There are two common use cases I’ve found: When you’re implementing an interface that allows asynchronous callers, but your implementation is synchronous. When you’re stubbing/mocking asynchronous code for testing.
Figured it out, the task should look like: namespace :test do task :new_task => :environment do puts Parent.all.inspect end end Notice the => :environment dependency added to the task
There is one sneaky case when return in normal method and return await in async method behave differently: when combined with using (or, more generally, any return await in a try block). Consider these two versions of a method: Task<SomeResult> DoSomethingAsync() { using (var foo = new Foo()) { return foo.DoAnotherThingAsync(); } } async Task<SomeResult> … Read more
After you use WhenAll, you can pull the results out individually with await: var catTask = FeedCat(); var houseTask = SellHouse(); var carTask = BuyCar(); await Task.WhenAll(catTask, houseTask, carTask); var cat = await catTask; var house = await houseTask; var car = await carTask; You can also use Task.Result (since you know by this point … Read more
Note the guidelines for performing work on a UI thread, collected on my blog: Don’t block the UI thread for more than 50ms at a time. You can schedule ~100 continuations on the UI thread per second; 1000 is too much. There are two techniques you should use: 1) Use ConfigureAwait(false) when you can. E.g., … Read more
Thread is a lower-level concept: if you’re directly starting a thread, you know it will be a separate thread, rather than executing on the thread pool etc. Task is more than just an abstraction of “where to run some code” though – it’s really just “the promise of a result in the future”. So as … Read more
If you want to get the exception “asynchronously”, you could do: MyAsyncMethod(). ContinueWith(t => Console.WriteLine(t.Exception), TaskContinuationOptions.OnlyOnFaulted); This will allow you to deal with an exception on a thread other than the “main” thread. This means you don’t have to “wait” for the call to MyAsyncMethod() from the thread that calls MyAsyncMethod; but, still allows you … Read more