Oracle阻塞(blockingblocked)实例详解

--更新表，注，提示符scott@CNMMBO表明用户为scott的session，用户名不同，session不同。

scott@CNMMBO> update emp set sal=sal*1.1 where empno=7788;

1 row updated.

scott@CNMMBO> @my_env

SPID        SID  SERIAL# USERNAME    PROGRAM

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

11205       1073    4642 robin      oracle@SZDB (TNS V1-V3)

--另起两个session更新同样的行，这两个session都会处于等待，直到第一个session提交或回滚

leshami@CNMMBO> update scott.emp set sal=sal+100 where empno=7788;

goex_admin@CNMMBO> update scott.emp set sal=sal-50 where empno=7788;

--下面在第一个session 查询阻塞情况

scott@CNMMBO> @blocker

BLOCK_MSG                        BLOCK

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

pts/5 ( '1073,4642' ) is blocking 1067,10438         1

pts/5 ( '1073,4642' ) is blocking 1065,4464          1

--上面的结果表明session 1073,4642 阻塞了后面的2个

--即session 1073,4642是阻塞者，后面2个session是被阻塞者

--Author : Leshami

--Blog  : http://blog.csdn.net/leshami

--下面查询正在阻塞的session id，SQL语句以及被阻塞的时间

scott@CNMMBO> @blocking_session_detail.sql

'SID=' ||A.SID|| 'WAITCLASS=' ||A.WAIT_CLASS|| 'TIME=' ||A.SECONDS_IN_WAIT||CHR(10)|| 'QUERY=' ||B.SQL_TEXT

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

sid=1067 Wait Class=Application Time =5995

  Query= update scott.emp set sal=sal+100 where empno=7788

sid=1065 Wait Class=Application Time =225

  Query= update scott.emp set sal=sal-50 where empno=7788

--下面的查询阻塞时锁的持有情况

scott@CNMMBO> @request_lock_type

USERNAME               SID TY LMODE    REQUEST      ID1    ID2

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

SCOTT                1073 TX Exclusive  None      524319   27412

LESHAMI               1067 TX None    Exclusive    524319   27412

GOEX_ADMIN              1065 TX None    Exclusive    524319   27412

--可以看到LESHAMI，GOEX_ADMIN 2个用户都在请求524319/27412上的Exclusive锁，而此时已经被SCOTT加了Exclusive锁

--查询阻塞时锁的持有详细信息

scott@CNMMBO> @request_lock_detail

     SID USERNAME       OSUSER     TERMINAL         OBJECT_NAME     TY Lock Mode  Req_Mode

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

    1065 GOEX_ADMIN      robin      pts/1           EMP         TM Row Excl

    1065 GOEX_ADMIN      robin      pts/1           Trans-524319     TX --Waiting-- Exclusive

    1067 LESHAMI       robin      pts/0           EMP         TM Row Excl

    1067 LESHAMI       robin      pts/0           Trans-524319     TX --Waiting-- Exclusive

    1073 SCOTT        robin      pts/5           EMP         TM Row Excl

    1073 SCOTT        robin      pts/5           Trans-524319     TX Exclusive

robin@SZDB:~/dba_scripts/custom/sql> more my_env.sql

SELECT spid, s.sid, s.serial#, p.username, p.program

FROM v$process p, v$session s

WHERE p.addr = s.paddr

    AND s.sid = ( SELECT sid

           FROM v$mystat

           WHERE rownum = 1);

robin@SZDB:~/dba_scripts/custom/sql> more blocker.sql

col block_msg format a50;

select c.terminal|| ' (' '' ||a.sid|| ',' ||c.serial#|| '' ') is blocking ' ||b.sid|| ',' ||d.serial# block_msg, a.block

from v$lock a,v$lock b,v$session c,v$session d

  where a.id1=b.id1

  and a.id2=b.id2

  and a.block>0

  and a.sid <>b.sid

  and a.sid=c.sid

  and b.sid=d.SID;

robin@SZDB:~/dba_scripts/custom/sql> more blocking_session_detail.sql

--To find the query for blocking session

--Access Privileges: SELECT on v$session, v$sqlarea

SELECT    'sid='

      || a.SID

      || ' Wait Class='

      || a.wait_class

      || ' Time='

      || a.seconds_in_wait

      || CHR (10)

      || ' Query='

      || b.sql_text

   FROM v$session a, v$sqlarea b

   WHERE a.blocking_session IS NOT NULL AND a.sql_address = b.address

ORDER BY a.blocking_session

/

robin@SZDB:~/dba_scripts/custom/sql> more request_lock_type.sql

--This script generates a report of users waiting for locks.

--Access Privileges: SELECT on v$session, v$lock

SELECT sn.username, m.sid, m.type,

     DECODE(m.lmode, 0, 'None' ,

             1, 'Null' ,

             2, 'Row Share' ,

             3, 'Row Excl.' ,

             4, 'Share' ,

             5, 'S/Row Excl.' ,

             6, 'Exclusive' ,

         lmode, ltrim(to_char(lmode, '990' ))) lmode,

     DECODE(m.request,0, 'None' ,

              1, 'Null' ,

              2, 'Row Share' ,

              3, 'Row Excl.' ,

              4, 'Share' ,

              5, 'S/Row Excl.' ,

              6, 'Exclusive' ,

              request, ltrim(to_char(m.request,

         '990' ))) request, m.id1, m.id2

FROM v$session sn, v$lock m

WHERE (sn.sid = m.sid AND m.request != 0)

     OR (sn.sid = m.sid

         AND m.request = 0 AND lmode != 4

         AND (id1, id2) IN ( SELECT s.id1, s.id2

    FROM v$lock s

             WHERE request != 0

        AND s.id1 = m.id1

                 AND s.id2 = m.id2)

         )

ORDER BY id1, id2, m.request;

robin@SZDB:~/dba_scripts/custom/sql> more request_lock_detail.sql

set linesize 190

col osuser format a15

col username format a20 wrap

col object_name format a20 wrap

col terminal format a25 wrap

col Req_Mode format a20

select B.SID, C.USERNAME, C.OSUSER, C.TERMINAL,

     DECODE(B.ID2, 0, A.OBJECT_NAME,

       'Trans-' ||to_char(B.ID1)) OBJECT_NAME,

    B.TYPE,

     DECODE(B.LMODE,0, '--Waiting--' ,

            1, 'Null' ,

            2, 'Row Share' ,

            3, 'Row Excl' ,

           4, 'Share' ,

            5, 'Sha Row Exc' ,

       6, 'Exclusive' ,

             'Other' ) "Lock Mode" ,

     DECODE(B.REQUEST,0, ' ' ,

            1, 'Null' ,

            2, 'Row Share' ,

            3, 'Row Excl' ,

            4, 'Share' ,

            5, 'Sha Row Exc' ,

            6, 'Exclusive' ,

            'Other' ) "Req_Mode"

  from DBA_OBJECTS A, V$LOCK B, V$SESSION C

where A.OBJECT_ID(+) = B.ID1

  and B.SID = C.SID

  and C.USERNAME is not null

order by B.SID, B.ID2;