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From Till Rohrmann <trohrm...@apache.org>
Subject Re: YARN High Availability
Date Mon, 23 Nov 2015 13:51:16 GMT
The problem is the execution graph handle which is stored in ZooKeeper. You
can manually remove it via the ZooKeeper shell by simply deleting
everything below your `recovery.zookeeper.path.root` ZNode. But you should
be sure that the cluster has been stopped before.

Do you start the different clusters with different
`recovery.zookeeper.path.root` values? If not, then you should run into
troubles when running multiple clusters at the same time. The reason is
that then all clusters will think that they belong together.

Cheers,
Till

On Mon, Nov 23, 2015 at 2:15 PM, Gwenhael Pasquiers <
gwenhael.pasquiers@ericsson.com> wrote:

> OK, I understand.
>
> Maybe we are not really using flink as you intended. The way we are using
> it, one cluster equals one job. That way we are sure to isolate the
> different jobs as much as possible and in case of crashes / bugs / (etc)
> can completely kill one cluster without interfering with the other jobs.
>
> That future behavior seems good :-)
>
> Instead of the manual flink commands, is there to manually delete those
> old jobs before launching my job ? They probably are somewhere in hdfs,
> aren't they ?
>
> B.R.
>
>
> -----Original Message-----
> From: Ufuk Celebi [mailto:uce@apache.org]
> Sent: lundi 23 novembre 2015 12:12
> To: user@flink.apache.org
> Subject: Re: YARN High Availability
>
> Hey Gwenhaël,
>
> the restarting jobs are most likely old job submissions. They are not
> cleaned up when you shut down the cluster, but only when they finish
> (either regular finish or after cancelling).
>
> The workaround is to use the command line frontend:
>
> bin/flink cancel JOBID
>
> for each RESTARTING job. Sorry about the inconvenience!
>
> We are in an active discussion about addressing this. The future behaviour
> will be that the startup or shutdown of a cluster cleans up everything and
> an option to skip this step.
>
> The reasoning for the initial solution (not removing anything) was to make
> sure that no jobs are deleted by accident. But it looks like this is more
> confusing than helpful.
>
> – Ufuk
>
> > On 23 Nov 2015, at 11:45, Gwenhael Pasquiers <
> gwenhael.pasquiers@ericsson.com> wrote:
> >
> > Hi again !
> >
> > On the same topic I'm still trying to start my streaming job with HA.
> > The HA part seems to be more or less OK (I killed the JobManager and it
> came back), however I have an issue with the TaskManagers.
> > I configured my job to have only one TaskManager and 1 slot that does
> [source=>map=>sink].
> > The issue I'm encountering is that other instances of my job appear and
> are in the RESTARTING status since there is only one task slot.
> >
> > Do you know of this, or have an idea of where to look in order to
> understand what's happening ?
> >
> > B.R.
> >
> > Gwenhaël PASQUIERS
> >
> > -----Original Message-----
> > From: Maximilian Michels [mailto:mxm@apache.org]
> > Sent: jeudi 19 novembre 2015 13:36
> > To: user@flink.apache.org
> > Subject: Re: YARN High Availability
> >
> > The docs have been updated.
> >
> > On Thu, Nov 19, 2015 at 12:36 PM, Ufuk Celebi <uce@apache.org> wrote:
> >> I’ve added a note about this to the docs and asked Max to trigger a new
> build of them.
> >>
> >> Regarding Aljoscha’s idea: I like it. It is essentially a shortcut for
> configuring the root path.
> >>
> >> In any case, it is orthogonal to Till’s proposals. That one we need to
> address as well (see FLINK-2929). The motivation for the current behaviour
> was to be rather defensive when removing state in order to not loose data
> accidentally. But it can be confusing, indeed.
> >>
> >> – Ufuk
> >>
> >>> On 19 Nov 2015, at 12:08, Till Rohrmann <trohrmann@apache.org> wrote:
> >>>
> >>> You mean an additional start-up parameter for the `start-cluster.sh`
> script for the HA case? That could work.
> >>>
> >>> On Thu, Nov 19, 2015 at 11:54 AM, Aljoscha Krettek <
> aljoscha@apache.org> wrote:
> >>> Maybe we could add a user parameter to specify a cluster name that is
> used to make the paths unique.
> >>>
> >>>
> >>> On Thu, Nov 19, 2015, 11:24 Till Rohrmann <trohrmann@apache.org>
> wrote:
> >>> I agree that this would make the configuration easier. However, it
> entails also that the user has to retrieve the randomized path from the
> logs if he wants to restart jobs after the cluster has crashed or
> intentionally restarted. Furthermore, the system won't be able to clean up
> old checkpoint and job handles in case that the cluster stop was
> intentional.
> >>>
> >>> Thus, the question is how do we define the behaviour in order to
> retrieve handles and to clean up old handles so that ZooKeeper won't be
> cluttered with old handles?
> >>>
> >>> There are basically two modes:
> >>>
> >>> 1. Keep state handles when shutting down the cluster. Provide a mean
> to define a fixed path when starting the cluster and also a mean to purge
> old state handles. Furthermore, add a shutdown mode where the handles under
> the current path are directly removed. This mode would guarantee to always
> have the state handles available if not explicitly told differently.
> However, the downside is that ZooKeeper will be cluttered most certainly.
> >>>
> >>> 2. Remove the state handles when shutting down the cluster. Provide a
> shutdown mode where we keep the state handles. This will keep ZooKeeper
> clean but will give you also the possibility to keep a checkpoint around if
> necessary. However, the user is more likely to lose his state when shutting
> down the cluster.
> >>>
> >>> On Thu, Nov 19, 2015 at 10:55 AM, Robert Metzger <rmetzger@apache.org>
> wrote:
> >>> I agree with Aljoscha. Many companies install Flink (and its config)
> in a central directory and users share that installation.
> >>>
> >>> On Thu, Nov 19, 2015 at 10:45 AM, Aljoscha Krettek <
> aljoscha@apache.org> wrote:
> >>> I think we should find a way to randomize the paths where the HA stuff
> stores data. If users don’t realize that they store data in the same paths
> this could lead to problems.
> >>>
> >>>> On 19 Nov 2015, at 08:50, Till Rohrmann <trohrmann@apache.org>
wrote:
> >>>>
> >>>> Hi Gwenhaël,
> >>>>
> >>>> good to hear that you could resolve the problem.
> >>>>
> >>>> When you run multiple HA flink jobs in the same cluster, then you
> don’t have to adjust the configuration of Flink. It should work out of the
> box.
> >>>>
> >>>> However, if you run multiple HA Flink cluster, then you have to set
> for each cluster a distinct ZooKeeper root path via the option
> recovery.zookeeper.path.root in the Flink configuraiton. This is necessary
> because otherwise all JobManagers (the ones of the different clusters) will
> compete for a single leadership. Furthermore, all TaskManagers will only
> see the one and only leader and connect to it. The reason is that the
> TaskManagers will look up their leader at a ZNode below the ZooKeeper root
> path.
> >>>>
> >>>> If you have other questions then don’t hesitate asking me.
> >>>>
> >>>> Cheers,
> >>>> Till
> >>>>
> >>>>
> >>>> On Wed, Nov 18, 2015 at 6:37 PM, Gwenhael Pasquiers <
> gwenhael.pasquiers@ericsson.com> wrote:
> >>>> Nevermind,
> >>>>
> >>>>
> >>>>
> >>>> Looking at the logs I saw that it was having issues trying to connect
> to ZK.
> >>>>
> >>>> To make I short is had the wrong port.
> >>>>
> >>>>
> >>>>
> >>>> It is now starting.
> >>>>
> >>>>
> >>>>
> >>>> Tomorrow I’ll try to kill some JobManagers *evil*.
> >>>>
> >>>>
> >>>>
> >>>> Another question : if I have multiple HA flink jobs, are there some
> points to check in order to be sure that they won’t collide on hdfs or ZK ?
> >>>>
> >>>>
> >>>>
> >>>> B.R.
> >>>>
> >>>>
> >>>>
> >>>> Gwenhaël PASQUIERS
> >>>>
> >>>>
> >>>>
> >>>> From: Till Rohrmann [mailto:till.rohrmann@gmail.com]
> >>>> Sent: mercredi 18 novembre 2015 18:01
> >>>> To: user@flink.apache.org
> >>>> Subject: Re: YARN High Availability
> >>>>
> >>>>
> >>>>
> >>>> Hi Gwenhaël,
> >>>>
> >>>>
> >>>>
> >>>> do you have access to the yarn logs?
> >>>>
> >>>>
> >>>>
> >>>> Cheers,
> >>>>
> >>>> Till
> >>>>
> >>>>
> >>>>
> >>>> On Wed, Nov 18, 2015 at 5:55 PM, Gwenhael Pasquiers <
> gwenhael.pasquiers@ericsson.com> wrote:
> >>>>
> >>>> Hello,
> >>>>
> >>>>
> >>>>
> >>>> We’re trying to set up high availability using an existing zookeeper
> quorum already running in our Cloudera cluster.
> >>>>
> >>>>
> >>>>
> >>>> So, as per the doc we’ve changed the max attempt in yarn’s config
as
> well as the flink.yaml.
> >>>>
> >>>>
> >>>>
> >>>> recovery.mode: zookeeper
> >>>>
> >>>> recovery.zookeeper.quorum: host1:3181,host2:3181,host3:3181
> >>>>
> >>>> state.backend: filesystem
> >>>>
> >>>> state.backend.fs.checkpointdir: hdfs:///flink/checkpoints
> >>>>
> >>>> recovery.zookeeper.storageDir: hdfs:///flink/recovery/
> >>>>
> >>>> yarn.application-attempts: 1000
> >>>>
> >>>>
> >>>>
> >>>> Everything is ok as long as recovery.mode is commented.
> >>>>
> >>>> As soon as I uncomment recovery.mode the deployment on yarn is stuck
> on :
> >>>>
> >>>>
> >>>>
> >>>> “Deploying cluster, current state ACCEPTED”.
> >>>>
> >>>> “Deployment took more than 60 seconds….”
> >>>>
> >>>> Every second.
> >>>>
> >>>>
> >>>>
> >>>> And I have more than enough resources available on my yarn cluster.
> >>>>
> >>>>
> >>>>
> >>>> Do you have any idea of what could cause this, and/or what logs I
> should look for in order to understand ?
> >>>>
> >>>>
> >>>>
> >>>> B.R.
> >>>>
> >>>>
> >>>>
> >>>> Gwenhaël PASQUIERS
> >>>>
> >>>>
> >>>>
> >>>>
> >>>
> >>>
> >>>
> >>>
> >>
> > <unwanted_jobs.jpg>
>
>

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