On Sun, Jun 10, 2012 at 2:42 PM, Adam Rosien <[email protected]> wrote: > Various people in my company are using zk as a pure high-throughput > read-only cache (only get() operations) and I am trying to convince them > this is a bad idea. Specifically: > > * I believe their clients do not manage (or do not manage well) persistent > connections, so there is a high amount of connection/session churn. > * This churn results in increased quorum writes, because creating a session > is a quorum operation. (Is this correct? Looking at snapshot log dumps, it > seems so.)
That's correct. > * Increased quorum writes from read-only operations is bad. Why? Not sure I follow the thinking here. (esp if you fix session handling to be longer lived) > > To avoid this situation, one could: > > 1. Not do this. > 2. Create a read-only connection/session that doesn't involve the quorum or > writing, somehow. I believe Facebook has been working on something like this - a "server local session" for things like r/o clients. > 3. Something else. > > How could one do #2? Do observers allow #2? Any other suggestions? > Perhaps someone from FB might be able to comment on their progress... Patrick
