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From Stephan Ewen <se...@apache.org>
Subject Re: Flink on EMR Question
Date Tue, 05 Jan 2016 14:59:12 GMT
Hi!

Concerning (1) We have seen that a few times. The JVMs / Threads do
sometimes not properly exit in a graceful way, and YARN is not always able
to kill the process (YARN bug). I am currently working on a refactoring of
the YARN resource manager (to allow to easy addition of other frameworks)
and have addressed this as part of that. Will be in the master in a bit.

Concerning (2) Do you know which component in Flink uses the HTTP client?

Greetings,
Stephan


On Tue, Jan 5, 2016 at 2:49 PM, Maximilian Bode <maximilian.bode@tngtech.com
> wrote:

> Hi everyone,
>
> Regarding Q1, I believe I have witnessed a comparable phenomenon in a
> (3-node, non-EMR) YARN cluster. After shutting down the yarn session via
> `stop`, one container seems to linger around. `yarn application -list` is
> empty, whereas `bin/yarn-session.sh -q` lists the left-over container.
> Also, there is still one application shown as ‚running‘ in Ambari’s YARN
> pane under current applications. Then, after some time (order of a few
> minutes) it disappears and the resources are available again.
>
> I have not tested this behavior extensibly so far. Noticeably, I was not
> able to reproduce it by just starting a session and then ending it again
> right away without looking at the JobManager web interface. Maybe this
> produces some kind of lag as far as YARN containers are concerned?
>
> Cheers,
> Max
>
> > Am 04.01.2016 um 12:52 schrieb Chiwan Park <chiwanpark@apache.org>:
> >
> > Hi All,
> >
> > I have some problems using Flink on Amazon EMR cluster.
> >
> > Q1. Sometimes, jobmanager container still exists after destroying yarn
> session by pressing Ctrl+C. In that case, Flink YARN app seems exited
> correctly in YARN RM dashboard. But there is a running container in the
> dashboard. From logs of the container, I realize that the container is
> jobmanager.
> >
> > I cannot kill the container because there is no permission to restart
> YARN RM in Amazon EMR. In my small Hadoop Cluster (w/3 nodes), the problem
> doesn’t appear.
> >
> > Q2. I tried to use S3 file system in Flink on EMR. But I can’t use it
> because of version conflict of Apache Httpclient. In default,
> implementation of S3 file system in EMR is
> `com.amazon.ws.emr.hadoop.fs.s3n.S3NativeFileSystem` which is linked with
> other version of Apache Httpclient.
> >
> > As I wrote above, I cannot restart Hadoop cluster after modifying
> conf-site.xml because of lack of permission. How can I solve this problem?
> >
> > Regards,
> > Chiwan Park
> >
> >
>
>

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