What are the differences between semaphores and condition variables?

What are the differences between semaphores and condition variables?

Semaphores and condition variables are both synchronization primitives used in concurrent programming, but they serve different purposes. Semaphores are used to control access to a resource by multiple threads, while condition variables are used for signaling between threads.

Can you explain how semaphores work?

Sure! A semaphore maintains a count that represents the number of available resources. When a thread wants to access a resource, it decrements the count. If the count is zero, the thread will block until a resource becomes available.

And what about condition variables?

Condition variables allow threads to wait for certain conditions to be true. A thread can wait on a condition variable, releasing the associated mutex, and another thread can signal the condition variable when the condition is met, waking up the waiting thread.

Are there any scenarios where one is preferred over the other?

Yes, semaphores are preferred when you need to limit access to a resource, while condition variables are better for situations where threads need to wait for specific conditions to proceed.