ZeroMQ individual subscriber queues

Question

I have a question about ZeroMQ PUB/SUB. Does the publisher create a separate queue for each individual subscriber or is there one queue for all subscribers (and hence limited by the slowest subscriber)?

Answer 1

Each connected subscriber gets its own queue. When a subscriber is slow, its own queue will fill up and then overflow (high water mark is by default 1,000), and its messages will get dropped. This won't affect other subscribers.