Re: How random is Metron's Doppler selection?
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John Tuley <jtuley@...>
Mike,
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I don't want to speak to the possibility, but I can explain why we decided against app affinity. Basically, it comes down to sharding over a dynamic pool. As Doppler instances come and go, Metron would need to re-balance its affinity calculations. This becomes troublesome if you assume that a single Doppler is responsible for each app (or app-instance), including the recent history: does the old home of an app need to transfer history to the new home? Or maybe a new server just picks up new apps, and all the old mappings stay the same? We did some research into algorithms for this sort of consistent hashing/sharding and determined that it would be difficult to implement in the presence of distributed servers *and* distributed clients. Given that your goals don't include history, the problem becomes easier for sure. But I'd (personally – not speaking for product leadership) be wary of accepting a PR that only solved forward-rebalancing without addressing the problem of historical data. – John Tuley
On Thu, Jun 11, 2015 at 4:55 PM, Mike Heath <elcapo(a)gmail.com> wrote:
Actually, this might explain why some of our customers are so frustrated
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