ORA-12519, TNS:no appropriate service handler found The Connection descriptor used by the client was

遇到连接Oracle的问题，报错如题：ORA-12519: TNS:no appropriate service handler found，应该是项目中的有些算法把所有连接都占用了，没办法只能增大数据的连接，具体做法如下：

select count(*) from v$process; --当前的连接数
select value from v$parameter where name = 'processes'; --数据库允许的最大连接数

修改最大连接数:
alter system set processes = 3000 scope = spfile;

shell重启数据库:
shutdown immediate;
startup;

--查看当前有哪些用户正在使用数据
SELECT osuser, a.username,cpu_time/executions/1000000||'s', sql_fulltext,machine 
from v$session a, v$sqlarea b
where a.sql_address =b.address order by cpu_time/executions desc;

转载：ORA-12519: TNS:no appropriate service handler found 解决_zz87250976的专栏