在for update 查询时，线程被阻塞
查询阻塞线程：
select object_name as 对象名称,s.sid,s.serial#,p.spid as 系统进程号
from v$locked_object l , dba_objects o , v$session s , v$process p
where l.object_id=o.object_id and l.session_id=s.sid and s.paddr=p.addr;
杀死线程
alter system kill session '600,32786';