What are the differences between semaphore and lock in Python?

What are the differences between semaphore and lock in Python?

In Python, a lock is a synchronization primitive that allows only one thread to access a resource at a time, while a semaphore can allow multiple threads to access a resource up to a specified limit.

Can you give an example of when to use a semaphore instead of a lock?

Sure! Use a semaphore when you want to limit access to a resource, like a database connection pool, where you want to allow a certain number of concurrent connections.

Are there any performance differences between using a semaphore and a lock?

Yes, semaphores can be more efficient in scenarios where multiple threads can work concurrently, while locks can lead to contention and performance bottlenecks if many threads are waiting for access.

How do I implement a semaphore in Python?

You can implement a semaphore in Python using the threading module. Here's a simple example:

import threading

semaphore = threading.Semaphore(3)  # Allow 3 threads to access the resource

def access_resource():
    with semaphore:
        # Critical section
        print('Accessing resource')

This code allows up to 3 threads to access the resource simultaneously.