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

[Matthew Woehlke]

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