C# 5.0 Programmer's Reference

Tasks ❘ 845
Parallel.For
The Parallel.For method takes as parameters a starting value, an ending value, and a delegate. It
invokes the delegate for each of the values between the starting value (including that value) and the
ending value (not including that value). The method blocks until all the calls to the delegate have
completed and then the code continues.
The following code shows how a program might invoke the FindFibonacci method with the
parameters 0, 1, 2, and 3.
Parallel.For(0, 4, FindFibonacci);
Parallel.ForEach
The Parallel.ForEach method takes as parameters an enumerable collection of values and a delegate.
The ForEach method invokes the delegate, passing it each of the parameter values. The method blocks
until all the calls to the delegate have completed.
The following code shows how a program might call the FindFibonacci method, passing it the
input parameters 0, 2, 4, 6, and 8.
int[] numbers = {0, 2, 4, 6, 8};
Parallel.ForEach(numbers, FindFibonacci);
Parallel.Invoke
The Parallel.Invoke method lets you invoke one or more possibly different delegates. It executes
the delegates, possibly on different threads, and blocks until they all complete.
The following code shows how a program might use Parallel.Invoke to execute the
ResetParameters, LoadGame, and BuildWorld methods in parallel.
Parallel.Invoke(ResetParameters, LoadGame, BuildWorld);
Tasks
The System.Threading.Tasks.Task class enables you to create threads and run them asynchronously.
The following table summarizes the Task class’s most useful properties.
Property
Exception
Factory
IsCanceled
Purpose
Returns an AggregateException object containing information about
any exceptions that caused the Task to end early.
Provides access to TaskFactory class methods that you can use to create
Tasks. (This is explained in more detail shortly.)
Returns true if the Task was canceled.
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