For context, the traditional wait-free queues are only wait-free for one side, writing or reading. The other side has to spin in an atomic fetch loop, waiting f

For context, the traditional wait-free queues are only wait-free for one side, writing or reading. The other side has to spin in an atomic fetch loop, waiting for the wait-free multi-step operation to complete. The double wait-free queue from the paper is using a technicality to achieve its status. The spinning operation is replaced with a loop over all the threads doing opposite (multi-step) operations, finishing them for threads that may be blocked in the middle of the steps. It's not that it doesn't spin, but the spinning is bounded by the number of threads. Edit: Actually, spinning is bounded by O(#threads^4) according to the paper.