TL;DR; Unfortunately, there is no built-in solution yet (at time of writting, 2022), hence you are free to use and/or implement whatever fits your situation. Example An alternative is to use the CountDownLatch class. public class DatabaseTest { /** * Data limit */ private static final int DATA_LIMIT = 5; /** * Countdown latch */ … Read more
Futures Futures were introduced in Java 5 (2004). They’re basically placeholders for a result of an operation that hasn’t finished yet. Once the operation finishes, the Future will contain that result. For example, an operation can be a Runnable or Callable instance that is submitted to an ExecutorService. The submitter of the operation can use … Read more
From the API docs (emphasis added): Methods may return an instance of this value type when it’s likely that the result of their operations will be available synchronously and when the method is expected to be invoked so frequently that the cost of allocating a new Task<TResult> for each call will be prohibitive. There are … Read more
Although similar in general cases (“run and get results for many tasks”), each function has some specific functionality for other cases: asyncio.gather() Returns a Future instance, allowing high level grouping of tasks: import asyncio from pprint import pprint import random async def coro(tag): print(“>”, tag) await asyncio.sleep(random.uniform(1, 3)) print(“<“, tag) return tag loop = asyncio.get_event_loop() … Read more
You can access the Result property of the task, which will cause your thread to block until the result is available: string code = GenerateCodeAsync().Result; Note: In some cases, this might lead to a deadlock: Your call to Result blocks the main thread, thereby preventing the remainder of the async code to execute. You have … Read more
Array.forEach does not provide this nicety (oh if it would) but there are several ways to accomplish what you want: Using a simple counter function callback () { console.log(‘all done’); } var itemsProcessed = 0; [1, 2, 3].forEach((item, index, array) => { asyncFunction(item, () => { itemsProcessed++; if(itemsProcessed === array.length) { callback(); } }); }); … Read more
Concurrent and parallel are effectively the same principle as you correctly surmise, both are related to tasks being executed simultaneously although I would say that parallel tasks should be truly multitasking, executed “at the same time” whereas concurrent could mean that the tasks are sharing the execution thread while still appearing to be executing in … Read more
“don’t tell me about how I should just do it “the right way” or whatever” OK. but you should really do it the right way… or whatever ” I need a concrete example of how to make it block … WITHOUT freezing the UI. If such a thing is possible in JS.” No, it is … Read more
var inputs = events.Select(async ev => await ProcessEventAsync(ev)) .Select(t => t.Result) .Where(i => i != null) .ToList(); But this seems very weird to me, first of all the use of async and await in the select. According to this answer by Stephen Cleary I should be able to drop those. The call to Select is … Read more
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