今天碰到一个问题，有一张表不能操作，很可能是被锁了，首先想到的是kill session，于是执行了下列的脚本找到是哪个session有问题：
select object_name, machine, s.sid,s.serial#
from v$locked_object l, dba_objects o, v$session s
where l.object_id = o.object_id
and l.session_id =s.sid;
发现有一个会话有锁sid 197,serial# 17，于是执行alter system kill session ‘197,17’;大概等了30s中，pl/sql developer报出一个错误:ora-00031:标记要终止的会话。
解决方法：查出session的spid
select spid, osuser, s.program
from v$session s, v$process p
where s.paddr = p.addr
and s.sid =197;
1. 在linux上， kill -9 12345
2. 在windows上，C:Documents and Settingsgg>orakill orcl 12345
orcl：表示要杀死的进程属于的实例名
12345：是要杀掉的线程号
ORA-00031: session marked for kill
Cause: The session specified in an ALTER SYSTEM KILL SESSION command cannot bekilled immediately (because it is rolling back or blocked on a networkoperation), but it has been marked for kill. This means it will be killed as soonas possible after its current uninterruptible operation is done.
Action: No action is required for the session to be killed, but further executionsof the ALTER SYSTEM KILL SESSION command on this session may cause the sessionto be killed sooner.