What are the differences between mutex and spinlock in C++?

What are the differences between mutex and spinlock in C++?

Mutex and spinlock are both synchronization primitives used in C++. A mutex allows only one thread to access a resource at a time, putting other threads to sleep until the mutex is released. In contrast, a spinlock keeps checking the lock in a loop (spinning) until it becomes available, which can be more efficient for short wait times.

When should I use a mutex instead of a spinlock?

You should use a mutex when you expect longer wait times, as it puts threads to sleep, saving CPU resources. Use a spinlock for short critical sections where the wait time is minimal, as it avoids the overhead of context switching.

Are there any performance implications of using one over the other?

Yes, using a spinlock can lead to higher CPU usage if threads spin for too long, while mutexes can introduce latency due to context switching. The choice depends on the expected contention and critical section duration.

Can you give an example of when to use each?

Sure! Use a mutex for protecting access to a shared resource like a file or database where contention is high. Use a spinlock for lightweight operations, like incrementing a counter, where the lock is held for a very short time.