public class Program
    {
        public static void Main(string[] args)
        {
            for (var i = 0; i < 1000; i++)
            {
                Npgsql.NpgsqlConnection.ClearAllPools();

                var conStr = $"User ID=docker;Password={i};Host=postgres;Port=5432;Database=postgres;Connection Idle Lifetime=10;Connection Pruning Interval=5";
                using var connection = new NpgsqlConnection(conStr);

                connection.Open();

                using var cmd = new NpgsqlCommand("select 1", connection);
                cmd.Prepare();

                using var reader = cmd.ExecuteReader();
                while (reader.Read())
                {
                    // do nothing
                }
                connection.Close();
                Thread.Sleep(5);
            }
        }
    }