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Parallel.ForEach<TSource> Method (IEnumerable<TSource>, ParallelOptions, Action<TSource>)

.NET Framework 4.6 and 4.5

Executes a foreach (For Each in Visual Basic) operation on an IEnumerable in which iterations may run in parallel and loop options can be configured.

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

public static ParallelLoopResult ForEach<TSource>(
	IEnumerable<TSource> source,
	ParallelOptions parallelOptions,
	Action<TSource> body


Type: System.Collections.Generic.IEnumerable<TSource>

An enumerable data source.

Type: System.Threading.Tasks.ParallelOptions

An object that configures the behavior of this operation.

Type: System.Action<TSource>

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 data in the source.

Exception Condition

The CancellationToken in the parallelOptions argument is canceled


The source argument is null.


The parallelOptions argument is null.


The body argument is null.


The exception that contains all the individual exceptions thrown on all threads.


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

The body delegate is invoked once for each element in the source enumerable. It is provided with the current element as a parameter.

Universal Windows Platform
Available since 4.5
.NET Framework
Available since 4.0
Portable Class Library
Supported in: portable .NET platforms
Windows Phone
Available since 8.1
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