async-await

问题 I want to run a service that requests urls using coroutines and multithread. However I cannot pass coroutines to the workers in the executor. See the code below for a minimal example of this issue: import time import asyncio import concurrent.futures EXECUTOR = concurrent.futures.ThreadPoolExecutor(max_workers=5) async def async_request(loop): await asyncio.sleep(3) def sync_request(_): time.sleep(3) async def main(loop): futures = [loop.run_in_executor(EXECUTOR, async_request,loop) for x in

问题 I want to build a program that collects weather updates and represents them as a stream. I want to call get_weather() in an infinite loop, with 60 seconds delay between finish and start . A simplified version would look like this: async fn get_weather() -> Weather { /* ... */ } fn get_weather_stream() -> impl futures::Stream<Item = Weather> { loop { tokio::timer::delay_for(std::time::Duration::from_secs(60)).await; let weather = get_weather().await; yield weather; // This is not supported //

问题 I'm trying to understand why the following code: async void Handle_Clicked(object sender, System.EventArgs e) { try { await CrashAsync("aaa"); } catch (Exception exception) { Log($"observed exception"); Log($"Exception: {exception.Message}"); } } private async Task CrashAsync(string title) { Log($"CrashAsync ({title}) - before"); await Task.Delay(1000); throw new Exception($"CrashAsync ({title})"); Log($"CrashAsync ({title}) - after"); } produces the expected result: thread #1: CrashAsync

问题 static async void SendTweetWithSinglePicture(string message, string image) { var auth = new SingleUserAuthorizer { CredentialStore = new SingleUserInMemoryCredentialStore { ConsumerKey = "", ConsumerSecret = "", AccessToken = "", AccessTokenSecret = "" } }; var context = new TwitterContext(auth); var uploadedMedia = await context.UploadMediaAsync(File.ReadAllBytes(@image)); var mediaIds = new List<ulong> { uploadedMedia.MediaID }; await context.TweetAsync( message, mediaIds ); } protected

问题 I have found the following example in Jon Skeet's "C# in depth. 3rd edition": static async Task<int> GetPageLengthAsync(string url) { using (HttpClient client = new HttpClient()) { Task<string> fetchTextTask = client.GetStringAsync(url); int length = (await fetchTextTask).Length; return length; } } public static void Main() { Task<int> lengthTask = GetPageLengthAsync("http://csharpindepth.com"); Console.WriteLine(lengthTask.Result); } I expected that this code would deadlock, but it does not.

问题 I'm writing a discord bot using discord.py rewrite, and I want to run a function every day at a certain time. I'm not experienced with async functions at all and I can't figure out how to run one without using "await." This is only a piece of my code which is why some things may not be defined. async def send_channel(): try: await active_channel.send('daily text here') except Exception: active_channel_id = None active_channel = None async def timer(): while True: schedule.run_pending() await

问题 Data bindings don't get updated if their values are changed after an await statement. handle() { this.message = 'Works' } async handle() { this.message = 'Works' } async handle() { await new Promise((resolve, reject) => { resolve() }) this.message = 'Works' } async handle() { await new Promise((resolve, reject) => { setTimeout(() => resolve(), 3000) }) this.message = 'Doesn\'t work' } handle() { new Promise((resolve, reject) => { setTimeout(() => resolve(), 3000) }) .then(() => this.message =

问题 I'm using Parse as a data store for an app, and I am implementing their Facebook Login functionality. AFAIK, this Login method isn't any different than other async methods so hopefully it applies. So there is a Login.xaml page, that has a button for "Login with Facebook", and tapping this button takes you to the FacebookLogin.xaml page which contains only the WebBrowser control as per the linked Parse documenation. In ContentPanel.Loaded on FacebookLogin.xaml, I can use the following code to

问题 The following asynchronous xUnit.net test with a lambda marked with the async modifier fails by reporting that no exception was thrown: [Theory, AutoWebData] public async Task SearchWithNullQueryThrows( SearchService sut, CancellationToken dummyToken) { // Fixture setup // Exercise system and verify outcome Assert.Throws<ArgumentNullException>(async () => await sut.SearchAsync(null, dummyToken)); // Teardown } To make sure that an ArgumentNullException is actually thrown I explicitly used a

问题 I'm writing a WinForms application that transfers data to a USB HID class device. My application uses the excellent Generic HID library v6.0 which can be found here. In a nutshell, when I need to write data to the device, this is the code that gets called: private async void RequestToSendOutputReport(List<byte[]> byteArrays) { foreach (byte[] b in byteArrays) { while (condition) { // we'll typically execute this code many times until the condition is no longer met Task t =