Google Cloud Sql connection get dissconnected after some time

import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.sql.Statement;
import java.util.Calendar;

import com.client.DBConnection;
import com.google.appengine.api.rdbms.AppEngineDriver;
import com.google.gwt.user.client.Window;
import com.google.gwt.user.server.rpc.RemoteServiceServlet;

@SuppressWarnings("serial")
public class DBConnectionImpl extends RemoteServiceServlet implements DBConnection {
private static final long serialVersionUID = 1L;
private Connection conn = null;
private String status;

private String[][] Data1;
private String[][] Data;
private String[][] Data2;
private String[][] Data3;

public DBConnectionImpl() {
try {
DriverManager.registerDriver(new AppEngineDriver());

//Class.forName(driver).newInstance();
conn = DriverManager.getConnection("jdbc:google:rdbms://deeprajgroup.com:ttsdeepraj:ttsdb/tender_tracking"); //Gotchas in using JDBC with Cloud SQL
//conn = DriverManager.getConnection("jdbc:google:rdbms://cloudsql_project:testinstance/tender_tracking"); //Gotchas in using JDBC with Cloud SQL
} catch (Exception e) {
//NEVER catch exceptions like this
}
}
}Hi,

I have created one project using GWT and Google Cloud Sql(database) and this i deployed on the Google App Engine. When i deployed the project then at that time when i see my on net ie. http://tendertrackingsystemapp.appspot.com this will show the data from Google Cloud Sql but after 30 min - 1 hr this will give exception "Node Clicked: 500 The call failed on the server; see server log for details"

and data didn't displayed.

Please help me out from this problem ASAP.

Thx.

Regards

Neha