Pause/resume a thread in C#

Question

I try to pause all my threads when I reach a certain value but I can't do it.

I would like that when I reach this value all threads are paused for 10 seconds and after these 10 seconds all threads start again.

I tried that with : Threads.Sleep(); | Threads.Interrupt(); and Threads.Abort(); but nothing work.

I tried what you can see in the code below.

        static void Main(string[] args)
        {
            for (int i = 0; i < 10; i++)
            {
                Threads.Add(new Thread(new ThreadStart(example)));
                Threads[i].Start();
            }

            for (int i = 0; i < Threads.Count; i++)
                Threads[i].Join();
        }

        static void example()
        {           
            while (true)
            {
                Console.WriteLine(value++);
                checkValue();
            }
        }

        public static void checkValue()
        {
            if (value% 1000 == 0 && value!= 0)
            {
                for (int i = 0; i < Threads.Count; i++)
                    Threads[i].Interrupt();

                Thread.Sleep(1000);

                for (int i = 0; i < Threads.Count; i++)
                    Threads[i].Resume();
            }
        }

Have you tried the [`Suspend`](https://learn.microsoft.com/en-us/dotnet/api/system.threading.thread.suspend) and `Resume` methods? — Theodor Zoulias, Apr 29 '20 at 10:43
Also if pausing the threads cooperatively is an option, look at the pair [`PauseTokenSource`](http://dotnetapis.com/pkg/Nito.AsyncEx.Coordination/5.0.0/netstandard2.0/doc/Nito.AsyncEx.PauseTokenSource) + [`PauseToken`](http://dotnetapis.com/pkg/Nito.AsyncEx.Coordination/5.0.0/netstandard2.0/doc/Nito.AsyncEx.PauseToken) from Stephen Cleary's [AsyncEx.Coordination](https://www.nuget.org/packages/Nito.AsyncEx.Coordination/) package. — Theodor Zoulias, Apr 29 '20 at 10:59
I don't understand how AsyncEX works. Can you explain it to me please ? @TheodorZoulias — Fanfarone, Apr 29 '20 at 11:56

score 1 · Accepted Answer · answered Apr 29 '20 at 12:38

Here is an example of pausing some threads cooperatively, by using the PauseTokenSource + PauseToken pair from Stephen Cleary's AsyncEx.Coordination package. This example shows also the use of the analogous CancellationTokenSource + CancellationToken pair, that inspired the creation of the aforementioned pausing mechanism.

var pts = new PauseTokenSource() { IsPaused = true };
var cts = new CancellationTokenSource();
int value = 0;

// Create five threads
Thread[] threads = Enumerable.Range(1, 5).Select(i => new Thread(() =>
{
    try
    {
        while (true)
        {
            cts.Token.ThrowIfCancellationRequested(); // self explanatory
            pts.Token.WaitWhilePaused(cts.Token); // ...and don't wait if not paused
            int localValue = Interlocked.Increment(ref value);
            Console.WriteLine($"Thread #{i}, Value: {localValue}");
        }
    }
    catch (OperationCanceledException) // this exception is expected and benign
    {
        Console.WriteLine($"Thread #{i} Canceled");
    }
})).ToArray();

// Start the threads
foreach (var thread in threads) thread.Start();

// Now lets pause and unpause the threads periodically some times
// We use the main thread (the current thread) as the controller
Thread.Sleep(500);
pts.IsPaused = false;
Thread.Sleep(1000);
pts.IsPaused = true;
Thread.Sleep(1000);
pts.IsPaused = false;
Thread.Sleep(1000);
pts.IsPaused = true;
Thread.Sleep(500);

// Finally cancel the threads and wait them to finish
cts.Cancel();
foreach (var thread in threads) thread.Join();

You may need to read this first, to get a grasp on the model used by the .NET platform for cooperative cancellation. Cooperative "pausation" is very similar.

Pause/resume a thread in C#

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