ShapSnmpLib(9.0.3) Result of observing memory test of GetResponseAsync method with dotMemory

The SocketAwaitable class seems to be leaking resources in #SNMP v 9.0.3. I think it is probably caused by strong reference.

• C# Events Memory Leak - Stack Overflow

So I prepared details that seems to be memory leak. I ran it in the situation where the following timeout occurs:

• The SNMP agent exists on host B, but it is not running.
• Running my test code (Console App) on host A.

My test code snippet is below:

private static async Task TestMemory()
{
    // Running this code on host A
    // The Snmp Agent on host B, but an agent is not listening...
    var message = new GetRequestMessage(0x4bed, VersionCode.V1, new OctetString("public"), new List<Variable> { new Variable(new ObjectIdentifier("1.3.6.1.2.1.1.1.0")) });
    for (int i = 0; i < 100; i++)
    {
        using (var cts = new CancellationTokenSource(TimeSpan.FromSeconds(0.5))) // timeout 500 msec.
        {
            try
            {
                var response = await message.GetResponseAsync(new IPEndPoint(IPAddress.Parse("IP OF HOST B"), 161))
                    .WithCancellation(cts.Token)
                    .ConfigureAwait(false);
            }
            catch (Exception ex)
            {
                Console.WriteLine("{0}", ex.Message);
            }
        }
    }

    message = null;
    GC.Collect();
    GC.WaitForPendingFinalizers();
    GC.Collect();
}
private static async Task<T> WithCancellation<T>(this Task<T> task, CancellationToken cancellationToken)
{
    var tcs = new TaskCompletionSource<bool>();
    using (cancellationToken.Register(state => ((TaskCompletionSource<bool>)state).TrySetResult(true), tcs))
    {
        var completedTask = await Task.WhenAny(task, tcs.Task).ConfigureAwait(false);
        if (task != completedTask)
        {
            throw new OperationCanceledException(cancellationToken);
        }
    }

    return await task.ConfigureAwait(false);
}

The snapshot with dotMemory is below:

1. Compare snapshots

2. Object Set(SocketAwaitable)

I think it is leaking with SocketAwaitable and SocketAsyncEventArgs.

It seems to leak in the following cases:

• When the SNMP Agent on the remote host does not respond (e.g. snmpd.exe is not listening):
  1. CancellationTokenSource raised an OperationCanceledException exception.
  2. The socket in the GetResponseAsync(this ISnmpMessage, IPEndPoint) method is not disposed.

Perhaps it may be necessary to overload the GetResponseAsync method to receive CancellationToken.

• c# - Async network operations never finish - Stack Overflow