Task.Run Method (Action)

.NET Framework 4.5

Queues the specified work to run on the ThreadPool and returns a task handle for that work.

Namespace:  System.Threading.Tasks
Assembly:  mscorlib (in mscorlib.dll)

public static Task Run(
	Action action


Type: System.Action

The work to execute asynchronously

Return Value

Type: System.Threading.Tasks.Task
A task that represents the work queued to execute in the ThreadPool.


The action parameter was null.

The Run method is a simpler alternative to the StartNew method. It creates a task with the following default values:

The following example illustrates the Run(Action) method. It defines an array of directory names and starts a separate task to retrieve the file names in each directory. All tasks write the file names to a single ConcurrentBag<T> object. The example then calls the WaitAll(Task[]) method to ensure that all tasks have completed, and then displays a count of the total number of file names written to the ConcurrentBag<T> object.

using System;
using System.Collections.Concurrent;
using System.Collections.Generic;
using System.IO;
using System.Threading.Tasks;

public class Example
   public static void Main()
      var list = new ConcurrentBag<string>();
      string[] dirNames = { ".", ".." };
      List<Task> tasks = new List<Task>();
      foreach (var dirName in dirNames) {
         Task t = Task.Run( () => { foreach(var path in Directory.GetFiles(dirName)) 
                                       list.Add(path); }  );
      foreach (Task t in tasks)
         Console.WriteLine("Task {0} Status: {1}", t.Id, t.Status);

      Console.WriteLine("Number of files read: {0}", list.Count);
// The example displays output like the following: 
//       Task 1 Status: RanToCompletion 
//       Task 2 Status: RanToCompletion 
//       Number of files read: 23

.NET Framework

Supported in: 4.5

.NET for Windows Store apps

Supported in: Windows 8

.NET for Windows Phone apps

Supported in: Windows Phone 8.1, Windows Phone Silverlight 8.1, Windows Phone Silverlight 8

Windows Phone 8.1, Windows Phone 8, Windows 8.1, Windows Server 2012 R2, Windows 8, Windows Server 2012, Windows 7, Windows Vista SP2, Windows Server 2008 (Server Core Role not supported), Windows Server 2008 R2 (Server Core Role supported with SP1 or later; Itanium not supported)

The .NET Framework does not support all versions of every platform. For a list of the supported versions, see .NET Framework System Requirements.

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