Oracle 阻塞(blocking blocked)介绍和实例演示

--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;