[zeromq-dev] Queueing outgoing messages

Martin Sustrik sustrik at 250bpm.com
Thu Jul 22 11:39:38 CEST 2010


Ilja,

> I am sorry - client blocks on recv.
>> Hello!
>>  
>>  Playing with "A simple client/server application" from Cookbook I've found out client blocks if no server run.
>>  
>>  Knowing from zmq_setsockopt(3), "The default 'ZMQ_HWM' value of zero means "no limit"",
>>  I'd expect different behavior.
>>  
>>  Could someone please explain?

HWM is the limit on pipe to particular peer. So if you have 2 peers and 
HWM is set to 100, there can be 200 messages in-flight.

When you have no peers, there's no pipe to apply HWM on and the 
behaviour is defined by the messaging patters (in short, drop message 
for pub/sub, block for other patterns).

Martin



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