[zeromq-dev] Multithreaded ZeroMQ servers

[Pieter Hintjens]

Tom, what language are you working in?

On Mon, Jan 4, 2016 at 12:48 PM, Tom Quarendon
<tom.quarendon at teamwpc.co.uk> wrote:
> I’m confused about writing multithreaded servers with ZeroMQ.
>
> I have read the ZeroMQ guide and there’s a section “Multithreading with
> ZeroMQ” that has a description of how to write a multithreaded Hello World
> server.
>
>
>
> However there appears to be an assumption that the “work” of each request
> takes essentially the same amount of time. That is, the requests are dealt
> out to the workers with a dealer socket, and so the requests are just dealt
> out round robin aren’t they? So if one request takes a long time, you could
> get into the situation that it ends up with lots of requests queued up
> behind it for that worker, and all the other workers are idle. That doesn’t
> seem right to me. But I may be misunderstanding how it works.
>
>
>
> In my mind what you want to be able to do is somehow have all of the threads
> read from the same socket, or bind to the same external endpoint, so that
> the each time a worker does a recv it gets the next message that is in the
> input queue. Either that or you would appear to need each worker to
> disconnect from the inproc socket each time it has received a request to
> process so that it doesn’t get dealt any more, and then reconnect when it
> has finished, but that feels like it might be undesirably inefficient.
> Either that or I have to have a big lock and memory fence around the input
> socket and just have each thread block waiting for the mutex and then
> reading the next message.
>
>
>
> What I seem to want to end up doing is writing my own simple thread safe
> in-process queue that I can just put the requests on to and have all of the
> worker threads read from. However I’d like to use ZeroMQ if I can, I just
> can’t work out how to.
>
>
>
> What am I missing?
>
> Thanks.
>
>
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