Execute parallel tasks with async/await

Question

I need to execute multiple async tasks in Silverlight.

Documentation of the 3rd party package states I can use

await Task.WhenAll()

Unfortunately silverlight only have Task.WaitAll() and it is not awaitable. If I try to use it I get deadlock (I assume - because whole thing freezes)

What is the proper pattern to use in async method?

That should be the other way around. It's `WaitAll` that should be excluded from the silverlight API and WhenAll should be included. Do you have the proper version of .NET installed? — Servy, Mar 13 '13 at 03:58
FWIW, on my stock SL5 I only see `Task.WaitAll`; there is no `Task.WhenAll` I assume unless I install some 3rd party library. — Peter Tirrell, Jun 10 '16 at 15:47

score 11 · Accepted Answer · answered Mar 13 '13 at 04:27

11

For Silverlight I assume you're using the Microsoft.Bcl.Async package.

Since this (add-on) package cannot modify the (built-in) Task type, you'll find some useful methods in the TaskEx type. Including WhenAll:

await TaskEx.WhenAll(...);

answered Mar 13 '13 at 04:27

Stephen Cleary

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score 1 · Answer 2 · answered Mar 13 '13 at 04:10

I think that you could try to use TaskFactory.ContinueWhenAll to have similar behaviour if I understand your question correctly. Example:

var task1 = Task.Factory.StartNew(() =>
{
    Thread.Sleep(1000);
    return "dummy value 1";
});

var task2 = Task.Factory.StartNew(() =>
{
    Thread.Sleep(2000);
    return "dummy value 2";
});

var task3 = Task.Factory.StartNew(() =>
{
    Thread.Sleep(3000);
    return "dummy value 3";
});

Task.Factory.ContinueWhenAll(new[] { task1, task2, task3 }, tasks =>
{
    foreach (Task<string> task in tasks)
    {
        Console.WriteLine(task.Result);
    }
});

Execute parallel tasks with async/await

2 Answers2

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