Wait for any task and return the task if the condition is met. Otherwise wait again for the other tasks until there is no more task to wait for. public static async Task<Task> WhenAny( IEnumerable<Task> tasks, Predicate<Task> condition ) { var tasklist = tasks.ToList(); while ( tasklist.Count > 0 ) { var task = await … Read more
this.startRequest is a delegate that points to StartRequest which in turn uses HttpWebRequest.BeginGetResponse to start async IO. HttpClient is using async IO under the covers, just wrapped in a thread-pool Task. That said, note the following comment in SendAsync // BeginGetResponse/BeginGetRequestStream have a lot of setup work to do before becoming async // (proxy, dns, … Read more
This is not Task Chaining. You need to do Task chaining using ContinueWith. Last task would need to update the UI. Task.Factory.StartNew( () => DoThis()) .ContinueWith((t1) => DoThat()) .ContinueWith((t2) => UpdateUi(), TaskScheduler.FromCurrentSynchronizationContext()); Note the last line has TaskScheduler.FromCurrentSynchronizationContext() this will ensure task will run in the synchronization context (UI Thread).
You absolutely want to use FromAsync when an API offers a BeginXXX/EndXXX version of a method. The difference is that, in the case of something like Stream or Socket or WebRequest, you’ll actually end up using async I/O underneath the covers (e.g. I/O Completion Ports on Windows) which is far more efficient than blocking multiple … Read more
You’re not leveraging any async I/O APIs in any of your code. Everything you’re doing is CPU bound and all your I/O operations are going to waste CPU resources blocking. AsParallel is for compute bound tasks, if you want to take advantage of async I/O you need to leverage the Asynchronous Programming Model (APM) based … Read more
There are two possible approaches. The first would be to inherit from a concurrent collection and add INotifyCollectionChanged functionality, and the second would be to inherit from a collection that implements INotifyCollectionChanged and add concurrency support. I think it is far easier and safer to add INotifyCollectionChanged support to a concurrent collection. My suggestion is … Read more
What about this: await Task.WhenAll(tasks1); var gainStrings = tasks1.Select(t => t.Result).ToList(); Wait for all tasks to end and then extract results. This is ideal if you don’t care in which order they are finished. EDIT2: Even better way: var gainStrings = await Task.WhenAll(tasks1);
The issue is exactly what casperOne said in his answer. Once the first transform block completes, the processor block goes into “finishing mode”: it will process remaining items in its input queue, but it won’t accept any new items. There is a simpler fix than splitting your processor block in two though: don’t set PropagateCompletion, … Read more
I just gave an answer which is very applicable to this question. Basically, the TPL Task class is made to schedule CPU-bound work. It is not made for blocking work. You are working with a resource that is not CPU: waiting for service replies. This means the TPL will mismange your resource because it assumes … Read more
Incidentally, I am just reading Concurrency in C# CookBook, by Stephen Cleary, and I can refer to some parts of the book here, I guess. From Recipe 2.5 – Discussion, we have When the first task completes, consider whether to cancel the remaining tasks. If the other tasks are not canceled but are also never … Read more