Watching Asynchronous Operation Execution Status

C# Tutorials - Herong's Tutorial Examples

∟Watching Asynchronous Operation Execution Status

A tutorial example is provided on how to query the 'Status' property to watch the execution status of an asynchronous operation. The tutorial example shows 5 asynchronous operations running in 5 child threads.

In order to demonstrate the asynchronously of the GetStringAsync() method from the HttpClient class, I wrote another tutorial example program, MultipleAsyncTasks.cs, that starts 5 GetStringAsync() calls and watches their progresses:

// MultipleAsyncTasks.cs
// Copyright (c) 2016 HerongYang.com. All Rights Reserved.

using System;
using System.Net.Http;
using System.Threading;
using System.Threading.Tasks;
public class MultipleAsyncTasks {
   static void Main() {
      string[] sites = new string[5];
      sites[0] = "https://www.herongyang.com/Service/Hello_REST.php";
      sites[1] = "http://www.microsoft.com";
      sites[2] = "http://www.google.com";
      sites[3] = "http://www.faceboot.com";
      sites[4] = "http://www.twitter.com";

      // Launch 5 asynchronous tasks
      HttpClient c = new HttpClient();
      Task<string>[] tasks = new Task<string>[5];
      for (int i=0; i<5; i++) {
         tasks[i] = c.GetStringAsync(sites[i]);
      }

      // Watch their progresses
      bool wait = true;
      int w = 0;
      Console.WriteLine("Time, herongyang.com, microsft.com,"
         +" google.com, facebook, twitter.com");
      while (wait && w<=10000) {
         wait = false;
         string msg = "" + w;
         for (int i=0; i<5; i++) {
            TaskStatus s = tasks[i].Status;
            wait = wait || (s!=TaskStatus.RanToCompletion);
            msg = msg+", "+tasks[i].Status;
         }
         Console.WriteLine(msg);
         int t = 100;
         Thread.Sleep(t);
         w += t;
      }
   }
}

Execution output is list below with .NET Framework 4.6.1 SDK:

C:\herong>%NET%\csc "/r:%REF%/System.Net.Http.dll"
   MultipleAsyncTasks.cs
Microsoft (R) Visual C# Compiler version 4.6.1055.0
for C# 5

C:\herong>MultipleAsyncTasks
Time, herongyang.com, microsft.com, google.com, facebook, twitter.com
0, WaitingForActivation (WFA), WFA, WFA, WFA, WFA
100, WFA, WFA, WFA, WFA, WFA
200, WFA, WFA, WFA, WFA, WFA
300, WFA, WFA, WFA, WFA, WFA
400, RanToCompletion (RTC), WFA, WFA, WFA, WFA
500, RTC, RTC, WFA, WFA, WFA
600, RTC, RTC, WFA, WFA, WFA
700, RTC, RTC, WFA, WFA, WFA
800, RTC, RTC, WFA, WFA, WFA
900, RTC, RTC, RTC, WFA, WFA
1000, RTC, RTC, RTC, WFA, WFA
1100, RTC, RTC, RTC, WFA, WFA
1200, RTC, RTC, RTC, WFA, WFA
1300, RTC, RTC, RTC, WFA, WFA
1400, RTC, RTC, RTC, WFA, WFA
1500, RTC, RTC, RTC, WFA, WFA
1600, RTC, RTC, RTC, WFA, WFA
1700, RTC, RTC, RTC, WFA, WFA
1800, RTC, RTC, RTC, RTC, WFA
1900, RTC, RTC, RTC, RTC, WFA
2000, RTC, RTC, RTC, RTC, WFA
...
4800, RTC, RTC, RTC, RTC, WFA
4900, RTC, RTC, RTC, RTC, RTC

Excellent! Now we can see asynchronous operation in "slow" motion. Interesting notes about this example program:

My Web site performed better than Microsoft, Google, Facebook and Twitter. It returned the HTTP response in 0.4 seconds.
Twitter Web site was the worst performer. It took about 5.0 seconds to the HTTP response!
It's very interesting to see that the tasks were in "WaitingForActivation" status before turning into "RanToCompletion" status. Should they be in "Running" status instead of "WaitingForActivation"?