After the oracle Shared Server is created successfully, the number of jdbc connections is limited. The following error occurs: java. SQL. SQLException: I/O SOLUTION error Description: After configuring the Shared Server for oracle, there is no problem for a single user process to connect to the oracle instance through the Shared Server! However, if jdbc is used to create connections to 100 oracle instances in sequence (required by the Business System), java is reported. SQL. SQLException: Io exception: End of TNS data channel error. Test by writing a java program through jdbc connection, it is found that the circuits parameter determines the number of connections that can be connected to the oracle instance through the Shared Server. If the value of the circuits parameter is 10, a maximum of 10-3 = 7 connections (only test, may be inaccurate) are connected at the same time. And so on. Solution: Increase the number of connections by modifying the cicuits. Alter system set circuits = 100 scope = both;