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From Fraser Adams <fraser.ad...@blueyonder.co.uk>
Subject Re: message duplicates on federated routes
Date Wed, 30 May 2012 17:32:36 GMT
Hi all,
I think we've got to the bottom of this now, the good new is that it 
looks like it's not a qpid issue per se.
We've got a pretty big federated network and we've recently looked into 
partitioning it up better to make management and administration easier 
unfortunately..... during that exercise, and despite having quite a 
detailed transition plan, it looks like a number of the original queue 
routes were left in place instead of being cleaned up when the new paths 
were established.

If I didn't laugh I'd cry :-(

I'd be interested in hearing of how others manage large deployments, the 
tools are good for what they are and QMF gives a lot of good stats, but 
visualising large networks is still pretty hard. I really must crack on 
and get my QMF2 web UI finished, it's my spare time project but it'd 
probably have saved us a load of grief had I actually had it in a state 
I was happy to release :-(


On 29/05/12 23:17, Fraser Adams wrote:
> Hi all,
> we appear to be seeing some fairly large numbers of message 
> duplicates, we've had a few other issues that have caused us to be 
> more observant of what's passing through the system so we're not sure 
> if this is recent of we've simply not noticed before.
>
> We've got quite a heavily federated system with producers delivering 
> to multiple brokers (generally three) providing increasing levels of 
> consolidation.
>
> when we see dupes we've seen two three or four instances of an item 
> but no more and when they occur they appear to happen pretty much 
> immediately after each other a few tens of milliseconds apart.
>
> The routes are "push" queue routes (using qpid-route -s) and 
> delivering to headers exchanges. There's nothing fancy about the 
> route, so they are using normal unreliable links as per the default on 
> federated routes.
>
> can anyone shed any light on this sort of behaviour? Any thoughts on 
> what might be causing it and how to minimise the issue.
>
> BTW we've not proven that it is definitely any issue with qpid or the 
> routes so we're investigating message counts and sampling messages at 
> each hop, but we want to cover off all angles so any thoughts on 
> scenarios that may cause significant dupes would be really useful.
>
> MTIA,
> Frase


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