DeadLock
http://blog.sina.com.cn/s/blog_5384afff0100rtcg.html
DeadLock
Step 1
create table t1 and t2
create table t1 (a int);
create table t2 (a int);
Step 2
insert values
insert into t1 values (1);
insert into t2 values (2);
Step 3
update t1 and t2 value as 1000 and 2000 and not commit in first session and second session
session1
update t1 set a = 1000 where a = 1; (not commit)
session2
update t2 set a = 2000 where a = 2; (not commit)
Step 4
to session 1 update table t2 same value,then find lock_wait(because session 2 has been execute the action,the line
has been locked !!)
session1
update t2 set a = 2000 where a = 2;
Solution:
First Check
sys@ORCL>@lock.sql
lock lock
holder holder lock lock request blocked
username session id SERIAL# type id1 id2 mode mode BLOCK session id
------------------ ----------- ---------- ------ ----------- ----------- --------- --------- ---------- ----------
USER1 6 7 AE 100 0 4 0 0
USER1 123 51 AE 100 0 4 0 0
USER1 123 51 TM 86646 0 3 0 0
USER1 123 51 TM 86645 0 3 0 0
USER1 123 51 TX 589831 1179 6 0 0
USER1 364 53 AE 100 0 4 0 0
USER1 365 47 AE 100 0 4 0 0
USER1 365 47 TM 86646 0 3 0 0
USER1 365 47 TX 65547 1183 6 0 1 123
SYS 124 319 AE 100 0 4 0 0
3 1 CF 0 0 2 0 0
3 1 RD 1 0 1 0 0
3 1 RS 25 1 2 0 0
3 1 XR 4 0 1 0 0
121 1 TS 3 1 3 0 0
121 1 TS 8 1 3 0 0
239 1 PW 1 0 3 0 0
357 1 KD 0 0 6 0 0
357 1 KT 12876 0 4 0 0
358 1 RT 1 0 6 0 0
359 1 AE 100 0 4 0 0
已选择21行。
sys@ORCL>
througth the output,we can find the lock wait session is 123.
then we check v$session
sys@ORCL>select sid,serial#,TERMINAL,PROGRAM from v$session where TERMINAL <> 'UNKNOWN';
SID SERIAL# TERMINAL PROGRAM
---------- ---------- ------------------------------ ------------------------------------------------
6 7 0101—PC plsqldev.exe
123 51 pts/2 [email protected] (TNS V1-V3)
124 319 pts/4 [email protected] (TNS V1-V3)
364 53 0101—PC plsqldev.exe
365 47 0101—PC plsqldev.exe
sys@ORCL>
finaly:
alter system kill session '123,51';
the lock wait session 2 has been killed:
USER1@ORCL>update t2 set a = 2000 where a = 2;
ERROR:
ORA-03114: 未连接到 ORACLE
update t2 set a = 2000 where a = 2
*
第 1 行出现错误:
ORA-00028: your session has been killed
ORA-00028: your session has been killed
USER1@ORCL>
@lock.sql
set pages 1000 lin 126
col kaddr heading 'lock|address'
col username heading 'lock|holder|username' for a18
col sid heading 'lock|holder|session id' format 9999999999
col type heading 'lock|type' format a6
col id1 heading 'id1' format 9999999999
col id2 heading 'id2' format 9999999999
col lmode heading 'lock|mode' format 99999999
col request heading 'request|mode' format 99999999
col blocking_sid format 999999 heading 'blocked|session id'
select /*+rule*/
-- a.kaddr, --
(select username from v$session where sid = a.sid) username,
a.sid,
(select serial# from v$session where sid = a.sid) serial#,
-- (select ctime from v$lock where KADDR = a.kaddr) ctime, --
a.type,
a.id1,
a.id2,
a.lmode,
a.request,
a.block,
b.sid blocking_sid
from v$lock a,
( select * from v$lock
where request > 0
and type <> 'MR'
) b
where a.id1 = b.id1(+)
and a.id2 = b.id2(+)
and a.lmode > 0
and a.type <> 'MR'
order by username,a.sid,serial#,a.type
/
column sid clear
column type clear
column request clear
column username clear