我已经阅读了关于这方面的文档，我想我明白了。AutoResetEvent在代码通过event.WaitOne()时重置，但ManualResetEvent不会。
这对吗?
当前回答
摘自c# 3.0果壳书，由 约瑟夫Albahari
c#线程-免费电子书
ManualResetEvent是AutoResetEvent的变体。它的不同之处在于它不会在线程通过WaitOne调用后自动重置，因此功能类似于gate:调用Set打开gate，允许WaitOne在gate处通过任意数量的线程;调用Reset会关闭大门，可能会导致排队等候的人越来越多，直到下一个门被打开。
可以使用布尔值“gateOpen”字段(使用volatile关键字声明)结合“spin-sleep”来模拟此功能——重复检查标志，然后小睡一小段时间。
ManualResetEvents有时用于表示特定操作已完成，或线程已完成初始化并准备执行工作。
其他回答
是的。这就像收费站和门的区别。ManualResetEvent是门，需要手动关闭(重置)。AutoResetEvent是一个收费站，允许一辆车通过，在下一辆车通过之前自动关闭。
如果你想理解AutoResetEvent和ManualResetEvent，你需要理解的不是线程，而是中断!
. net希望尽可能地实现底层编程。
中断是在低级编程中使用的，它相当于一个信号从低电平变成高电平(反之亦然)。当这种情况发生时，程序中断其正常执行，并将执行指针移到处理此事件的函数上。
当中断发生时，要做的第一件事是重置它的状态，因为硬件是这样工作的:
a pin is connected to a signal and the hardware listen for it to change (the signal could have only two states). if the signal changes means that something happened and the hardware put a memory variable to the state happened (and it remain like this even if the signal change again). the program notice that variable change states and move the execution to a handling function. here the first thing to do, to be able to listen again this interrupt, is to reset this memory variable to the state not-happened.
这就是ManualResetEvent和AutoResetEvent之间的区别。 如果ManualResetEvent发生，我不重置它，下次发生时，我将无法收听它。
好吧，通常在同一个线程中添加2个答案不是一个好的做法，但我不想编辑/删除我之前的答案，因为它可以在另一种方式上有所帮助。
现在，我创建了一个更全面、更容易理解的控制台应用程序片段。
只需在两个不同的控制台上运行示例，并观察行为。你会对幕后发生的事情有更清楚的了解。
手动复位事件
using System;
using System.Threading;
namespace ConsoleApplicationDotNetBasics.ThreadingExamples
{
public class ManualResetEventSample
{
private readonly ManualResetEvent _manualReset = new ManualResetEvent(false);
public void RunAll()
{
new Thread(Worker1).Start();
new Thread(Worker2).Start();
new Thread(Worker3).Start();
Console.WriteLine("All Threads Scheduled to RUN!. ThreadId: {0}", Thread.CurrentThread.ManagedThreadId);
Console.WriteLine("Main Thread is waiting for 15 seconds, observe 3 thread behaviour. All threads run once and stopped. Why? Because they call WaitOne() internally. They will wait until signals arrive, down below.");
Thread.Sleep(15000);
Console.WriteLine("1- Main will call ManualResetEvent.Set() in 5 seconds, watch out!");
Thread.Sleep(5000);
_manualReset.Set();
Thread.Sleep(2000);
Console.WriteLine("2- Main will call ManualResetEvent.Set() in 5 seconds, watch out!");
Thread.Sleep(5000);
_manualReset.Set();
Thread.Sleep(2000);
Console.WriteLine("3- Main will call ManualResetEvent.Set() in 5 seconds, watch out!");
Thread.Sleep(5000);
_manualReset.Set();
Thread.Sleep(2000);
Console.WriteLine("4- Main will call ManualResetEvent.Reset() in 5 seconds, watch out!");
Thread.Sleep(5000);
_manualReset.Reset();
Thread.Sleep(2000);
Console.WriteLine("It ran one more time. Why? Even Reset Sets the state of the event to nonsignaled (false), causing threads to block, this will initial the state, and threads will run again until they WaitOne().");
Thread.Sleep(10000);
Console.WriteLine();
Console.WriteLine("This will go so on. Everytime you call Set(), ManualResetEvent will let ALL threads to run. So if you want synchronization between them, consider using AutoReset event, or simply user TPL (Task Parallel Library).");
Thread.Sleep(5000);
Console.WriteLine("Main thread reached to end! ThreadId: {0}", Thread.CurrentThread.ManagedThreadId);
}
public void Worker1()
{
for (int i = 1; i <= 10; i++)
{
Console.WriteLine("Worker1 is running {0}/10. ThreadId: {1}.", i, Thread.CurrentThread.ManagedThreadId);
Thread.Sleep(5000);
// this gets blocked until _autoReset gets signal
_manualReset.WaitOne();
}
Console.WriteLine("Worker1 is DONE. ThreadId: {0}", Thread.CurrentThread.ManagedThreadId);
}
public void Worker2()
{
for (int i = 1; i <= 10; i++)
{
Console.WriteLine("Worker2 is running {0}/10. ThreadId: {1}.", i, Thread.CurrentThread.ManagedThreadId);
Thread.Sleep(5000);
// this gets blocked until _autoReset gets signal
_manualReset.WaitOne();
}
Console.WriteLine("Worker2 is DONE. ThreadId: {0}", Thread.CurrentThread.ManagedThreadId);
}
public void Worker3()
{
for (int i = 1; i <= 10; i++)
{
Console.WriteLine("Worker3 is running {0}/10. ThreadId: {1}.", i, Thread.CurrentThread.ManagedThreadId);
Thread.Sleep(5000);
// this gets blocked until _autoReset gets signal
_manualReset.WaitOne();
}
Console.WriteLine("Worker3 is DONE. ThreadId: {0}", Thread.CurrentThread.ManagedThreadId);
}
}
}
自动重置事件
using System;
using System.Threading;
namespace ConsoleApplicationDotNetBasics.ThreadingExamples
{
public class AutoResetEventSample
{
private readonly AutoResetEvent _autoReset = new AutoResetEvent(false);
public void RunAll()
{
new Thread(Worker1).Start();
new Thread(Worker2).Start();
new Thread(Worker3).Start();
Console.WriteLine("All Threads Scheduled to RUN!. ThreadId: {0}", Thread.CurrentThread.ManagedThreadId);
Console.WriteLine("Main Thread is waiting for 15 seconds, observe 3 thread behaviour. All threads run once and stopped. Why? Because they call WaitOne() internally. They will wait until signals arrive, down below.");
Thread.Sleep(15000);
Console.WriteLine("1- Main will call AutoResetEvent.Set() in 5 seconds, watch out!");
Thread.Sleep(5000);
_autoReset.Set();
Thread.Sleep(2000);
Console.WriteLine("2- Main will call AutoResetEvent.Set() in 5 seconds, watch out!");
Thread.Sleep(5000);
_autoReset.Set();
Thread.Sleep(2000);
Console.WriteLine("3- Main will call AutoResetEvent.Set() in 5 seconds, watch out!");
Thread.Sleep(5000);
_autoReset.Set();
Thread.Sleep(2000);
Console.WriteLine("4- Main will call AutoResetEvent.Reset() in 5 seconds, watch out!");
Thread.Sleep(5000);
_autoReset.Reset();
Thread.Sleep(2000);
Console.WriteLine("Nothing happened. Why? Becasuse Reset Sets the state of the event to nonsignaled, causing threads to block. Since they are already blocked, it will not affect anything.");
Thread.Sleep(10000);
Console.WriteLine("This will go so on. Everytime you call Set(), AutoResetEvent will let another thread to run. It will make it automatically, so you do not need to worry about thread running order, unless you want it manually!");
Thread.Sleep(5000);
Console.WriteLine("Main thread reached to end! ThreadId: {0}", Thread.CurrentThread.ManagedThreadId);
}
public void Worker1()
{
for (int i = 1; i <= 5; i++)
{
Console.WriteLine("Worker1 is running {0}/5. ThreadId: {1}.", i, Thread.CurrentThread.ManagedThreadId);
Thread.Sleep(500);
// this gets blocked until _autoReset gets signal
_autoReset.WaitOne();
}
Console.WriteLine("Worker1 is DONE. ThreadId: {0}", Thread.CurrentThread.ManagedThreadId);
}
public void Worker2()
{
for (int i = 1; i <= 5; i++)
{
Console.WriteLine("Worker2 is running {0}/5. ThreadId: {1}.", i, Thread.CurrentThread.ManagedThreadId);
Thread.Sleep(500);
// this gets blocked until _autoReset gets signal
_autoReset.WaitOne();
}
Console.WriteLine("Worker2 is DONE. ThreadId: {0}", Thread.CurrentThread.ManagedThreadId);
}
public void Worker3()
{
for (int i = 1; i <= 5; i++)
{
Console.WriteLine("Worker3 is running {0}/5. ThreadId: {1}.", i, Thread.CurrentThread.ManagedThreadId);
Thread.Sleep(500);
// this gets blocked until _autoReset gets signal
_autoReset.WaitOne();
}
Console.WriteLine("Worker3 is DONE. ThreadId: {0}", Thread.CurrentThread.ManagedThreadId);
}
}
}
我创建了简单的示例来阐明ManualResetEvent与AutoResetEvent的理解。
AutoResetEvent:让我们假设你有3个工作线程。如果这些线程中的任何一个调用WaitOne()，所有其他两个线程将停止执行并等待信号。我假设他们正在使用WaitOne()。它就像;如果我不工作，没人会工作。在第一个例子中你可以看到
autoReset.Set();
Thread.Sleep(1000);
autoReset.Set();
当你调用Set()时，所有线程都将工作并等待信号。1秒后，我发送第二个信号，它们执行并等待(WaitOne())。想想这些家伙是足球队的球员，如果一个球员说我会等到经理叫我，其他人会等到经理告诉他们继续(Set())
public class AutoResetEventSample
{
private AutoResetEvent autoReset = new AutoResetEvent(false);
public void RunAll()
{
new Thread(Worker1).Start();
new Thread(Worker2).Start();
new Thread(Worker3).Start();
autoReset.Set();
Thread.Sleep(1000);
autoReset.Set();
Console.WriteLine("Main thread reached to end.");
}
public void Worker1()
{
Console.WriteLine("Entered in worker 1");
for (int i = 0; i < 5; i++) {
Console.WriteLine("Worker1 is running {0}", i);
Thread.Sleep(2000);
autoReset.WaitOne();
}
}
public void Worker2()
{
Console.WriteLine("Entered in worker 2");
for (int i = 0; i < 5; i++) {
Console.WriteLine("Worker2 is running {0}", i);
Thread.Sleep(2000);
autoReset.WaitOne();
}
}
public void Worker3()
{
Console.WriteLine("Entered in worker 3");
for (int i = 0; i < 5; i++) {
Console.WriteLine("Worker3 is running {0}", i);
Thread.Sleep(2000);
autoReset.WaitOne();
}
}
}
在这个例子中，你可以清楚地看到，当你第一次点击Set()时，它会让所有线程离开，然后在1秒后它会通知所有线程等待!一旦你再次设置它们，不管它们在里面调用WaitOne()，它们都会继续运行，因为你必须手动调用Reset()来停止它们。
manualReset.Set();
Thread.Sleep(1000);
manualReset.Reset();
Console.WriteLine("Press to release all threads.");
Console.ReadLine();
manualReset.Set();
这更多的是裁判和球员之间的关系，不管任何球员受伤了，等待比赛，其他人都将继续工作。如果裁判说等待(Reset())，那么所有球员将等待下一次信号。
public class ManualResetEventSample
{
private ManualResetEvent manualReset = new ManualResetEvent(false);
public void RunAll()
{
new Thread(Worker1).Start();
new Thread(Worker2).Start();
new Thread(Worker3).Start();
manualReset.Set();
Thread.Sleep(1000);
manualReset.Reset();
Console.WriteLine("Press to release all threads.");
Console.ReadLine();
manualReset.Set();
Console.WriteLine("Main thread reached to end.");
}
public void Worker1()
{
Console.WriteLine("Entered in worker 1");
for (int i = 0; i < 5; i++) {
Console.WriteLine("Worker1 is running {0}", i);
Thread.Sleep(2000);
manualReset.WaitOne();
}
}
public void Worker2()
{
Console.WriteLine("Entered in worker 2");
for (int i = 0; i < 5; i++) {
Console.WriteLine("Worker2 is running {0}", i);
Thread.Sleep(2000);
manualReset.WaitOne();
}
}
public void Worker3()
{
Console.WriteLine("Entered in worker 3");
for (int i = 0; i < 5; i++) {
Console.WriteLine("Worker3 is running {0}", i);
Thread.Sleep(2000);
manualReset.WaitOne();
}
}
}
简短的回答是肯定的。最重要的区别是AutoResetEvent只允许一个等待线程继续。另一方面，ManualResetEvent将继续允许线程，甚至同时允许几个线程继续，直到您告诉它停止(重置它)。
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