[zeromq-dev] ZMQ_HWM handling: impossible to disable queuing

Martin Sustrik sustrik at 250bpm.com
Mon Nov 22 15:35:48 CET 2010


> Current semantics of ZMQ_HWM (0 = no limit) mean that it's impossible
> to disable message queueing, which could be very useful in some
> applications. It would be great if default value of ZMQ_HWM has been
> changed to UINT64_MAX and ZMQ_HWM of 0 disabled queuing at all. Is
> there any downside to it that I don't see (other than API semantics
> change)?

I would say, the problem is that you don't achieve anything useful by 
disabling the queueing at 0MQ level. The messages can still be queued in 
TCP buffers, in NIC buffers etc. In short, network itself behaves as a 
queue and tweaking thin layer on top of network stack (0MQ) doesn't 
change that in any way.


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