TaskFactory::StartNew Method (Action^, CancellationToken)

.NET Framework (current version)

Creates and starts a Task.

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

Syntax

public:
Task^ StartNew(
	Action^ action,
	CancellationToken cancellationToken
)

Parameters

action: Type: System::Action^
The action delegate to execute asynchronously.

cancellationToken: Type: System.Threading::CancellationToken
The CancellationToken that will be assigned to the new task.

Return Value

Type: System.Threading.Tasks::Task^

The started Task.

Exceptions

Exception	Condition
ObjectDisposedException	The provided CancellationToken has already been disposed.
ArgumentNullException	The exception that is thrown when the action argument is null.

Remarks

Calling StartNew is functionally equivalent to creating a Task using one of its constructors and then calling Start to schedule it for execution.

Starting with the .NET Framework 4.5, you can use the Task::Run(Action^, CancellationToken) method as a quick way to call StartNew(Action^, CancellationToken) with default parameters. Note, however, that there is a difference in behavior between the two methods regarding : Task::Run(Action^, CancellationToken) by default does not allow child tasks started with the TaskCreationOptions::AttachedToParent option to attach to the current Task instance, whereas StartNew(Action^, CancellationToken) does. For more information and code examples, see Task.Run vs Task.Factory.StartNew in the Parallel Programming with .NET blog.

Examples

The following example calls the StartNew(Action^, CancellationToken) method to create a task that iterates the files in the C:\Windows\System32 directory. The lambda expression calls the Parallel::ForEach<TSource> method to add information about each file to a List<T> object. Each detached nested task invoked by the Parallel::ForEach<TSource> loop checks the state of the cancellation token and, if cancellation is requested, calls the CancellationToken::ThrowIfCancellationRequested method. The CancellationToken::ThrowIfCancellationRequested method throws an OperationCanceledException exception that is handled in a catch block when the calling thread calls the Task::Wait method.

C++

No code example is currently available or this language may not be supported.

Version Information

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