今天碰到下面Error:
Caused by: java.lang.Exception: Listener refused the connection with the following error:
ORA-12520, TNS:listener could not find available handler for requested type of server
此问题一般是processess不够引起的，增大即可。
select value from v$parameter where name = 'processes';
今天的情况是SCAN IP引起的。