What is the functioning of Semaphore in Python?

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In Python, a Semaphore is a synchronization primitive used to control access to shared resources. It allows multiple threads to access shared resources while ensuring that only a specific number of threads can access the shared resources at a time. Semaphore works by maintaining internal counters and blocking or releasing threads based on the counter value.

The functioning of Semaphore in Python can be summarized in three major steps:

1. Initialization: In Python, a Semaphore is initialized with a value that represents the maximum number of threads that can access the shared resource simultaneously. The Semaphore can be initialized using the Semaphore constructor method.

2. Acquire and Release: Once a Semaphore is initialized, threads can acquire locks on the resource by calling the acquire() method. When a thread acquires a lock, the Semaphore's internal counter is decremented, and the thread is allowed to access the shared resource. Once the thread is finished with the resource, it calls the release() method, which increments the Semaphore's internal counter, indicating that the resource is free.

3. Blocking and Non-Blocking: A Semaphore can either block or not block threads that call the acquire() method. If a Semaphore is instantiated with a value of 1, it becomes a binary Semaphore that blocks threads. When a thread tries to acquire a lock and the Semaphore's internal counter is 0, the thread is blocked until the Semaphore's internal counter is incremented. If the Semaphore is instantiated with a value greater than 1, it becomes a counting Semaphore that does not block threads. When a thread tries to acquire a lock and the Semaphore's internal counter is 0, the thread continues to execute without blocking, but the Semaphore's internal counter is still decremented.