任务与线程差异 [英] Task vs Thread differences

问题描述

我是并行编程的新手..NET 中有两个可用的类:Task 和 Thread.

I'm new to parallel programming. There are two classes available in .NET: Task and Thread.

所以，我的问题是:

• 这些类之间有什么区别?
• 什么时候使用 Thread 而不是 Task 更好(反之亦然)?

• What is the difference between those classes?
• When is it better to use Thread over Task (and vice-versa)?

推荐答案

Thread 是一个低级概念:如果你直接启动一个线程，你知道它将是一个单独的线程，而不是在线程池等上执行.

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 不仅仅是在何处运行某些代码"的抽象——它实际上只是对未来结果的承诺".举一些不同的例子:

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 some different examples:

• Task.Delay 不需要任何实际的 CPU 时间；这就像设置一个定时器在未来关闭
• WebClient.DownloadStringTaskAsync 返回的任务在本地不会占用太多 CPU 时间；它代表的结果可能大部分时间都花在网络延迟或远程工作上(在网络服务器上)
• Task.Run() 返回的任务确实 在说我希望你单独执行这段代码"；执行该代码的确切线程取决于多种因素.

• Task.Delay doesn't need any actual CPU time; it's just like setting a timer to go off in the future
• A task returned by WebClient.DownloadStringTaskAsync won't take much CPU time locally; it's representing a result which is likely to spend most of its time in network latency or remote work (at the web server)
• A task returned by Task.Run() really is saying "I want you to execute this code separately"; the exact thread on which that code executes depends on a number of factors.

请注意，Task 抽象对于 C# 5 中的异步支持至关重要.

Note that the Task<T> abstraction is pivotal to the async support in C# 5.

一般来说，我建议您尽可能使用更高级别的抽象:在现代 C# 代码中，您应该很少需要显式启动自己的线程.

In general, I'd recommend that you use the higher level abstraction wherever you can: in modern C# code you should rarely need to explicitly start your own thread.

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