What is the difference between mutexes and semaphores?

What is the difference between mutexes and semaphores?

Mutexes and semaphores are both synchronization primitives used in concurrent programming, but they serve different purposes. A mutex (mutual exclusion) is used to protect shared resources from being accessed by multiple threads simultaneously, ensuring that only one thread can access the resource at a time. A semaphore, on the other hand, is a signaling mechanism that can allow multiple threads to access a limited number of resources. It maintains a count that represents the number of available resources.

Can you give an example of when to use a mutex?

Sure! You would use a mutex when you have a shared variable, like a counter, that multiple threads need to update. By locking the mutex before updating the counter, you ensure that only one thread can modify it at a time, preventing race conditions.

What about semaphores? When should I use them?

Semaphores are useful when you have a pool of resources, like a fixed number of database connections. You can use a semaphore to limit the number of threads that can access the database connections simultaneously, allowing for better resource management.

Are there any downsides to using mutexes or semaphores?

Yes, both can lead to issues like deadlocks if not managed properly. With mutexes, if two threads lock each other's mutexes, they can end up waiting indefinitely. Semaphores can also lead to resource starvation if some threads are consistently favored over others.