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From "Jain, Ankit" <ankit.j...@here.com>
Subject High Availability on Yarn
Date Mon, 01 May 2017 16:59:59 GMT
Hi fellow users,
We are trying to straighten out high availability story for flink.

Our setup includes a long running EMR cluster, job submission is a two-step process – 1)
Flink cluster is first created using flink yarn client on the EMR cluster already running
2) Flink job is submitted.

I also saw references that with 1.2, these two steps have been combined into 1 – is that
change in FlinkYarnSessionCli.java? Can somebody point to documentation please?

W/o worrying about Yarn RM (not Flink Yarn RM that seems to be newly introduced) failure for
now, I want to understand first how task manager & job manager failures are handled.

My questions-

1)       https://cwiki.apache.org/confluence/pages/viewpage.action?pageId=65147077 suggests
a new RM has been added and now there is one JobManager for each job. Since Yarn RM will now
talk to Flink RM( instead of JobManager previously), will Yarn automatically restart failing
Flink RM?

2)       Is there any documentation on behavior of new Flink RM that will come up? How will
previously running JobManagers & TaskManagers find out about new RM?

3)       https://ci.apache.org/projects/flink/flink-docs-release-1.3/setup/jobmanager_high_availability.html#configuration
requires configuring Zookeeper even for Yarn – Is this needed for handling Task Manager
failures or JM or both? Will Yarn not take care of JM failures?

It may sound like I am little confused between role of Yarn and Flink components– who has
the most burden of HA? Documentation in current state is lacking clarity – I know it is
still evolving.

Please let me know if somebody can help clear the confusion.


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