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From Otis Gospodnetic <otis.gospodne...@gmail.com>
Subject Re: New Producer - ONLY sync mode?
Date Mon, 02 Feb 2015 20:56:47 GMT
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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