使用异步/等待时，GUI冻结 [英] GUI freezes when using async/await

问题描述

我正在尝试找出下面的代码出了什么问题.我以为使用async和await让我忘记了诸如冻结之类的GUI问题，因为一些长代码阻塞了主线程.

I'm trying to figure out what's wrong with the code below. I thought that using async and await lets me forget about GUI issues such as freezing because some long code is blocking the main thread.

单击按钮后，GUI会响应，直到调用 longRunningMethod ，如下所示:

After I click the button, the GUI is responsive until the call to longRunningMethod, as shown below:

 private async void openButton_Click(object sender, RoutedEventArgs e)
 {
    //doing some usual stuff before calling downloadFiles
    Task<int> result = await longRunningMethod(); // async method

    //at this point GUI becomes unresponsive

    //I'm using the result here, so I can't proceed until the longRunningMethod finishes

  }

在方法完成之前我无法继续，因为我需要 result .为什么这段代码会冻结我的应用程序?

I can't proceed until the method finishes, because I need the result. Why this code freezes my app?

推荐答案

问题出在 longRunningMethod 之内.

代码可能所执行的操作是某些CPU约束或阻塞操作.

What the code is probably doing is some CPU-bound or blocking operation.

如果要在后台线程上运行一些CPU绑定的代码，则必须显式地执行； async 不会自动跳转线程:

If you want to run some CPU-bound code on a background thread, you have to do so explicitly; async won't jump threads automatically:

int result = await Task.Run(() => longRunningMethod());

请注意，如果 longRunningMethod 受CPU限制，则应具有同步(而非异步)签名.

Note that if longRunningMethod is CPU-bound, it should have a synchronous - not asynchronous - signature.

如果 longRunningMethod 不是不是受CPU限制(即，它当前正在阻塞)，那么您需要在 longRunningMethod 中更改阻塞方法调用异步，然后通过 await 调用它们.然后，您可以使 longRunningMethod 异步并通过 await 进行调用:

If longRunningMethod is not CPU-bound (i.e., it's currently blocking), then you need to change the blocking method calls within longRunningMethod to be asynchronous, and call them via await. Then you can make longRunningMethod asynchronous and call it via await as well:

int result = await longRunningMethodAsync();

这篇关于使用异步/等待时，GUI冻结的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！