. Net4.0 Parallel programming (iii) under Data Parallelism

In the previous article, we introduced how to Break and Stop loops, and how to define local variables of a thread. This article describes how to cancel loops and handle exceptions externally.

Cancel

In a parallel loop, you can pass the aspx> CancellationToken in the ParallelOptions parameter to cancel loop control. We can pass CancellationTokenSource to the Cancellation value of the ParallelOptions object after instantiation. The following is an example:

 

01	[TestMethod]

02	public void CancelLoop()

03

{

04	var sourceNums = Enumerable.Range(0, 1000000000);

05	var cts = new CancellationTokenSource();

06	var po = new ParallelOptions();

07	var stack = new ConcurrentStack<int>();

08	po.CancellationToken = cts.Token;

09	po.MaxDegreeOfParallelism = System.Environment.ProcessorCount;

10	Task.Factory.StartNew(() =>

11

{

12	foreach (var num in sourceNums)

13

{

14	if (num == 1000000)

15	cts.Cancel();

16

}

17

});

18

19

try

20

{

21	Parallel.ForEach(sourceNums,po, num =>

22

{

23	stack.Push(num);

24	po.CancellationToken.ThrowIfCancellationRequested();

25