考慮到位於不同執行個體的session。也就是說之前查詢的v$session，v$lock相應的應變化為全域範圍來尋找。本文提供了2個查詢指令碼，並給出執行個體示範那些session為阻塞者，哪些為被阻塞者。有關阻塞的概念以及單一實例環境下的阻塞請參考：Oracle 阻塞(blocking blocked)

1、示範環境

scott@DEVDB> select * from v$version where rownum<2;BANNER--------------------------------------------------------------------------------Oracle Database 11g Enterprise Edition Release 11.2.0.3.0 - 64bit Production--在scott session中發布SQL語句，並未提交scott@DEVDB> begin 2 update emp set sal=sal+100 where empno=7788; 3 update dept set dname='DBA' where deptno=10; 4 end; 5 /PL/SQL procedure successfully completed.--在leshami session中更新emp對象leshami@DEVDB> update scott.emp set sal=sal-200 where empno=7788;--在usr1 session中更新emp對象usr1@DEVDB> update scott.dept set dname='DEV' where deptno=10;

2、尋找阻塞

scott@DEVDB> @block_session_racUSER_STATUS   SID_SERIAL   CONN_INSTANCE   SID PROGRAM            OSUSER MACHINE     LOCK_TYPE    LOCK_MODE    CTIME OBJECT_NAME--------------- --------------- ---------------- ---- ------------------------------ ------- --------------- --------------- ----------- ---------- -------------------------Blocking ->   '20,1545'    devdb1       20 sqlplus@Linux-01 (TNS V1-V3)  oracle Linux-01    Transaction   Exclusive     666 DEPTBlocking ->   '20,1545'    devdb1       20 sqlplus@Linux-01 (TNS V1-V3)  oracle Linux-01    Transaction   Exclusive     666 EMPWaiting     '49,1007'    devdb1       49 sqlplus@Linux-01 (TNS V1-V3)  oracle Linux-01    Transaction   None        618 EMPWaiting     '933,11691'   devdb2      933 sqlplus@Linux-02 (TNS V1-V3)  oracle Linux-02    Transaction   None        558 DEPT--通過上述指令碼我們可以看到session '20,1545' 鎖住了對象DEPT以及EMP，而此時session '49,1007'與'933,11691'處於等待狀態。--下面是另外的一種方式來擷取阻塞的情形scott@DEVDB> @block_session_rac2BLOCKING_STATUS----------------------------------------------------------------------------------------------------------------------------SCOTT@Linux-01 ( INST=1 SID=20 Serail#=1545 ) IS BLOCKING USR1@Linux-02 ( INST=2 SID=933 Serial#=11691 )SCOTT@Linux-01 ( INST=1 SID=20 Serail#=1545 ) IS BLOCKING LESHAMI@Linux-01 ( INST=1 SID=49 Serial#=1007 )--Author : Leshami--Blog  : http://blog.csdn.net/leshami

3、示範中用到的指令碼

[oracle@Linux-01 ~]$ more block_session_rac.sql set linesize 180col user_status format a15col sid_serial format a15col program format a30 wrappedcol machine format a15 wrappedcol osuser format a15 wrappedcol conn_instance format a15col object_name format a25 wrapped SELECT DECODE (l.block, 0, 'Waiting', 'Blocking ->') user_status,     CHR (39) || s.sid || ',' || s.serial# || CHR (39) sid_serial,     (SELECT instance_name      FROM gv$instance      WHERE inst_id = l.inst_id)      conn_instance,     s.sid,     s.program,     s.osuser,     s.machine,     DECODE (l.TYPE,         'RT', 'Redo Log Buffer',         'TD', 'Dictionary',         'TM', 'DML',         'TS', 'Temp Segments',         'TX', 'Transaction',         'UL', 'User',         'RW', 'Row Wait',         l.TYPE)      lock_type--,id1           --,id2     ,     DECODE (l.lmode,         0, 'None',         1, 'Null',         2, 'Row Share',         3, 'Row Excl.',         4, 'Share',         5, 'S/Row Excl.',         6, 'Exclusive',         LTRIM (TO_CHAR (lmode, '990')))      lock_mode,     ctime--,DECODE(l.BLOCK, 0, 'Not Blocking', 1, 'Blocking', 2, 'Global') lock_status     ,     object_name  FROM gv$lock l     JOIN gv$session s ON (l.inst_id = s.inst_id AND l.sid = s.sid)     JOIN gv$locked_object o      ON (o.inst_id = s.inst_id AND s.sid = o.session_id)     JOIN dba_objects d ON (d.object_id = o.object_id)  WHERE (l.id1, l.id2, l.TYPE) IN (SELECT id1, id2, TYPE                   FROM gv$lock                   WHERE request > 0)ORDER BY id1, id2, ctime DESC;[oracle@Linux-01 ~]$ more block_session_rac2.sql SELECT DISTINCT     s1.username    || '@'    || s1.machine    || ' ( INST='    || s1.inst_id    || ' SID='    || s1.sid    || ' Serail#='    || s1.serial#    || ' ) IS BLOCKING '    || s2.username    || '@'    || s2.machine    || ' ( INST='    || s2.inst_id    || ' SID='    || s2.sid    || ' Serial#='    || s2.serial#    || ' ) '     AS blocking_status FROM gv$lock l1,    gv$session s1,    gv$lock l2,    gv$session s2 WHERE   s1.sid = l1.sid    AND s2.sid = l2.sid    AND s1.inst_id = l1.inst_id    AND s2.inst_id = l2.inst_id    AND l1.block > 0    AND l2.request > 0    AND l1.id1 = l2.id1    AND l1.id2 = l2.id2;