How to modify the settings for the number of Oracle concurrent connections

Unable to connect to Oracle database, prompt for related errors

oerr:ora-12519 tns:no appropriate service handler found

Intermittent failure of client connection, error ORA-12519

Cause:the Listener could no available service handlers that are

Appropriate for the client connection.

Action:run "LSNRCTL Services" to ensure the instance (s) have registered

With the listener, and are accepting connections. Check Lsnrctl service, instance has been registered,

When the status shows ready, you can connect.

When the listener believes the current number of connections has reached maximum load,

It may set the state's service handler for a instance to "blocked" and begin refusing

Incoming client connections with either of the following errors:ora-12519 or ora-12516

The use of service dynamic registration, by Pmon through the service_update to the current connection, but service_update have time interval,

Therefore, the number of connections displayed by listener may be different from the current actual number of connections.

Search for solutions:

Check to see if the number of processes in the database has reached the size of the parameter processes.

1.select Count (*) from v$process; Gets the current number of processes for the database.

2.select value from V$parameter where name = ' processes '; Gets the upper limit of the number of processes.

3. If the ceiling has been reached, modify the size of the processes in the Initsid.ora.

4. Restart the database to the Nomount state, execute the Create SPFile from Pfile; and startup Open.

The maximum number of concurrent queries to the database since it was started

To modify the maximum number of connections:

alter system SET processes = Scope = SPFile;

To restart the database:

Shutdown immediate;

Startup

--See which users are currently using the data

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;