The author has a point, but the global ordering of an MPMC queue is not entirely pointless. Assuming the queue marks the messages with the order, the ordering m

The author has a point, but the global ordering of an MPMC queue is not entirely pointless. Assuming the queue marks the messages with the order, the ordering might be used at a later stage in the pipeline to reorder the processed messages and recover the total order. Also there are implications for fairness. A queue implemented as a stack might means that messages pushed during a spike might never be processed or experience very high latency. Finally it is actually possible to implement a decent lock free MPSC queue in top of a node-based stack: the consumer would pop all elements on one operation, then reverse the list. This N cost is amortized over N pops so it is actually not bad.