spin

the longest a worker that ran out of messages spins before it parks, at most MAX_SPIN; the default, Duration.ZERO, parks at once (no spin). Worth setting only for in-memory, high-rate dispatch whose messages keep arriving within microseconds of each other; with a real store the gain is within noise. A worker spins only when its last wait was shorter than this; after a longer wait it parks at once. A spinning worker takes the next message without the wake-up a park costs (an OS call by the sender and the scheduling delay of the woken thread). CPU cost: while messages keep arriving at intervals shorter than the spin, a worker can stay busy on one core the whole time; after each short interval, the next wait can cost up to the spin in CPU even when no message follows. The worst case is workers cores. In a container with a CPU quota (cgroup limit), set it to Duration.ZERO.