修改问题是-互斥量和“二进制”信号量在“Linux”中的区别是什么?

答:以下是它们的区别 i)作用域——互斥锁的作用域在创建它的进程地址空间内，用于线程同步。而信号量可以跨进程空间使用，因此它可以用于进程间同步。

ii)互斥量是轻量级的，比信号量更快。Futex甚至更快。

iii)同一线程可以成功多次获得互斥锁，条件是互斥锁释放次数相同。其他线程试图获取将阻塞。而对于信号量，如果同一个进程试图再次获取它，它会阻塞，因为它只能获得一次。

以上几乎所有人都说对了。如果有人还有疑问，让我来澄清一下。

互斥->用于序列化 信号- >同步。

两者的目的是不同的，但是，通过精心的编程，可以实现相同的功能。

标准示例->生产者消费者问题。

initial value of SemaVar=0

Producer                           Consumer
---                                SemaWait()->decrement SemaVar   
produce data
---
SemaSignal SemaVar or SemaVar++  --->consumer unblocks as SemVar is 1 now.

希望我能澄清。

互斥对象有所有权，不像信号量。尽管在互斥量范围内的任何线程都可以获得一个未锁定的互斥量，并锁定对同一关键代码段的访问，但只有锁定了互斥量的线程才应该解锁它。

互斥锁用于阻塞关键区域，而信号量用于计数。

既然上面的答案都不能消除困惑，这里有一个答案可以消除我的困惑。

Strictly speaking, a mutex is a locking mechanism used to synchronize access to a resource. Only one task (can be a thread or process based on OS abstraction) can acquire the mutex. It means there will be ownership associated with mutex, and only the owner can release the lock (mutex). Semaphore is signaling mechanism (“I am done, you can carry on” kind of signal). For example, if you are listening songs (assume it as one task) on your mobile and at the same time your friend called you, an interrupt will be triggered upon which an interrupt service routine (ISR) will signal the call processing task to wakeup.

来源:http://www.geeksforgeeks.org/mutex-vs-semaphore/

The basic issue is concurrency. There is more than one flow of control. Think about two processes using a shared memory. Now only one process can access the shared memory at a time. If more than one process accesses the shared memory at a time, the contents of shared memory would get corrupted. It is like a railroad track. Only one train can run on it, else there would be an accident.So there is a signalling mechanism, which a driver checks. If the signal is green, the train can go and if it is red it has to wait to use the track. Similarly in case of shared memory, there is a binary semaphore. If the semaphore is 1, a process acquires it (makes it 0) and goes ahead and accesses it. If the semaphore is 0, the process waits. The functionality the binary semaphore has to provide is mutual exclusion (or mutex, in short) so that only one of the many concurrent entities (process or thread) mutually excludes others. It is a plus that we have counting semaphores, which help in synchronizing multiple instances of a resource.

互斥是信号量提供的基本功能。现在在线程上下文中，我们可能有不同的名称和语法。但基本概念是相同的:如何在并发编程中保持代码和数据的完整性。在我看来，像所有权和相关检查这样的东西是由实现提供的改进。