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From Otis Gospodnetic <otis.gospodne...@gmail.com>
Subject Re: New Producer - ONLY sync mode?
Date Mon, 02 Feb 2015 21:27:10 GMT
Hi,

Nope, unfortunately it can't do that.  X is a remote app, doesn't listen to
anything external, calls Y via HTTPS.  So X has to decide what to do with
its data based on Y's synchronous response.  It has to block until Y
responds.  And it wouldn't be pretty, I think, because nobody wants to run
apps that talk to remove servers and hang on to connections more than they
have to.  But perhaps that is the only way?  Or maybe the answer to "I'm
guessing the delay would be more or less the same as if the Producer was
using SYNC mode?" is YES, in which case the connection from X to Y would be
open for just as long as with a SYNC producer running in Y?

Thanks,
Otis
--
Monitoring * Alerting * Anomaly Detection * Centralized Log Management
Solr & Elasticsearch Support * http://sematext.com/


On Mon, Feb 2, 2015 at 4:03 PM, Gwen Shapira <gshapira@cloudera.com> wrote:

> Can Y have a callback that will handle the notification to X?
> In this case, perhaps Y can be async and X can buffer the data until
> the callback triggers and says "all good" (or resend if the callback
> indicates an error)
>
> On Mon, Feb 2, 2015 at 12:56 PM, Otis Gospodnetic
> <otis.gospodnetic@gmail.com> wrote:
> > Hi,
> >
> > Thanks for the info.  Here's the use case.  We have something up stream
> > sending data, say a log shipper called X.  It sends it to some remote
> > component Y.  Y is the Kafka Producer and it puts data into Kafka.  But Y
> > needs to send a reply to X and tell it whether it successfully put all
> its
> > data into Kafka.  If it did not, Y wants to tell X to buffer data locally
> > and resend it later.
> >
> > If producer is ONLY async, Y can't easily do that.  Or maybe Y would just
> > need to wait for the Future to come back and only then send the response
> > back to X?  If so, I'm guessing the delay would be more or less the same
> as
> > if the Producer was using SYNC mode?
> >
> > Thanks,
> > Otis
> > --
> > Monitoring * Alerting * Anomaly Detection * Centralized Log Management
> > Solr & Elasticsearch Support * http://sematext.com/
> >
> >
> > On Mon, Feb 2, 2015 at 3:13 PM, Jay Kreps <jay.kreps@gmail.com> wrote:
> >
> >> Yeah as Gwen says there is no sync/async mode anymore. There is a new
> >> configuration which does a lot of what async did in terms of allowing
> >> batching:
> >>
> >> batch.size - This is the target amount of data per partition the server
> >> will attempt to batch together.
> >> linger.ms - This is the time the producer will wait for more data to be
> >> sent to better batch up writes. The default is 0 (send immediately). So
> if
> >> you set this to 50 ms the client will send immediately if it has already
> >> filled up its batch, otherwise it will wait to accumulate the number of
> >> bytes given by batch.size.
> >>
> >> To send asynchronously you do
> >>    producer.send(record)
> >> whereas to block on a response you do
> >>    producer.send(record).get();
> >> which will wait for acknowledgement from the server.
> >>
> >> One advantage of this model is that the client will do it's best to
> batch
> >> under the covers even if linger.ms=0. It will do this by batching any
> data
> >> that arrives while another send is in progress into a single
> >> request--giving a kind of "group commit" effect.
> >>
> >> The hope is that this will be both simpler to understand (a single api
> that
> >> always works the same) and more powerful (you always get a response with
> >> error and offset information whether or not you choose to use it).
> >>
> >> -Jay
> >>
> >>
> >> On Mon, Feb 2, 2015 at 11:15 AM, Gwen Shapira <gshapira@cloudera.com>
> >> wrote:
> >>
> >> > If you want to emulate the old sync producer behavior, you need to set
> >> > the batch size to 1  (in producer config) and wait on the future you
> >> > get from Send (i.e. future.get)
> >> >
> >> > I can't think of good reasons to do so, though.
> >> >
> >> > Gwen
> >> >
> >> >
> >> > On Mon, Feb 2, 2015 at 11:08 AM, Otis Gospodnetic
> >> > <otis.gospodnetic@gmail.com> wrote:
> >> > > Hi,
> >> > >
> >> > > Is the plan for New Producer to have ONLY async mode?  I'm asking
> >> because
> >> > > of this info from the Wiki:
> >> > >
> >> > >
> >> > >    - The producer will always attempt to batch data and will always
> >> > >    immediately return a SendResponse which acts as a Future to allow
> >> the
> >> > >    client to await the completion of the request.
> >> > >
> >> > >
> >> > > The word "always" makes me think there will be no sync mode.
> >> > >
> >> > > Thanks,
> >> > > Otis
> >> > > --
> >> > > Monitoring * Alerting * Anomaly Detection * Centralized Log
> Management
> >> > > Solr & Elasticsearch Support * http://sematext.com/
> >> >
> >>
>

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