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From Adam Rosien <a...@rosien.net>
Subject Re: high connection-churn solutions
Date Tue, 12 Jun 2012 14:37:24 GMT
That's exactly what we've proposed :)

On Tue, Jun 12, 2012 at 12:36 AM, Mark Gius <mgius7096@gmail.com> wrote:

> Assuming you can't modify the code to keep sessions around longer and your
> queries to zookeeper aren't too varied you could have a REST endpoint web
> service type somewhere that creates a single session and keeps it alive
> indefinitely.  Your existing suite of clients don't have to change their
> behavior and you can avoid the overhead of creating and destroying sessions
> at the same time.
>
> Mark
>
> On Mon, Jun 11, 2012 at 11:09 PM, Patrick Hunt <phunt@apache.org> wrote:
>
> > On Sun, Jun 10, 2012 at 2:42 PM, Adam Rosien <adam@rosien.net> 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
> >
>

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