On Wed, Feb 5, 2014 at 6:14 AM, Ben Hood <0x6e6...@gmail.com> wrote: > What is the general approach to this from a server perspective? Is > there any flow control that the server can apply to back pressure onto > the sending driver?
No. In theory the client could look at dynamic snitch scores, I suppose, if the dynamic snitch worked right... For most clients, my belief is the only backpressure is that, once a node is severely overloaded, it will stop attempting to write hints and return an OverloadedException. But this is only on the hint write path, not the normal write path. > If not, how do other driver implementors view this situation? Do you > try to maintain some kind of flow control at the driver level so that > you can push back onto the app, or you just let the effects of IO > saturation just bubble up to the app? > I think most deploys of Cassandra deal with this reality by carefully managing available capacity so that they don't risk getting in this situation. I understand that is not a technical solution appropriate to your question's scope, but I do believe it describes the status quo. =Rob
