As I have been writing some multi-threaded code for fun, I came up with the following situation:
a thread claims a single resource unit from a memory pool, it processes it and sends a pointer to this data to another thread for further operation using a circular buffer (1R / 1W case).
The latter must inform the former thread whenever it is done with the data he received, so that the memory can be recycled.
I wonder whether it is better – performance-wise – to implement this “Freelist” as another circular buffer – holding the addresses of free resources – or choose the lock-free stack way (implementing DCAS on x86-64).
Generally speaking, what could be the pros and the cons of the two different approaches ?
Just in case, there is a difference between lock-free and wait-free. The former means there is no locking but the thread can still busy-spin not making any progress. The latter means that the thread always makes progress with no locking or busy-spinning.
With one reader and one writer lock-free and wait-free FIFO circular buffer is trivial to implement.
I hear that LIFO stack can also be made wait-free, but not so sure about FIFO list. And it sound like you need a queue here rather then a stack.