This was sent to me privately but should have been sent to the mailing list.
cr Begin forwarded message: > From: Emmanuel TAUREL <[email protected]> > Date: November 29, 2011 6:20:50 AM CST > To: Chuck Remes <[email protected]> > Subject: Re: [zeromq-dev] Some clarifications about HWM for pub/sub > Reply-To: [email protected] > > On 28/11/2011 18:23, Chuck Remes wrote: >> On Nov 28, 2011, at 10:55 AM, Emmanuel TAUREL wrote: >> >>> Hi Chuck, >>> >>> On 28/11/2011 17:26, Chuck Remes wrote: >>>> On Nov 28, 2011, at 10:19 AM, Emmanuel TAUREL wrote: >>>> >>>>> Hello all, >>>>> >>>>> I am using ZMQ 3.0.x on linux boxes with the PUB/SUB pattern. >>>>> I have one publisher and two subscribers. I have a HWM set on the >>>>> publisher to 50 and no HWM on the subscribers. >>>>> When the HWM limit is reached on the publisher, following messages are >>>>> dropped on the publisher side >>>>> and both subscribers do not receive them. >>>>> >>>>> "man zmq_setsockopt" tell me this for the ZMQ_SNDHWM option: >>>>> >>>>> ------------------- >>>>> >>>>> The high water mark is a hard limit >>>>> on the maximum number of outstanding messages 0MQ shall queue in memory >>>>> for any single peer that the specified socket is communicating with. >>>> The part that says "for any single peer" means that each peer has its own >>>> SNDHWM enforcement. >>>> >>>>> ------------------- >>>>> >>>>> Do I have to understand that all peers are affected when the pub HWM is >>>>> reached? >>>> No. Only the peer that has reached the limit is affected. Other peers that >>>> have not reached the limit should not see any message drops. >>> But this is not what I see on wireshark and on my terminal windows! >>> When the HWM is reached, messages are dropped for all peers (at least >>> for the 2 I have in my tests). >>> I don't see them on the wire on both connections (connection1 with port1 >>> for sub1 and connection2 with port2 for sub2) and my two >>> applications using the subscribers complain. >>> >>> Therefore, I am a bit confused and I don't really know what should be >>> the wanted behavior. >> You are going to have to share your code with us. Put it up at pastie.org or >> gist.github.com along with directions on how to run it. >> >> cr >> > > The code is now at https://gist.github.com/b7e0168b0c40bef57378 > There is one file for the publisher and another one for the subscriber (C++). > The third file contains only comments. > Both subscribers do not receive messages when the publisher high water mark > is reached. This is something I understand because if the > messages are dropped (due to HWM) and not inserted into the pub queue, how > could they be transmitted to any subscribers? > > But this is only a guess and I would like to have confirmation from experts. > If this is confirmed, I think the man page sentence (man zmq_setsockopt) > reported in the mail at the origin of this thread is not really clear. > But English is not my mother tongue and the problem is may be simply due to > my English understanding > > Regards > > Emmanuel >
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