RAC环境下的阻塞不同于单实例情形，因为我们需要考虑到位于不同实例的session。也就是说之前查询的v$session，v$lock相应的应变化为全局范围来查找。本文提供了2个查询脚本，并给出实例演示那些session为阻塞者，哪些为被阻塞者。有关阻塞的概念以及单实例环境下的阻塞请参考：Oracle 阻塞(blocking blocked)
1、演示环境
scott@DEVDB> select * from v$version where rownum<2; BANNER -------------------------------------------------------------------------------- Oracle Database 11g Enterprise Edition Release 11.2.0.3.0 - 64bit Production --在scott session中发布SQL语句，并未提交 scott@DEVDB> begin 2 update emp set sal=sal+100 where empno=7788; 3 update dept set dname='DBA' where deptno=10; 4 end; 5 / PL/SQL procedure successfully completed. --在leshami session中更新emp对象 leshami@DEVDB> update scott.emp set sal=sal-200 where empno=7788; --在usr1 session中更新emp对象 usr1@DEVDB> update scott.dept set dname='DEV' where deptno=10;
2、寻找阻塞
scott@DEVDB> @block_session_rac USER_STATUS SID_SERIAL CONN_INSTANCE SID PROGRAM OSUSER MACHINE LOCK_TYPE LOCK_MODE CTIME OBJECT_NAME --------------- --------------- ---------------- ---- ------------------------------ ------- --------------- --------------- ----------- ---------- ------------------------- Blocking -> '20,1545' devdb1 20 sqlplus@Linux-01 (TNS V1-V3) oracle Linux-01 Transaction Exclusive 666 DEPT Blocking -> '20,1545' devdb1 20 sqlplus@Linux-01 (TNS V1-V3) oracle Linux-01 Transaction Exclusive 666 EMP Waiting '49,1007' devdb1 49 sqlplus@Linux-01 (TNS V1-V3) oracle Linux-01 Transaction None 618 EMP Waiting '933,11691' devdb2 933 sqlplus@Linux-02 (TNS V1-V3) oracle Linux-02 Transaction None 558 DEPT --通过上述脚本我们可以看到session '20,1545' 锁住了对象DEPT以及EMP，而此时session '49,1007'与'933,11691'处于等待状态。 --下面是另外的一种方式来获取阻塞的情形 scott@DEVDB> @block_session_rac2 BLOCKING_STATUS ---------------------------------------------------------------------------------------------------------------------------- SCOTT@Linux-01 ( INST=1 SID=20 Serail#=1545 ) IS BLOCKING USR1@Linux-02 ( INST=2 SID=933 Serial#=11691 ) SCOTT@Linux-01 ( INST=1 SID=20 Serail#=1545 ) IS BLOCKING LESHAMI@Linux-01 ( INST=1 SID=49 Serial#=1007 ) --Author : Leshami --Blog :
3、演示中用到的脚本
[oracle@Linux-01 ~]$ more block_session_rac.sql set linesize 180 col user_status format a15 col sid_serial format a15 col program format a30 wrapped col machine format a15 wrapped col osuser format a15 wrapped col conn_instance format a15 col 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;
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