我如何让我的c#程序睡眠(暂停执行)50毫秒?
System.Threading.Thread.Sleep(50);
记住,在主GUI线程中这样做会阻碍GUI的更新(它会感觉“迟缓”)。
只要把;使它也适用于VB.net。
Thread.Sleep(50);
在指定的时间内,操作系统不会调度线程执行。该方法将线程的状态更改为包含WaitSleepJoin。
此方法不执行标准的COM和SendMessage抽取。 如果您需要在具有STAThreadAttribute的线程上休眠,但又希望执行标准COM和SendMessage泵送,请考虑使用指定超时间隔的Join方法的一个重载。
Thread.Join
在Windows中无法指定确切的睡眠时间。你需要一个实时的操作系统。最好的方法是指定一个最小睡眠时间。然后由调度器在此之后唤醒线程。永远不要在GUI线程上调用. sleep()。
在(几乎)任何编程语言中,等待基本上有3种选择:
Loose waiting Executing thread blocks for given time (= does not consume processing power) No processing is possible on blocked/waiting thread Not so precise Tight waiting (also called tight loop) processor is VERY busy for the entire waiting interval (in fact, it usually consumes 100% of one core's processing time) Some actions can be performed while waiting Very precise Combination of previous 2 It usually combines processing efficiency of 1. and preciseness + ability to do something of 2.
为1。c#中的松散等待:
Thread.Sleep(numberOfMilliseconds);
然而,windows线程调度器导致Sleep()的准确性在15ms左右(所以Sleep可以很容易地等待20ms,即使计划只等待1ms)。
为2。c#中的紧等待是:
Stopwatch stopwatch = Stopwatch.StartNew();
while (true)
{
//some other processing to do possible
if (stopwatch.ElapsedMilliseconds >= millisecondsToWait)
{
break;
}
}
我们也可以使用DateTime。现在或其他方式的时间测量,但秒表是快得多(这将真正成为在紧循环)。
为3。——组合:
Stopwatch stopwatch = Stopwatch.StartNew();
while (true)
{
//some other processing to do STILL POSSIBLE
if (stopwatch.ElapsedMilliseconds >= millisecondsToWait)
{
break;
}
Thread.Sleep(1); //so processor can rest for a while
}
这段代码会定期阻塞线程1ms(或者稍微多一点,这取决于操作系统线程调度),所以处理器在阻塞期间并不繁忙,代码也不会消耗处理器100%的功耗。其他处理仍然可以在阻塞之间执行(例如:更新UI,处理事件或做交互/通信之类的事情)。
既然现在你有了async/await特性,那么最好的睡眠50ms的方法就是使用Task。延迟:
async void foo()
{
// something
await Task.Delay(50);
}
或者如果你的目标是。net 4(使用VS2010的Async CTP 3或Microsoft.Bcl.Async),你必须使用:
async void foo()
{
// something
await TaskEx.Delay(50);
}
这样你就不会阻塞UI线程。
两全其美:
using System.Runtime.InteropServices;
[DllImport("winmm.dll", EntryPoint = "timeBeginPeriod", SetLastError = true)]
private static extern uint TimeBeginPeriod(uint uMilliseconds);
[DllImport("winmm.dll", EntryPoint = "timeEndPeriod", SetLastError = true)]
private static extern uint TimeEndPeriod(uint uMilliseconds);
/**
* Extremely accurate sleep is needed here to maintain performance so system resolution time is increased
*/
private void accurateSleep(int milliseconds)
{
//Increase timer resolution from 20 miliseconds to 1 milisecond
TimeBeginPeriod(1);
Stopwatch stopwatch = new Stopwatch();//Makes use of QueryPerformanceCounter WIN32 API
stopwatch.Start();
while (stopwatch.ElapsedMilliseconds < milliseconds)
{
//So we don't burn cpu cycles
if ((milliseconds - stopwatch.ElapsedMilliseconds) > 20)
{
Thread.Sleep(5);
}
else
{
Thread.Sleep(1);
}
}
stopwatch.Stop();
//Set it back to normal.
TimeEndPeriod(1);
}
从.NET Framework 4.5开始,你可以使用:
using System.Threading.Tasks;
Task.Delay(50).Wait(); // wait 50ms