[zeromq-dev] Assertion failed

Martin Sustrik sustrik at 250bpm.com
Thu Apr 8 15:00:04 CEST 2010

Hi Emmanuel,

> As one of my subscriber has received all my messages, I think the 
> network delivered all the messages. I have attached to this email, the 
> dump of Wireshark of the network transfer. What surprised me in this 
> graph, is the "holes" we can see in the network usage. If I follow the 
> sequence number in the epgm packets stream,
> I notice "holes" in packet sequence number at the moment where according 
> to the graph there is no traffic.
> Everything looks like some network packet has not been transferred to 
> wireshark. However, these packets has been transmitted on the network 
> otherwise none of my subscribers will have reported a correct transmission.
> If some packets have not been transmitted to wireshark, I guess the same 
> things happened for my 4 subscribers which has lost messages.

I have no idea how dispatching the packets to individual applications is 
implemented. Steven may have a better understanding of the problem (I'm 
cc'ing OpenPGM mailing list).

> In one of your previous e-mail, you talked about
> kernel implementation of multicast packet dispatching.
> My kernel is linux 2.6.28-18. Do you think that this multicast packet 
> dispatching done by the kernel could be the reason of the behavior I am 
> observing?
> If yes, I guess the solution is to decrease the RATE until the kernel is 
> able to reliably dispatch all the packets received to all the involved 
> subscribers.

I don't think the rate is problem. By default it's 100kb/sec which is 
extremely low and the system should experience any problems with it.


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