Stopping HttpListener doesn't free up address in use for some time on macOS (System.Net.HttpListenerException: Address already in use) #24025

TylerLeonhardt · 2017-11-02T16:53:49Z

I'm receiving the following error:

Unhandled Exception: System.Net.HttpListenerException: Address already in use
   at System.Net.HttpEndPointManager.GetEPListener(String host, Int32 port, HttpListener listener, Boolean secure)
   at System.Net.HttpEndPointManager.AddPrefixInternal(String p, HttpListener listener)
   at System.Net.HttpEndPointManager.AddListener(HttpListener listener)
   at System.Net.HttpListener.Start()
   at TestHttpListener.TestHttpListener.<SimpleListenerExample>d__3.MoveNext() in /Users/tylerleonhardt/Desktop/CompSci/DotNET/Core/TestHttpListener/TestHttpListener.cs:line 29
--- End of stack trace from previous location where exception was thrown ---
   at System.Runtime.ExceptionServices.ExceptionDispatchInfo.Throw()
   at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task)
   at TestHttpListener.TestHttpListener.<>c__DisplayClass1_0.<<Start>b__0>d.MoveNext() in /Users/tylerleonhardt/Desktop/CompSci/DotNET/Core/TestHttpListener/TestHttpListener.cs:line 13
--- End of stack trace from previous location where exception was thrown ---
   at System.Runtime.ExceptionServices.ExceptionDispatchInfo.Throw()
   at System.Threading.ExecutionContext.Run(ExecutionContext executionContext, ContextCallback callback, Object state)
   at System.Threading.ThreadPoolWorkQueue.Dispatch()

I am writing an http server using HttpListener (I need to use HttpListener) and I run into this exception after starting and stoping and starting the server.

Here is my (watered down) library:

using System;
using System.Net;
using System.Threading;
using System.Threading.Tasks;

namespace TestHttpListener
{
    public class TestHttpListener
    {
        public bool KeepGoing = true;
        public void Start(int Port)
        {
            Thread listenerThread = new Thread(async () => { await SimpleListenerExample(Port); });
            listenerThread.Start();
        }

        public void Stop()
        {
            KeepGoing = false;
        }

        public async Task SimpleListenerExample(int Port)
        {
            // Create a listener.
            HttpListener listener = new HttpListener();
            // Add the prefixes.
            listener.Prefixes.Add("http://localhost:" + Port + "/");

            listener.Start();
            Console.WriteLine("Listening...");

            while (KeepGoing)
            {
                // Note: The GetContext method blocks while waiting for a request.
                HttpListenerContext context = await listener.GetContextAsync();
                HttpListenerRequest request = context.Request;
                // Obtain a response object.
                HttpListenerResponse response = context.Response;

                // Construct a response.
                string responseString = "<HTML><BODY> Hello world!</BODY></HTML>";
                byte[] buffer = System.Text.Encoding.UTF8.GetBytes(responseString);
                // Get a response stream and write the response to it.
                response.ContentLength64 = buffer.Length;
                System.IO.Stream output = response.OutputStream;
                output.Write(buffer,0,buffer.Length);
                // You must close the output stream.
                output.Close();
            }

            listener.Stop();
        }
    }
}

I've also tried this with listener.Close()

And the file I'm using to verify this behavior is:

using System;
using System.Net.Http;
using System.Threading.Tasks;

namespace TestHttpListener
{
    class Program
    {
        private static readonly HttpClient client = new HttpClient();
        static void Main(string[] args)
        {
            Run().Wait();
        }

        static async Task Run()
        {
            var app = new TestHttpListener();
            app.Start(8081);
            await Task.Delay(TimeSpan.FromSeconds(2));
            var response = await client.GetAsync("http://localhost:8081");
            app.Stop();
            // need second GetAsync becuase HttpListener GetContextAsync does not take a cancellation token
            response = await client.GetAsync("http://localhost:8081");
            await Task.Delay(TimeSpan.FromSeconds(2));
            app.Start(8081);
            Console.ReadLine();
        }
    }
}

I noticed there was this issue with "Address already in use" issues but it seemed unrelated to HttpListener class so I opened this.

This is using the .NET Command Line Tools - 2.0.0
macOS - v10.12.6 (16G29) aka Sierra

Please let me know if there's any additional info I can provide.

The text was updated successfully, but these errors were encountered:

TylerLeonhardt · 2017-11-02T16:54:21Z

This issue does not repro on Windows with .NET Framework.

PeterSmithRedmond · 2017-11-03T00:23:40Z

Without being a macOs network expert, my first thought is that you are running into TIME_WAIT and MSL issues. This is a good StackOverflow discussion of what they mean.

When you close a connection, the OS waits "a while" for any stray packets that might have been delayed on the network to either arrive (and be thrown out) or to time out on the network (which also involves them being thrown out). In all case, we don't want those stray packets to arrive on the destination machine and possibly be considered to be part of an new connection!

The amount of time the OS will wait is 2*msl. According to this ServerFault post, MSL on macOs Lion is 15 seconds. That implies that you have to wait for at least 30 seconds to reuse the server port.

Can you try either bumping up the time, or switching the port to different values?

TylerLeonhardt · 2017-11-03T02:56:41Z

I appreciate this. However, I'm wondering how frameworks like Node.js Express.js and ASP.NET Core are handing this. I'm able to stop and start their webservers without any issue. Why does it work for those but not HttpListener on .NET Core?

stephentoub · 2017-11-03T02:59:38Z

Presumably this is https://github.com/dotnet/corefx/issues/24562 / dotnet/corefx#24809
cc: @tmds

TylerLeonhardt · 2017-11-10T08:00:32Z

I thought it might be related to those but wasn't sure since those didn't mention HttpListener. Is this then a dupe of one of those, you think?

tmds · 2017-11-10T09:03:30Z

@tylerl0706 yes, I believe that is the root cause of the issue you are seeing.

stephentoub · 2017-11-14T16:53:29Z

Dup of #23803 / dotnet/corefx#24809. Thanks for reporting.

…ps://github.com/dotnet/corefx/issues/25016

dhowe · 2018-05-10T14:02:52Z

Apologies if I missed it above, but is there a fix for this issue with HttpListener on OS X?

bgottfried91 · 2018-05-24T19:35:49Z

@dhowe , can't speak for OS X, but the issue appears to be fixed in the latest dotnet core 2.1 Debian release (tested against docker image microsoft/dotnet:2.1-runtime). Try switching to the 2.1 framework and see if it resolves the issue for you on OS X.

TylerLeonhardt · 2018-05-24T21:24:54Z

Haven't messed with this in some time so I'm good. 👍

dhowe · 2018-05-24T21:28:20Z

Unless something has changed very recently, this is issue is NOT resolved. I have since switched to debian where the issue (as @bgottfried91 mentions above) does not appear to exist. On OSX the only workaround I had found was to use random ports.

tmds · 2018-05-25T06:48:17Z

@dhowe are you using 2.1?

dhowe · 2018-05-25T07:02:52Z

dotnet 2.0 due to compatibility requirements

tmds · 2018-05-25T07:34:35Z

The fix is not in 2.0. Using 2.1 you shouldn't see this. 2.1 will be released soon-ish.

stephentoub closed this as completed Nov 14, 2017

robertruetz referenced this issue in robertruetz/MamaBird Apr 12, 2018

Switched from HttpListener to WebListener in hopes of solving for htt…

fff7096

…ps://github.com/dotnet/corefx/issues/25016

msftgits transferred this issue from dotnet/corefx Jan 31, 2020

msftgits added this to the 2.1.0 milestone Jan 31, 2020

jchristn mentioned this issue Oct 14, 2020

Disposing WatsonWSServer doesn't free port jchristn/WatsonWebsocket#38

Closed

dotnet locked as resolved and limited conversation to collaborators Dec 19, 2020

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Stopping HttpListener doesn't free up address in use for some time on macOS (System.Net.HttpListenerException: Address already in use) #24025

Stopping HttpListener doesn't free up address in use for some time on macOS (System.Net.HttpListenerException: Address already in use) #24025

TylerLeonhardt commented Nov 2, 2017

TylerLeonhardt commented Nov 2, 2017

PeterSmithRedmond commented Nov 3, 2017

TylerLeonhardt commented Nov 3, 2017

stephentoub commented Nov 3, 2017

TylerLeonhardt commented Nov 10, 2017

tmds commented Nov 10, 2017

stephentoub commented Nov 14, 2017

dhowe commented May 10, 2018

bgottfried91 commented May 24, 2018 •

edited

TylerLeonhardt commented May 24, 2018 •

edited

dhowe commented May 24, 2018 •

edited

tmds commented May 25, 2018

dhowe commented May 25, 2018

tmds commented May 25, 2018

Stopping HttpListener doesn't free up address in use for some time on macOS (System.Net.HttpListenerException: Address already in use) #24025

Stopping HttpListener doesn't free up address in use for some time on macOS (System.Net.HttpListenerException: Address already in use) #24025

Comments

TylerLeonhardt commented Nov 2, 2017

TylerLeonhardt commented Nov 2, 2017

PeterSmithRedmond commented Nov 3, 2017

TylerLeonhardt commented Nov 3, 2017

stephentoub commented Nov 3, 2017

TylerLeonhardt commented Nov 10, 2017

tmds commented Nov 10, 2017

stephentoub commented Nov 14, 2017

dhowe commented May 10, 2018

bgottfried91 commented May 24, 2018 • edited

TylerLeonhardt commented May 24, 2018 • edited

dhowe commented May 24, 2018 • edited

tmds commented May 25, 2018

dhowe commented May 25, 2018

tmds commented May 25, 2018

bgottfried91 commented May 24, 2018 •

edited

TylerLeonhardt commented May 24, 2018 •

edited

dhowe commented May 24, 2018 •

edited