Queues 101

A queue is a buffer that hands work from a producer to a consumer.

Idea	Meaning
SPSC	One producer, one consumer
MPSC / MPMC	Several producers and/or consumers
Bounded	Put waits (or fails) when full — backpressure
Unbounded	Put always succeeds until memory is gone
Blocking	Get waits for an item
Async	Same contract, but the waiter yields the event loop
Locked	A mutex protects a simple structure
Lock-free / ring	Progress without a mutex on the happy path

This suite measures in-process queues. A broker on the network is a different experiment.

This suite’s comparison boundary is communication category (thread vs async vs process vs shared memory vs durable), not “every library on one chart.” See queue categories and comparison rules.