中止并行

Question

I'm using Parallel.ForEach for achieving parallelism, I was wondering is there any way that I can stop the execution of Parallel.ForEach once any one the requests complete. For example consider the following code:

IEnumerable<string> myList = new List<string>() { "admin", "admin2", "admin3" };
CancellationTokenSource _tokenSource = new CancellationTokenSource();

Parallel.ForEach(myList,
    admin_name =>
    {
        Console.WriteLine(admin_name);
    });

The above code prints admin , admin2 and admin3 . I want to stop further execution if any of the admin names is printed.

Is this achievable? Or is there any work around available?

I am open to suggestions and improvement.

Answer 1

There is an overload of Parallel.ForEach which passes a ParallelLoopState to your delegate, this can be use to break out of the Parallel.ForEach , ie:

Parallel.ForEach(myList, (admin_name, state) => 
{
    Console.WriteLine(admin_name);

    // Stop other iterations
    state.Stop();
});

What you will need to bear in mind is that this will not be atomic, other delegates which have already started will continue to execute, unless they explicitly check state.IsStopped .

Instead of ParallelLoopState.Stop() you may desire ParallelLoopState.Break() .

Some further information about Stop() and Break() can be found at How to: Stop or Break from a Parallel.For Loop .