What are some examples of semaphores in multithreading?

What are some examples of semaphores in multithreading?

Semaphores are synchronization tools used to control access to shared resources in multithreading. For example, a binary semaphore can be used to ensure that only one thread accesses a critical section of code at a time.

Can you give me a specific coding example?

Sure! In Python, you can use the threading module. Here's a simple example:

import threading

semaphore = threading.Semaphore(1)

def critical_section():
    with semaphore:
        # Only one thread can execute this block at a time
        print('Accessing critical section')

This ensures that only one thread can access the critical section at any given time.

What happens if a thread tries to access the critical section when it's locked?

If a thread tries to access the critical section while it's locked by another thread, it will be blocked until the semaphore is released. This prevents race conditions and ensures data integrity.

Are there different types of semaphores?

Yes, there are two main types of semaphores: binary semaphores, which can be either locked or unlocked, and counting semaphores, which allow a specified number of threads to access a resource simultaneously.