Library of lock-free constructs.
From C++ Concurrency in Action - Anthony Williams
Obstruction-Free: If all other threads are paused, then any given thread will complete its operation in a bounded number of steps. Lock-Free: If multiple threads are operating on a data structure, then after a bounded number of steps one of them will complete its operation. Wait-Free: Every thread operating on a data structure will complete its operation in a bounded number of steps, even if other threads are also operating on the data structure.
Lock-Free guarantees that a misbehaving thread cannot block any other thread.