C# Async without framework functions

Question

I have a method which is run n times with different parameters, simplified:

foreach(var param in params)
    ValueList.Add(SomeMethod(param));

I would like to do this:

foreach(var param in params)
    TaskList.Add(SomeMethodAsync(param));

foreach(var task in TaskList)
    ValueList.Add(await task);

async Task<SomeValue> SomeMethodAsync(SomeParam p)
{
     //What to do here
     //To make this call async
     return SomeMethod(p);
}

How do I have to modify the current Method to apply the async functionality? The SomeMethod does not use any framework-functions that provide async; it is fully synchronous.

To describe it in different words: I want n tasks of this method to run asynchronously/simultaneously using the new async/await keywords.

You may want to read Should I expose asynchronous wrappers for synchronous methods. Also, your second foreach loop can be replaced with var valueList = await Task.WhenAll(taskList);. — Stephen Cleary
– Stephen Cleary, Commented Nov 13, 2012 at 13:18
As I wrote in a comment below; In my case, I am communicating with 14 different servers at once (not webrequest or other async-able operations), there are no resources being used on the client end; I simply need to wait for all operations to finish. However, it seems to take equally long for the sum of operations, no matter if I do Parrallel.ForEach, Jobs.AsParallel.Select(x => SomeMethod(x)) or when I use Tasks. (actually Tasks took a little bit longer than the rest) The sum of time is well above the individual operation timeout time. — Manuel Schweigert
– Manuel Schweigert, Commented Nov 13, 2012 at 13:27
It seems the underlying framework blocks the queries internally, I have no other explanation for the behaviour. — Manuel Schweigert
– Manuel Schweigert, Commented Nov 14, 2012 at 18:48

Cameron MacFarland · Accepted Answer · 2012-11-13 12:06:06Z

2

If your method does not return an asynchronous result then there's no point using async/await.

If you just want to run your methods in parallel, use Parallel.ForEach

Parallel.ForEach(params, param => ValueList.Add(SomeMethod(param)));

If SomeMethod does not use a task, or await any framework async calls then it will run on a single thread, regardless of whether you add async to the method definition.

Your best option in that case is to run SomeMethod in a task.

async Task<SomeValue> SomeMethodAsync(SomeParam p)
{
    return await Task.Run<SomeValue>(() => SomeMethod(p));
}

Personally I think the Parallel.ForEach is clearer.

edited Nov 13, 2012 at 12:06

answered Nov 13, 2012 at 11:22

Cameron MacFarland

72.2k20 gold badges107 silver badges134 bronze badges

Sign up to request clarification or add additional context in comments.

6 Comments

Boas Enkler Over a year ago

True, but you should be aware that this introduces a new thread. Async doesn't necesseraly introduce new thread. You can use any kind of Task<T> for awaiting.

Cameron MacFarland Over a year ago

@BoasEnkler True, although the default task scheduler uses the thread pool instead of always spinning up a new task. But if the point is to run them in series and they block, async ain't gonna help.

Boas Enkler Over a year ago

Yes also true :-) But I thought more about concurrency and data race issues in general. So the code should be thread safe. And some behavior may change. Depending on the scenario

Cameron MacFarland Over a year ago

Yes I was a bit worried about what type ValueList is, and if it's not a threadsafe list there might be issues.

Manuel Schweigert Over a year ago

Maybe I explained it wrong; I want to know what I have to change in said method to make it work with async/await. Clarified the question.

|

L.B · Accepted Answer · 2012-11-13 11:54:40Z

1

Just make it a function returning task.

Task<SomeValue> SomeMethodAsync(SomePAram p)
{
    return Task<SomeValue>.Run(()=> SomeMethod());
}

SomeMethodAsync is awaitable now.

answered Nov 13, 2012 at 11:54

L.B

116k20 gold badges189 silver badges229 bronze badges

2 Comments

Cameron MacFarland Over a year ago

you need to add the await keyword after the return otherwise the compiler complains that the return value must be of type SomeValue instead of Task<SomeValue>.

L.B Over a year ago

@CameronMacFarland No , See the method declaration there is no async

Collectives™ on Stack Overflow

C# Async without framework functions

2 Answers 2

6 Comments

2 Comments

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

2 Answers 2

6 Comments

2 Comments

Your Answer

Sign up or log in

Post as a guest

Related