[rabbitmq-discuss] MTU

[Gustavo Aquino]

Thanks guys.

On Mon, May 10, 2010 at 6:30 AM, Matthew Sackman <matthew at lshift.net> wrote:

> On Mon, May 10, 2010 at 09:35:24AM +0200, Martin Sustrik wrote:
> > Gustavo,
> >
> > > If RabbitMQ are receiving 20 messages per millisecond from publisher
> and
> > > each message have 213 bytes, what the size of packages over network to
> a
> > > consumer or other broker?
> >
> > 20 msgs/ms = 1 message each 50 us
> >
> > This means (under Linux at least) that each message is sent as a
> > separate packet. Or maybe three packets per message. It depends on
> > whether RabbitMQ sends message using single OS call or whether is sends
> > each frame separately.
>
> We make one call to write the entire message. Whilst this, at least in
> Erlang land, consists of writing an io_list (which is a (potentially
> deep) list of binaries), last I checked, this is very performant as
> Erlang maps this to a writev, thus does not have overheads of copying
> data into one contiguous block before writing.
>
> Matthew
>
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