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From Márton Balassi <balassi.mar...@gmail.com>
Subject Re: Flink on YARN - how to resize a running cluster?
Date Thu, 30 Jun 2016 10:47:53 GMT
Hi Josh,

Yes, currently that is a reasonable workaround.



On Thu, Jun 30, 2016 at 12:38 PM, Josh <jofo90@gmail.com> wrote:

> Hi Till,
> Thanks, that's very helpful!
> So I guess in that case, since it isn't possible to increase the job
> parallelism later, it might be sensible to use say 10x the parallelism that
> I need right now (even if only running on a couple of task managers) - so
> that it's possible to scale the job in the future if I need to?
> Josh
> On Thu, Jun 30, 2016 at 11:17 AM, Till Rohrmann <trohrmann@apache.org>
> wrote:
>> Hi Josh,
>> at the moment it is not possible to dynamically increase the parallelism
>> of your job. The same holds true for a restarting a job from a savepoint.
>> But we're currently working on exactly this. So in order to change the
>> parallelism of your job, you would have to restart the job from scratch.
>> Adding task managers dynamically to your running Flink cluster, is
>> possible if you allocate new YARN containers and then start a TaskManager
>> process manually with the current job manager address and port. You can
>> either find the address and port out using the web dashboard under job
>> manager configuration or you look up the .yarn-properties file which is
>> stored in your temp directory on your machine. This file also contains the
>> job manager address. But the easier way would be to stop your yarn session
>> and then restart it with an increased number of containers. Because then,
>> you wouldn't have to ship the lib directory, which might contain user code
>> classes, manually.
>> Cheers,
>> Till
>> On Wed, Jun 29, 2016 at 10:13 PM, Josh <jofo90@gmail.com> wrote:
>>> I'm running a Flink cluster as a YARN application, started by:
>>> ./bin/yarn-session.sh -n 4 -jm 2048 -tm 4096 -d
>>> There are 2 worker nodes, so each are allocated 2 task managers. There
>>> is a stateful Flink job running on the cluster with a parallelism of 2.
>>> If I now want to increase the number of worker nodes to 3, and add 2
>>> extra task managers, and then increase the job parallelism, how should I do
>>> this?
>>> I'm using EMR, so adding an extra worker node and making it available to
>>> YARN is easy to do via the AWS console. But I haven't been able to find any
>>> information in Flink docs about how to resize a running Flink cluster on
>>> YARN. Is it possible to resize it while the YARN application is running, or
>>> do I need to stop the YARN application and redeploy the cluster? Also do I
>>> need to redeploy my Flink job from a savepoint to increase its parallelism,
>>> or do I do this while the job is running?
>>> I tried redeploying the cluster having added a third worker node, via:
>>> > yarn application -kill myflinkcluster
>>> > ./bin/yarn-session.sh -n 6 -jm 2048 -tm 4096 -d
>>> (note increasing the number of task managers from 4 to 6)
>>> Surprisingly, this redeployed a Flink cluster with 4 task mangers (not
>>> 6!) and restored my job from the last checkpoint.
>>> Can anyone point me in the right direction?
>>> Thanks,
>>> Josh

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