How to make SqlConnection timeout more quickly

Question

I am using an SQL connection string with SqlClient.SqlConnection and specifying Connection Timeout=5 in the string, but it still waits 30 seconds before returning failure.

Answer 1

Update 2 I suggest rolling your own timeout. Something like this:

internal static class Program
{
    private static void Main(string[] args)
    {
        Console.WriteLine(SqlServerIsRunning("Server=foobar; Database=tempdb; Integrated Security=true", 5));
        Console.WriteLine(SqlServerIsRunning("Server=localhost; Database=tempdb; Integrated Security=true", 5));
    }

    private static bool SqlServerIsRunning(string baseConnectionString, int timeoutInSeconds)
    {
        bool result;

        using (SqlConnection sqlConnection = new SqlConnection(baseConnectionString + ";Connection Timeout=" + timeoutInSeconds))
        {
            Thread thread = new Thread(TryOpen);
            ManualResetEvent manualResetEvent = new ManualResetEvent(false);
            thread.Start(new Tuple(sqlConnection, manualResetEvent));
            result = manualResetEvent.WaitOne(timeoutInSeconds*1000);

            if (!result)
            {
                thread.Abort();
            }

            sqlConnection.Close();
        }

        return result;
    }

    private static void TryOpen(object input)
    {
        Tuple parameters = (Tuple)input;

        try
        {
            parameters.Item1.Open();
            parameters.Item1.Close();
            parameters.Item2.Set();
        }
        catch
        {
            // Eat any exception, we're not interested in it
        }
    }
}

Update 1

I've just tested this on my own computer using this code:

internal static class Program
{
    private static void Main(string[] args)
    {
        SqlConnection con = new SqlConnection("Server=localhost; Database=tempdb; Integrated Security=true;Connection Timeout=5");
        Console.WriteLine("Attempting to open connection with {0} second timeout, starting at {1}.", con.ConnectionTimeout, DateTime.Now.ToLongTimeString());

        try
        {
            con.Open();
            Console.WriteLine("Successfully opened connection at {0}.", DateTime.Now.ToLongTimeString());
        }
        catch (SqlException)
        {
            Console.WriteLine("SqlException raised at {0}.", DateTime.Now.ToLongTimeString());
        }
    }
}

and it obeys the Connection Timeout value in the connection string. This was with .NET 4 against SQL Server 2008 R2. Admittedly, it's a localhost connection which may give different results but it means I can't replicate the problem.

I can only suggest trying a similar chunk of code in your network environment and seeing if you continue to see long timeouts.

Old (incorrect) answer I incorrectly thought the ConnectionTimeout property was settable, but it isn't.

Try setting SqlConnection.ConnectionTimeout instead of using the connection string.