Parallel::ForEach<TSource> Method (Partitioner<TSource>^, ParallelOptions^, Action<TSource, ParallelLoopState^>^)

.NET Framework (current version)

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Executes a foreach (For Each in Visual Basic) operation on a Partitioner in which iterations may run in parallel, loop options can be configured, and the state of the loop can be monitored and manipulated.

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

generic<typename TSource>
static ParallelLoopResult ForEach(
	Partitioner<TSource>^ source,
	ParallelOptions^ parallelOptions,
	Action<TSource, ParallelLoopState^>^ body


Type: System.Collections.Concurrent::Partitioner<TSource>^

The partitioner that contains the original data source.

Type: System.Threading.Tasks::ParallelOptions^

An object that configures the behavior of this operation.

Type: System::Action<TSource, ParallelLoopState^>^

The delegate that is invoked once per iteration.

Return Value

Type: System.Threading.Tasks::ParallelLoopResult

A structure that contains information about which portion of the loop completed.

Type Parameters


The type of the elements in source.

Exception Condition

The CancellationToken in the parallelOptions argument is canceled.


The CancellationTokenSource associated with the CancellationToken in the parallelOptions has been disposed.


The source argument is null.


The parallelOptions argument is null.


The body argument is null.


The SupportsDynamicPartitions property in the source partitioner returns false.


The exception that is thrown when any methods in the source partitioner return null.

This overload is provided for scenarios where you want to override the default partitioning scheme. For example, small loop bodies might benefit from partitioning the range. The Parallel::ForEach<TSource> method expects custom partitioners to support dynamic partitioning. For more information, see Custom Partitioners for PLINQ and TPL and How to: Implement Dynamic Partitions.

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