[zeromq-dev] HWM default

Martin Sustrik sustrik at 250bpm.com
Mon May 9 08:26:17 CEST 2011

Hi Blair,

> On 9 May 2011 15:40, Martin Sustrik<sustrik at 250bpm.com>  wrote:
>> It should be acknowledged though that OOMs are easier to debug than
>> deadlocks. However, debugging is not exactly newbie activity. It's
>> likely to be performed by more experienced users which should be aware
>> of an option of setting HWM to infinity to induce OOMs.
>> Thoughts?
> An experienced programmer coming to 0MQ is likely to attempt their own
> debugging, so what do you mean by newbie?

A new person trying the simplest possible use case. Publish messages in 
a loop: Oh my, it's out of memory! Let's switch to some more reasonable 
messaging system!

> +1 for Pieter's context config option. I think I agree having a
> default HWM would be good, however, only if HWM events are easily
> exposed.

The context options are a different issue. They are completely 
orthogonal to what the default for HWM should be. Let's discuss them in 
a separate thread.

> As an aside, any idea of the 0MQ behaviour under flooding with no HWM
> but sane kernel virtual memory settings (i.e.,
> /proc/sys/vm/overcommit_memory=2)...?

Sorry, no experience, however, when publisher is publishing faster than 
receiver is receiving the size of the queue grows without limit. In such 
case no tuning is going to help.


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