什么是互斥体？
互斥锁（实际上，互斥锁是互斥的简称），也称为自旋锁（spinlock），是最简单的同步工具，用于保护关键区域并因此防止竞争状况。那就是线程在进入临界区之前必须获得锁（在临界区中，多个线程共享一个公共变量，更新表，写入文件等），它在离开临界区时释放该锁。
什么是比赛条件？
当两个或多个线程可以访问共享数据并且它们试图同时更改它们时，就会发生竞争状态。因为线程调度算法可以随时在线程之间交换，所以您不知道线程尝试访问共享数据的顺序。因此，数据更改的结果取决于线程调度算法，即两个线程都在“竞争”访问/更改数据。
现实生活中的例子：
当我在工作中进行激烈的讨论时，我会使用橡皮鸡，这种情况下我会把它放在桌子上。抱着鸡的人是唯一被允许说话的人。如果你不抱鸡，你就不会说话。您只能指出自己想要这只鸡，然后等到收到它再说。说完之后，您可以将鸡交给主持人，主持人将把鸡交给下一个要发言的人。这样可以确保人们不会互相讲话，也没有自己的交谈空间。
用Mutex替换Chicken并用线程替换person，您基本上就有了互斥锁的概念。
@Xetius
在C＃中的用法：
本示例说明如何使用本地互斥对象来同步对受保护资源的访问。因为每个调用线程在获得互斥体的所有权之前都是被阻塞的，所以必须调用ReleaseMutex方法来释放线程的所有权。
using System;
using System.Threading;
class Example
{
// Create a new Mutex. The creating thread does not own the mutex.
private static Mutex mut = new Mutex();
private const int numIterations = 1;
private const int numThreads = 3;
static void Main()
{
// Create the threads that will use the protected resource.
for(int i = 0; i < numThreads; i++)
{
Thread newThread = new Thread(new ThreadStart(ThreadProc));
newThread.Name = String.Format("Thread{0}", i + 1);
newThread.Start();
}
// The main thread exits, but the application continues to
// run until all foreground threads have exited.
}
private static void ThreadProc()
{
for(int i = 0; i < numIterations; i++)
{
UseResource();
}
}
// This method represents a resource that must be synchronized
// so that only one thread at a time can enter.
private static void UseResource()
{
// Wait until it is safe to enter.
Console.WriteLine("{0} is requesting the mutex",
Thread.CurrentThread.Name);
mut.WaitOne();
Console.WriteLine("{0} has entered the protected area",
Thread.CurrentThread.Name);
// Place code to access non-reentrant resources here.
// Simulate some work.
Thread.Sleep(500);
Console.WriteLine("{0} is leaving the protected area",
Thread.CurrentThread.Name);
// Release the Mutex.
mut.ReleaseMutex();
Console.WriteLine("{0} has released the mutex",
Thread.CurrentThread.Name);
}
}
// The example displays output like the following:
// Thread1 is requesting the mutex
// Thread2 is requesting the mutex
// Thread1 has entered the protected area
// Thread3 is requesting the mutex
// Thread1 is leaving the protected area
// Thread1 has released the mutex
// Thread3 has entered the protected area
// Thread3 is leaving the protected area
// Thread3 has released the mutex
// Thread2 has entered the protected area
// Thread2 is leaving the protected area
// Thread2 has released the mutex
MSDN参考互斥