Java + Oracle ORA-1000超过最大打开游标

Question

I have a multithreaded application where the main thread creates a few threads and hands them off to the ExecutorService. All the threads use a Oracle Database connection object in the main class. The database connection is opened once and all the methods in the other threads use the main database object.

However once the application starts running and processing the records, I see that the number of cursors open keeps increasing until 2000 ( I set this limit in Oracle ) and then results in the ORA-1000 message which do not go away until I restart the application. I am closing the resultsets on all the methods as well as the statements and am unable to figure out why the cursor count doesnt decrease ( Even when I run a single thread )

Here is one method:

private boolean GetPending()
{
    try {
        String statement = "SELECT * FROM PENDING_REQUESTS WHERE REQUEST_ID = GET_PENDING()";
        PreparedStatement query = DbConnection.prepareStatement(statement);
        ResultSet rs = query.executeQuery();
        while (rs.next()) {
            MSISDN = rs.getInt(3);
            SHORTCODE = rs.getInt(4);
            MESSAGE = rs.getString(5);
            return true;
        }
        rs.close();
        query.close();
    }
    catch(SQLException e) {
        LogWriter.Log("ID:"+ID+"\t\tError returning field: " + e.toString());
    }
    return false;   
}

I have also noticed that if I release the connection when the error occurs, the cursors are released. However I do not want to create a new connection for each new request since it will slow down the entire application.

Any help is appreciated. Thanks

Answer 1

Few problems there:

You are not closing your connections. Close your connections on the finally .

You are not closing rs or query (+1 immibis)

Have you thought of using a Spring jdbc template? Also check on connection pools. They are your friend.

Answer 2

You need to close resultSet and prepared statement. In your code it is not done. The best way is to do this in final block so even if exception happens resultSet are properly closed or if you use java7 use try-with-resources