A million messages per minute ? How's that a problem? Please see http://bravenewgeek.com/dissecting-message-queues/

Almost all of the systems tested hit 17k / s (aside from NSQ) -- on a laptop. NATS (gnatsd) hits 0.2M per second, that's a magnitude above what you need and that's a brokered system, if your task fits with a brokerless one then nanomsg is yet another magnitude. I do not particularly see where the problem really is?

Our messages range from a few KB to a few MB (we store a pointer to S3 for the large ones) but that look pretty interesting.

Thanks