12.BlockingQueue

A fixed-capacity array-backed blocking queue with explicit backpressure, FIFO element order, and optional fairness.

Producer-consumer queues with bounded capacity, blocking/timed operations, backpressure, and the semantics of major Java BlockingQueue implementations.

A linked-node blocking queue with optional capacity, separate producer/consumer coordination, and the risk of its very large default bound.

An unbounded priority heap for concurrent producers/consumers, with ordering, capacity, and starvation caveats.

A zero-capacity rendezvous queue that directly hands an element from producer to consumer, with fair/nonfair transfer modes and thread-pool implications.