One major difference is in exception propagation. An exception, thrown inside an async Task method, gets stored in the returned Task object and remains dormant until the task gets observed via await task, task.Wait(), task.Result or task.GetAwaiter().GetResult(). It is propagated this way even if thrown from the synchronous part of the async method. Consider the … Read more
TL;DR Don’t use the pattern in the question where you get the promises, and then separately wait on them; instead, use Promise.all (at least for now): const [value1, value2] = await Promise.all([getValue1Async(), getValue2Async()]); While your solution does run the two operations in parallel, it doesn’t handle rejection properly if both promises reject. Details: Your solution … Read more
It seems to be best practice not to place multiple lines of business logic in the try body Actually I’d say it is. You usually want to catch all exceptions from working with the value: try { const createdUser = await this.User.create(userInfo); console.log(createdUser) // business logic goes here } catch (error) { console.error(error) // from … Read more
Acquiring a value via an async method: var result = Task.Run(() => asyncGetValue()).Result; Syncronously calling an async method Task.Run( () => asyncMethod()).Wait(); No deadlock issues will occur due to the use of Task.Run.
The problem here is that you are trying to await an array of promises rather than a Promise. This doesn’t do what you expect. When the object passed to await is not a Promise, await simply returns the value as-is immediately instead of trying to resolve it. So since you passed await an array (of … Read more
The whole idea behind Parallel.ForEach() is that you have a set of threads and each thread processes part of the collection. As you noticed, this doesn’t work with async–await, where you want to release the thread for the duration of the async call. You could “fix” that by blocking the ForEach() threads, but that defeats … Read more
Your sleep function does not work because setTimeout does not (yet?) return a promise that could be awaited. You will need to promisify it manually: function timeout(ms) { return new Promise(resolve => setTimeout(resolve, ms)); } async function sleep(fn, …args) { await timeout(3000); return fn(…args); } Btw, to slow down your loop you probably don’t want … Read more
Async prefix is a kind of wrapper for Promises. async function latestTime() { const bl = await web3.eth.getBlock(‘latest’); console.log(bl.timestamp); // Returns a primitive console.log(typeof bl.timestamp.then == ‘function’); //Returns false – not a promise return bl.timestamp; } Is the same as function latestTime() { return new Promise(function(resolve,success){ const bl = web3.eth.getBlock(‘latest’); bl.then(function(result){ console.log(result.timestamp); // Returns a … Read more
Here’s a workaround I found that works for all cases (including suspended dispatchers). It’s not my code and I’m still working to fully understand it, but it does work. It can be called using: customerList = AsyncHelpers.RunSync<List<Customer>>(() => GetCustomers()); Code is from here public static class AsyncHelpers { /// <summary> /// Execute’s an async Task<T> … Read more
The return value will always be a promise. If you don’t explicitly return a promise, the value you return will automatically be wrapped in a promise. async function increment(num) { return num + 1; } // Even though you returned a number, the value is // automatically wrapped in a promise, so we call // … Read more