[zeromq-dev] High water mark notification for publisher

[Pieter Hintjens]

On Sat, Sep 22, 2012 at 12:57 AM, Edwin Amsler
<edwinamsler at thinkboxsoftware.com> wrote:

> It was mentioned that under the hood, the PUB-SUB system had individual
> outgoing queues, each with their own water mark counters. What happens
> to a message when all queues are full?

This is such an unlikely case... almost contrived. The real issue with
high-speed pub/sub is a small number of clients disconnecting or
getting swamped by other work, and their queues building up, and
causing memory exhaustion.

The best strategy to keep data flowing but also ensure reliability is
then some kind of out-of-band recovery for clients that need it.
There's some ideas in the Clone pattern in the Guide (request snapshot
at startup, then apply changes as they arrive to the snapshot).

-Pieter