[zeromq-dev] Understanding ØMQ PubSub Scaling

Martin Sustrik sustrik at 250bpm.com
Tue Jan 11 22:37:40 CET 2011

On 01/11/2011 10:30 PM, dave wrote:

> Back to my original question: It sounds like, with appropriate
> forwarders set up, the machine-to-machine communication won't be much of
> a hurdle. On a local machine, with ipc or inproc setup, can I expect a
> single publisher to be able to quickly publish to 10k subscribers?

It mostly depends on your OS. With high number of subscribers you are 
likely to run into socket limits, swapping the buffers out of memory and 

> Is it
> copying the data round 10k times, or is it doing something sneakier?

It's not copying data, but with small messages it's unlikely to make 
much difference.

> Perhaps I am underestimating it and it could easily handle a billion
> subscribers?

With a single-layer topology you'll run into the limitations of the OS 
on the PUB box. Mutliple level distribution tree should help in such case.


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