发生PingException mscorlib.dll

Question

I'm trying to read ip address from .csv file and ping those addresses using PingAsync class. But I'm getting above exception in the following line.

await Task.WhenAll(pingTasks);

my full code is Given below please take a look.

Ping Method

private static async Task AsyncPingTask(List<string> ipaddress)
{
    try
    {
        Console.WriteLine("Ping Started");
        StringBuilder pingStringBuilder = new StringBuilder();


            var pingTasks = ipaddress.Select(ip =>
            {
                using (var ping = new Ping())
                {
                    return ping.SendPingAsync(ip);
                }
            }).ToList();

            Console.WriteLine("Ping Completed");

            await Task.WhenAll(pingTasks);


            foreach (var pingReply in pingTasks)
            {
                pingStringBuilder.Append(pingReply.Result.Address);
                pingStringBuilder.Append("-->");
                pingStringBuilder.Append(pingReply.Result.Status);
                pingStringBuilder.Append("-->");
                pingStringBuilder.Append(pingReply.Result.RoundtripTime.ToString());
                pingStringBuilder.AppendLine();
            }
            Console.WriteLine(pingStringBuilder.ToString());
            pingStringBuilder.Clear();                

    }
    catch (Exception ex)
    {
        Console.WriteLine(ex.Message.ToString());
        throw;
    }

    }

Main Method:

public static void Main()
{
    List<string> address = new List<string>();
    Task t = Task.Run(() =>
    {
        var reader = new StreamReader(File.OpenRead(Environment.CurrentDirectory+@"\address.csv"));
        while (!reader.EndOfStream)
        {
            var lines = reader.ReadLine();
            var values = lines.Split(';');
            address.Add(values[0]);
        }                
    });


    Console.WriteLine("List COunt is {0}",address.Count);
    Stopwatch timeSpan=Stopwatch.StartNew();


    t.Wait();            


    AsyncPingTask(address).Wait();

    Console.WriteLine(timeSpan.ElapsedMilliseconds);                        
    Console.ReadLine();
}

If I done any mistake please guide me.

Answer 1

This piece of code is the problem:

var pingTasks = ipaddress.Select(ip =>
{
    using (var ping = new Ping())
    {
        return ping.SendPingAsync(ip);
    }
}).ToList();

You're disposing the Ping class before the async operation has a chance to complete, since you're not awaiting on SendPingAsync , but simply returning the hot task it produces. This leads the the disposal prior to the completion of the operation.

Change your code to:

var pingTasks = ipaddress.Select(ip =>
{
    var ping = new Ping();
    return ping.SendPingAsync(ip);
}).ToList();