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From Till Rohrmann <trohrm...@apache.org>
Subject Re: Distribution of sinks among the nodes
Date Wed, 03 Feb 2016 16:58:29 GMT
Hi Gwenhäel,

if you set the number of slots for each TaskManager to 4, then all of your
mapper will be evenly spread out. The sources should also be evenly spread
out. However, for the sinks since they depend on all mappers, it will be
most likely random where they are deployed. So you might end up with 4 sink
tasks on one machine.

Cheers,
Till
​

On Wed, Feb 3, 2016 at 4:31 PM, Gwenhael Pasquiers <
gwenhael.pasquiers@ericsson.com> wrote:

> It is one type of mapper with a parallelism of 16
> It's the same for the sinks and sources (parallelism of 4)
>
> The settings are
> Env.setParallelism(4)
> Mapper.setPrallelism(env.getParallelism() * 4)
>
> We mean to have X mapper tasks per source / sink
>
> The mapper is doing some heavy computation and we have only 4 kafka
> partitions. That's why we need more mappers than sources / sinks
>
>
> -----Original Message-----
> From: Aljoscha Krettek [mailto:aljoscha@apache.org]
> Sent: mercredi 3 février 2016 16:26
> To: user@flink.apache.org
> Subject: Re: Distribution of sinks among the nodes
>
> Hi Gwenhäel,
> when you say 16 maps, are we talking about one mapper with parallelism 16
> or 16 unique map operators?
>
> Regards,
> Aljoscha
> > On 03 Feb 2016, at 15:48, Gwenhael Pasquiers <
> gwenhael.pasquiers@ericsson.com> wrote:
> >
> > Hi,
> >
> > We try to deploy an application with the following “architecture” :
> >
> > 4 kafka sources => 16 maps => 4 kafka sinks, on 4 nodes, with 24 slots
> (we disabled operator chaining).
> >
> > So we’d like on each node :
> > 1x source => 4x map => 1x sink
> >
> > That way there are no exchanges between different instances of flink and
> performances would be optimal.
> >
> > But we get (according to the flink GUI and the Host column when looking
> at the details of each task) :
> >
> > Node 1 : 1 source =>  2 map
> > Node 2 : 1 source =>  1 map
> > Node 3 : 1 source =>  1 map
> > Node 4 : 1 source =>  12 maps => 4 sinks
> >
> > (I think no comments are needed J)
> >
> > The the Web UI says that there are 24 slots and they are all used but
> they don’t seem evenly dispatched …
> >
> > How could we make Flink deploy the tasks the way we want ?
> >
> > B.R.
> >
> > Gwen’
>
>

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