[zeromq-dev] "first time" missing messages?

[Pieter Hintjens]

Connections are asynchronous and take about 100ms (depending on the
network) so anything sent during that time, to a sub socket, will be
dropped. You would usually use long-lasting connections, or use a
different socket pair (push/pull, for instance). pub-sub by design
does not queue up messages it cannot deliver.

On Tue, Aug 27, 2013 at 7:06 PM, Matthew Woehlke
<matthew.woehlke at kitware.com> wrote:
> We have a client-server application that runs queries against a database
> using 0MQ as a transport.
>
> The client is transport-agnostic; there is only a plugin that knows
> about 0MQ. For each query, we create a new query session, which creates
> new 0MQ contexts/sockets/etc. The server I believe has persistent 0MQ
> sockets.
>
> The client runs a query by sending a message over socket A to the
> server. The server then sends back results, which may involve tens of
> thousands of messages at a few hundred per second.
>
> On Linux this seems to be working okay. However on Windows, the *first*
> query seems to be losing messages. This in and of itself is perhaps not
> shocking, but what is really puzzling us is that if the client then runs
> the same query a second time, no loss occurs.
>
> Does anyone know why this might be happening? Is there some sort of
> network tuning possibly happening that would be preventing loss the
> second time? Is there a recommended way to adjust things to avoid the
> initial loss?
>
> (Note: because the client connect()'s the SUB socket on which the
> responses are received before issuing the query to the server, I don't
> believe we are losing initial messages due to connect lag. Also, the
> first and last messages are special/marked and AFAIK we are getting both.)
>
> --
> Matthew
>
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