TaskFactory(Of TResult).StartNew Method (Func(Of TResult), CancellationToken, TaskCreationOptions, TaskScheduler)


The .NET API Reference documentation has a new home. Visit the .NET API Browser on docs.microsoft.com to see the new experience.

Creates and starts a task.

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

Public Function StartNew (
	function As Func(Of TResult),
	cancellationToken As CancellationToken,
	creationOptions As TaskCreationOptions,
	scheduler As TaskScheduler
) As Task(Of TResult)


Type: System.Func(Of TResult)

A function delegate that returns the future result to be available through the task.

Type: System.Threading.CancellationToken

The cancellation token that will be assigned to the new task.

Type: System.Threading.Tasks.TaskCreationOptions

One of the enumeration values that controls the behavior of the created task.

Type: System.Threading.Tasks.TaskScheduler

The task scheduler that is used to schedule the created task.

Return Value

Type: System.Threading.Tasks.Task(Of TResult)

The started task.

Exception Condition

The cancellation token source that createdcancellationToken has already been disposed.


The function argument is null.


The scheduler argument is null.


The creationOptions parameter specifies an invalid value.

Calling StartNew is functionally equivalent to creating a task by using one of the Task(Of TResult) constructors and then calling the Start method to schedule it for execution.

However, unless creation and scheduling must be separated, StartNew is the recommended approach for both simplicity and performance.

Universal Windows Platform
Available since 8
.NET Framework
Available since 4.0
Portable Class Library
Supported in: portable .NET platforms
Available since 5.0
Windows Phone Silverlight
Available since 8.0
Windows Phone
Available since 8.1
Return to top