[zeromq-dev] PUB/SUB question with IPC

[Pieter Hintjens]

The queue will fill up in the background.

On Wed, Jul 2, 2014 at 9:33 PM, Martin Townsend
<martin.townsend at xsilon.com> wrote:
> Hi Pieter,
>
> Thanks for the swift reply.  I'll give it a go.  Another quick question,
> the process could decide to do something else for minutes maybe even
> hours, would this upset the subscriber or even the publisher or would it
> just fill up it's receive queue?  I just want to know whether it would
> be better to implement a thread to just process the measurements or my
> preference would be to just set the subscriber queue to something like 4
> and then when the process needs to just empty the queue like you
> suggested and keep the most recent result.
>
> Best Regards,
> Martin.
>
> On 02/07/14 17:16, Pieter Hintjens wrote:
>> Simply empty the receive queues every time you read (do a non blocking
>> recv until there's no message), and keep the message that's most
>> useful to you (e.g. the latest one).
>>
>> On Wed, Jul 2, 2014 at 6:11 PM, Martin Townsend
>> <martin.townsend at xsilon.com> wrote:
>>> Hi,
>>>
>>> I want to use the pub/sub pattern for interprocess communication.
>>> Basically I have one application reading measurements and then posts it
>>> to a number of other processes at a fixed rate of every 500 milliseconds.
>>>
>>> One of the subscribing processes is only interested in reading every 2
>>> seconds.  As it queues you get a time lag.  I tried setting the
>>> ZMQ_RCVHWM socket option to 1 to just drop old messages but this doesn't
>>> work.  I suppose I could just create the socket, read the current
>>> message and tear it down but I was wondering if there is a better way or
>>> should I just be using some other IPC like shared memory?
>>>
>>> Best Regards,
>>> Martin.
>>>
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