CODEWITHSUNDEEP
c#multithreading
Nico Schreiner
Nico Schreiner

Reputation: 437

How to start two parallel threads from one object?

Let's say I have an object with one method that is constantly running. I already created a new thread running this method:

new Thread(new ThreadStart(myObject.firstMethod)).Start();

Now, I have a secondMethod in myObject that I want to start. Keep in mind that the previously strarted thread isn't terminated because firstMethod contains a Loop.

How can I start the second method? Do I need to create a second Thread?

Upvotes: 2

Views: 144

Answers (1)

TheGeneral
TheGeneral

Reputation: 81483

Its kind of unclear what you are asking or what you are exactly trying to achieve, however here is an example using Task running 2 endless loops (until a cancellation token is called)

public static void Method1(CancellationToken token)
{
      Task.Run(
         async () =>
         {
            while (!token.IsCancellationRequested)
            {
               // do something
               await Task.Delay(500, token); // <- await with cancellation
               Console.WriteLine("Method1");
            }
         }, token);
}

public static void Method2(CancellationToken token)
{
      Task.Run(
         async () =>
            {
               while (!token.IsCancellationRequested)
               {
                  // do something
                  await Task.Delay(300, token); // <- await with cancellation
                  Console.WriteLine("Method2");
               }
            }, token);
}

private static void Main(string[] args)
{
   var source = new CancellationTokenSource();  
   Method1(source.Token);
   Method2(source.Token);
   source.CancelAfter(3000);
   Console.ReadKey();
}

Demo Here

Task vs Thread differences

Thread is a lower-level concept: if you're directly starting a thread, you know it will be a separate thread, rather than executing on the thread pool etc.

Task is more than just an abstraction of "where to run some code" though - it's really just "the promise of a result in the future". So as some different examples:

  • Task.Delay doesn't need any actual CPU time; it's just like setting a timer to go off in the future
  • A task returned by WebClient.DownloadStringTaskAsync won't take much CPU time locally; it's representing a result which is likely to spend most of its time in network latency or remote work (at the web server)
  • A task returned by Task.Run() really is saying "I want you to execute this code separately"; the exact thread on which that code executes depends on a number of factors.

Note that the Task<T> abstraction is pivotal to the async support in C# 5.

In general, I'd recommend that you use the higher level abstraction wherever you can: in modern C# code you should rarely need to explicitly start your own thread.

Quote Jon Skeet

Upvotes: 2

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