[zeromq-dev] Problem with lost clients

[Michel Pelletier]

Ah sorry you're right I didn't correctly understand your question.

If your client disconnects its socket the router should free the
resources.  If you set ZMQ_ROUTER_MANDATORY an error will be returned if
the peer no longer exists.


-Michel

On Thu, Apr 23, 2015 at 8:03 AM, Diego Fons <diego.fons at intraway.com> wrote:

> Hi Michel,
>
> I'm aware of that, but I still don't know how that can help me with the
> problem (may be I was not clear enough).
>
> Using credit-based flow:
> - The client connects with identity A.
> - The client asks for chunks 0 to 9.
> - The client dies (it means the socket will be re-created and
> re-connected).
> - The server sends all the 10 chunks.
> - The server detects the client is dead.
> - The client reconnects with identity B (we can not reuse identities).
> - The client asks for chunks 0 to 9 again.
> - etc...
>
> I know that if the server tries to send a chunk to client with identity A
> after the crash, the chunks are dropped. But, what happen with the 10
> chunks already sent to client with identity A?
>
> Am I misunderstanding the guide? Is there anything implicit in the ROUTER
> behavior that I missed? Should I assume that a message being dropped by the
> ROUTER implies that all queued messages were already dropped?
>
> Regards.
>
> On Wed, Apr 22, 2015 at 1:10 PM, Michel Pelletier <
> pelletier.michel at gmail.com> wrote:
>
>> There's good information in the guide about solving these kinds of
>> problems.  In particular:
>>
>> http://zguide.zeromq.org/hx:chapter7#State-Machines
>>
>> But read the whole chapter, it will explain credit based flow control and
>> heartbeating as well.
>>
>> -Michel
>>
>> On Wed, Apr 22, 2015 at 8:01 AM, Diego Fons <diego.fons at intraway.com>
>> wrote:
>>
>>> Hi,
>>>
>>> I'm building an application that consists of several clients using
>>> DEALER sockets which connects to one server using ROUTER socket.
>>>
>>> The communication is quite simple:
>>>   - Client sends a START message to server.
>>>   - Server sends back an OK message to client.
>>>   - Server starts sending a stream of data to server (until client asks
>>> to stop it).
>>>   - Client sends a STOP message to server.
>>>   - Server sends back an OK message to client.
>>>
>>> The problem:
>>>   - Client sends a START message to server.
>>>   - Client crashes.
>>>   - Server sends back an OK message to client.
>>>   - Server starts sending a stream of data to server (until client asks
>>> to stop it).
>>>
>>> The client never sends the STOP an the server will continue sending
>>> messages until the HWM is reached. The problem is not how to know when a
>>> client dies, I'm able to know it. The problem is how to release all the
>>> resources used by ZMQ in order to handle the dead client, I mean, all those
>>> enqueued messages.
>>>
>>> The only solution I see untill now, is to close the ROUTER and re-bind
>>> it, but I face the problem that another client (several ones) could be
>>> perfectly working ans if I close the ROUTER, may be some data could be lost.
>>>
>>> So, I have two options:
>>>   1) Wait untill no clients are active and close the ROUTER.
>>>   2) Try to change the pattern (possibly use a pattern with two
>>> communication channels).
>>>
>>> Any comments about his?
>>>
>>> Regards.
>>>
>>> --
>>> Diego Andrés Fons
>>> Intraway Corp.
>>> Solution Developer
>>> AR Office: +54 (11) 6040 4000
>>> US Office: +1 (516) 620 3890
>>> Email: diego.fons at intraway.com
>>>
>>> Visit our website at http://www.intraway.com
>>> Proud to be an ISO 9001:2008 certified company
>>>
>>> _______________________________________________
>>> zeromq-dev mailing list
>>> zeromq-dev at lists.zeromq.org
>>> http://lists.zeromq.org/mailman/listinfo/zeromq-dev
>>>
>>>
>>
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>>
>>
>
>
> --
> Diego Andrés Fons
> Intraway Corp.
> Solution Developer
> AR Office: +54 (11) 6040 4000
> US Office: +1 (516) 620 3890
> Email: diego.fons at intraway.com
>
> Visit our website at http://www.intraway.com
> Proud to be an ISO 9001:2008 certified company
>
> _______________________________________________
> zeromq-dev mailing list
> zeromq-dev at lists.zeromq.org
> http://lists.zeromq.org/mailman/listinfo/zeromq-dev
>
>
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