Oracle阻塞(blockingblocked)实例详解 |
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本文标签：Oracle,阻塞 一、概述： 二、演示阻塞：
--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
三、文中涉及到的相关SQL脚本完整代码如下：
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;
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