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C# Task.Delay()和Thread.Sleep()有什么区别?

寒冰屋 发布时间:2022-09-08 19:15:00 ,浏览量:7

很多时候我们需要做一段延时处理,就直接Thread.Sleep(n)处理了,但实际上延时也可以用Task.Delay(n),那二者之间有没有区别呢?

我们先来看一个案例:


using System;
using System.Threading;
using System.Threading.Tasks;

namespace ConsoleApp22
{
    class Program
    {
        static void Main(string[] args)
        {
            //Good writing
            Task.Run(async () =>
            {
                int delayTimeCount = 0;
                while (true)
                {
                    Console.WriteLine($"Delay第{++delayTimeCount}秒");
                    await Task.Delay(1000);
                }
            });

            //Bad writing
            Task.Run(() =>
            {
                int sleepTimeCount = 0;
                while (true)
                {
                    Console.WriteLine($"Thread{++sleepTimeCount}秒");
                    Thread.Sleep(1000);
                }
            });

            Console.ReadKey();
        }
    }
}

运行结果:

区别:

①.Thread.Sleep()是同步延迟,既然是同步的,自然会阻塞当前线程;Task.Delay()是异步延迟,则不会阻塞线程; ②.Thread.Sleep()不能中途取消,Task.Delay()可以,delay有四个重载方法,需要取消的话,可以调用Delay(int millisecondsDelay, CancellationToken cancellationToken)这个方法;

        //
        // 摘要:
        //     Creates a task that completes after a specified number of milliseconds.
        //
        // 参数:
        //   millisecondsDelay:
        //     The number of milliseconds to wait before completing the returned task, or -1
        //     to wait indefinitely.
        //
        // 返回结果:
        //     A task that represents the time delay.
        //
        // 异常:
        //   T:System.ArgumentOutOfRangeException:
        //     The millisecondsDelay argument is less than -1.
        public static Task Delay(int millisecondsDelay);
        //
        // 摘要:
        //     Creates a cancellable task that completes after a specified number of milliseconds.
        //
        // 参数:
        //   millisecondsDelay:
        //     The number of milliseconds to wait before completing the returned task, or -1
        //     to wait indefinitely.
        //
        //   cancellationToken:
        //     A cancellation token to observe while waiting for the task to complete.
        //
        // 返回结果:
        //     A task that represents the time delay.
        //
        // 异常:
        //   T:System.ArgumentOutOfRangeException:
        //     The millisecondsDelay argument is less than -1.
        //
        //   T:System.Threading.Tasks.TaskCanceledException:
        //     The task has been canceled.
        //
        //   T:System.ObjectDisposedException:
        //     The provided cancellationToken has already been disposed.
        public static Task Delay(int millisecondsDelay, CancellationToken cancellationToken);
        //
        // 摘要:
        //     Creates a task that completes after a specified time interval.
        //
        // 参数:
        //   delay:
        //     The time span to wait before completing the returned task, or TimeSpan.FromMilliseconds(-1)
        //     to wait indefinitely.
        //
        // 返回结果:
        //     A task that represents the time delay.
        //
        // 异常:
        //   T:System.ArgumentOutOfRangeException:
        //     delay represents a negative time interval other than TimeSpan.FromMilliseconds(-1).
        //     -or- The delay argument's System.TimeSpan.TotalMilliseconds property is greater
        //     than System.Int32.MaxValue.
        public static Task Delay(TimeSpan delay);
        //
        // 摘要:
        //     Creates a cancellable task that completes after a specified time interval.
        //
        // 参数:
        //   delay:
        //     The time span to wait before completing the returned task, or TimeSpan.FromMilliseconds(-1)
        //     to wait indefinitely.
        //
        //   cancellationToken:
        //     A cancellation token to observe while waiting for the task to complete.
        //
        // 返回结果:
        //     A task that represents the time delay.
        //
        // 异常:
        //   T:System.ArgumentOutOfRangeException:
        //     delay represents a negative time interval other than TimeSpan.FromMilliseconds(-1).
        //     -or- The delay argument's System.TimeSpan.TotalMilliseconds property is greater
        //     than System.Int32.MaxValue.
        //
        //   T:System.Threading.Tasks.TaskCanceledException:
        //     The task has been canceled.
        //
        //   T:System.ObjectDisposedException:
        //     The provided cancellationToken has already been disposed.
        public static Task Delay(TimeSpan delay, CancellationToken cancellationToken);

③在异步代码中通常使用await关键字调用Task.Delay(),而不是Thread.Sleep();

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