concurrency - Semaphores/Creating a Critical Section

Question

How can you use a semaphore to create a special critical section that allows two threads to be executing inside instead of the usual one thread?

Answer 1

在伪代码中它看起来像这样：

s = Semaphore(2)    # max 2 possible threads accessing the critical section

然后每个线程使用信号量来序列化访问：

s.decrement()    # may block 
    # enter critical section
s.increment()

有用的资源是：信号量小书