What are semaphores in Python?

Can you explain what semaphores are in Python?

Sure! Semaphores are synchronization primitives that control access to a shared resource in concurrent programming.

How do semaphores work in Python?

In Python, semaphores are implemented using the threading module. They maintain a counter that represents the number of allowed accesses.

Can you give me an example of using semaphores?

Absolutely! Here's a simple example:

import threading
import time

semaphore = threading.Semaphore(2)  # Allow 2 threads to access the resource

def access_resource(thread_id):
    with semaphore:
        print(f'Thread {thread_id} is accessing the resource.')
        time.sleep(2)  # Simulate resource access
        print(f'Thread {thread_id} is done.')

threads = [threading.Thread(target=access_resource, args=(i,)) for i in range(5)]
for thread in threads:
    thread.start()
for thread in threads:
    thread.join()

What happens if more threads try to access the resource than allowed?

If more threads try to access the resource than the semaphore allows, they will be blocked until a slot becomes available.