What is a replacement method for Task.Run in .NET 4.0 using C#?

Question

I got this program that gives me syntax error "System.Threading.Tasks.task does not contain a definition for Run."

I am using VB 2010 .NET 4.0 Any ideas? any replacements for Run in .net 4.0?

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading;
using System.Threading.Tasks;

namespace ChatApp
{
class ChatProg
{
    static void Main(string[] args)
    {
        Task<int> wakeUp = DoWorkAsync(2000,"Waking up");
        Task.WaitAll(wakeUp);
    }

    static Task<int> DoWorkAsync(int milliseconds, string name)
    {

        //error appears below on word Run
        return Task.Run(() =>
            {
                Console.WriteLine("* starting {0} work", name);
                Thread.Sleep(milliseconds);
                Console.WriteLine("* {0} work one", name);
                return 1;
            });
    }
}
}

Try this Task.Factory.StartNew() Please refer below link :http://blogs.msdn.com/b/pfxteam/archive/2011/10/24/10229468.aspx — Saroop Trivedi, Jul 12 '13 at 03:49
i got same issue but the problem that it has risk while i am reading about this issue so is threading good choose insted??? if yes please provide me with details example about threading because this my first time working with thread — sam, Dec 20 '16 at 08:33

McGarnagle · Accepted Answer · 2015-09-10T17:05:12.797

89

It looks like Task.Factory.StartNew<T> is what you're after.

return Task.Factory.StartNew<int>(() => {
    // ...
    return 1;
});

Since the compiler can infer the return type, this also works:

return Task.Factory.StartNew(() => {
    // ...
    return 1;
});

edited Sep 10 '15 at 17:05

answered Jul 12 '13 at 03:42

McGarnagle

101,349
31
229
260

2

Is Run a .NET 4.5 feature? – Ace Caserya Jul 12 '13 at 03:51
3

@Henryyottabyte yes, apparently: http://msdn.microsoft.com/en-us/library/system.threading.tasks.task.run.aspx – McGarnagle Jul 12 '13 at 03:52
3

adding to the answer is this link i found. http://blogs.msdn.com/b/pfxteam/archive/2011/10/24/10229468.aspx – Ace Caserya Jul 12 '13 at 03:53
1

It looks like Task::Factory->StartNew in C++/CLI – Miroslav Nedyalkov Dec 02 '14 at 17:43
5

It's important to know that this code does not behave identically to Task.Run. – usr May 30 '16 at 15:43

score 10 · Answer 2 · edited May 23 '17 at 10:31

The highest voted answer, unfortunately, is not exactly correct:

Unfortunately, the only overloads for StartNew that take a TaskScheduler also require you to specify the CancellationToken and TaskCreationOptions. This means that in order to use Task.Factory.StartNew to reliably, predictably queue work to the thread pool, you have to use an overload like this:

Task.Factory.StartNew(A, CancellationToken.None, TaskCreationOptions.DenyChildAttach, TaskScheduler.Default);

So the closest thing to Task.Run in 4.0 is something like:

/// <summary>
/// Starts the new <see cref="Task"/> from <paramref name="function"/> on the Default(usually ThreadPool) task scheduler (not on the TaskScheduler.Current).
/// It is a 4.0 method nearly analogous to 4.5 Task.Run.
/// </summary>
/// <typeparam name="T">The type of the return value.</typeparam>
/// <param name="factory">The factory to start from.</param>
/// <param name="function">The function to execute.</param>
/// <returns>The task representing the execution of the <paramref name="function"/>.</returns>
public static Task<T> StartNewOnDefaultScheduler<T>(this TaskFactory factory, Func<T> function)
{
    Contract.Requires(factory != null);
    Contract.Requires(function != null);

    return factory
        .StartNew(
            function,
            cancellationToken: CancellationToken.None,
            creationOptions: TaskCreationOptions.None,
            scheduler: TaskScheduler.Default);
}

that can be used like:

Task
    .Factory
    .StartNewOnDefaultScheduler(() => 
        result);

score 5 · Answer 3 · answered Jul 12 '13 at 03:53

I changed your code with Task.Factory.StartNew check detail link

 static Task<int> DoWorkAsync(int milliseconds, string name)
        {


            //error appears below on word Run
            return   Task.Factory.StartNew(() =>
            {
                Console.WriteLine("* starting {0} work", name);
                Thread.Sleep(milliseconds);
                Console.WriteLine("* {0} work one", name);
                return 1;
            });
        }

score 3 · Answer 4 · answered Aug 01 '18 at 06:45

3

In case you're using Microsoft.Bcl.Async here you go:

return TaskEx.Run(() =>
{
    Console.WriteLine("* starting {0} work", name);
    Thread.Sleep(milliseconds);
    Console.WriteLine("* {0} work one", name);
    return 1;
});

answered Aug 01 '18 at 06:45

Karmakulov Kirill

101
3

What is a replacement method for Task.Run in .NET 4.0 using C#?

4 Answers4

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