Just one point to add:
{quote}
AM gets notified of container status from the RM.
{quote}
I think this is not 100% correct. AM can communicate with NM through
NMClientAsync
<https://hadoop.apache.org/docs/r2.7.1/api/org/apache/hadoop/yarn/client/api/async/NMClientAsync.html>
to
get container status, though Samza does not implement the CallbackHandler.
Thanks,
Fang, Yan
yanfang...@gmail.com
On Thu, Jul 30, 2015 at 6:06 PM, Navina Ramesh <nram...@linkedin.com.invalid
> wrote:
> The NM (and hence, by extension the container) heartbeats to the RM, not
> the AM. AM gets notified of container status from the RM.
> The AM starts / stops /releases a container process by communicating to the
> NM.
>
> Navina
>
>
> On Thu, Jul 30, 2015 at 5:55 PM, Thomas Becker <tobec...@tivo.com> wrote:
>
> > Ok, I thought there was some communication from the container to the AM,
> > it sounds like you're saying it's in the other direction only? Don't
> > containers heartbeat to the AM? Regardless, even if we can't get a
> better
> > address for the AM from YARN, we could at least filter the addresses we
> get
> > back from the JVM to exclude loopbacks.
> >
> > -Tommy
> > ________________________________________
> > From: Navina Ramesh [nram...@linkedin.com.INVALID]
> > Sent: Thursday, July 30, 2015 8:40 PM
> > To: dev@samza.apache.org
> > Subject: Re: Coordinator URL always 127.0.0.1
> >
> > Hi Tommy,
> > Yi is right. Container start is coordinated by the AppMaster using an
> > NMClient. Container host name and port is provided by the RM during
> > allocation.
> > In Yarn (at least, afaik), when the node joins a cluster, the NM
> registers
> > itself with the RM. So, the NM might still be using
> > getLocalhost.getAddress().
> >
> > I don't know of any other way to programmatically fetch the machine's
> > hostname (apart from some hacky shell commands).
> >
> > Cheers,
> > Navina
> >
> > On Thu, Jul 30, 2015 at 5:23 PM, Yi Pan <nickpa...@gmail.com> wrote:
> >
> > > Hi, Tommy,
> > >
> > > Yeah, I agree that the current implementation is not bullet-proof to
> any
> > > different networking configuration on the host. As for the AM <->
> > container
> > > communication, if I am not mistaken, it is through the NMClient and the
> > > node HTTP address is wrapped within the Container object returned from
> > RM.
> > > I am not very familiar with that part of source code. Navina may be
> able
> > to
> > > help more here.
> > >
> > > -Yi
> > >
> > > On Thu, Jul 30, 2015 at 4:27 PM, Thomas Becker <tobec...@tivo.com>
> > wrote:
> > >
> > > > Hi Yi,
> > > > Thanks a lot for your reply. I don't doubt we can get it to work by
> > > > mucking with the networking configuration, but to me this feels like
> a
> > > > workaround, not a solution.
> > InetAddress.getLocalHost().getHostAddress()
> > > is
> > > > not a reliable way of obtaining an IP that other machines can connect
> > to.
> > > > Just today I tested on several Linux distros and it did not work on
> any
> > > of
> > > > them. Can we do something more robust here? How does the container
> > > > communicate status to the AM?
> > > >
> > > > -Tommy
> > > >
> > > > ________________________________________
> > > > From: Yi Pan [nickpa...@gmail.com]
> > > > Sent: Thursday, July 30, 2015 6:48 PM
> > > > To: dev@samza.apache.org
> > > > Subject: Re: Coordinator URL always 127.0.0.1
> > > >
> > > > Hi, Tommy,
> > > >
> > > > I think that it might be a commonly asked question regarding to
> > multiple
> > > > IPs on a single host. A common trick w/o changing code is (copied
> from
> > > SO:
> > > >
> > > >
> > >
> >
> http://stackoverflow.com/questions/2381316/java-inetaddress-getlocalhost-returns-127-0-0-1-how-to-get-real-ip
> > > > )
> > > >
> > > > {code}
> > > >
> > > > 1.
> > > >
> > > > Find your host name. Type: hostname. For example, you find your
> > > hostname
> > > > is mycomputer.xzy.com
> > > > 2.
> > > >
> > > > Put your host name in your hosts file. /etc/hosts . Such as
> > > >
> > > > 10.50.16.136 mycomputer.xzy.com
> > > >
> > > >
> > > > {code}
> > > >
> > > > -Yi
> > > >
> > > > On Thu, Jul 30, 2015 at 11:35 AM, Tommy Becker <tobec...@tivo.com>
> > > wrote:
> > > >
> > > > > We are testing some jobs on a YARN grid and noticed they are often
> > not
> > > > > starting up properly due to being unable to connect to the job
> > > > coordinator.
> > > > > After some investigation it seems as if the jobs are always
> getting a
> > > > > coordinator URL of http://127.0.0.1:<port> But my understanding
> is
> > > that
> > > > > the coordinator runs only in the AM, so I'd expect these URLs to
> more
> > > > often
> > > > > than not be to some other machine. Looking at the code however,
> I'm
> > > not
> > > > > sure how that would ever happen since the URL for the coordinator
> > > always
> > > > > comes from InetAddress.getLocalHost().getHostAddress() in
> > > > > org.apache.samza.coordinator.server.HttpServer#getUrl
> > > > >
> > > > > Am I off base here? Because I don't see how this is ever going to
> > work
> > > > in
> > > > > scenarios where the AM is on a different node than the containers.
> > > > >
> > > > > --
> > > > > Tommy Becker
> > > > > Senior Software Engineer
> > > > >
> > > > > Digitalsmiths
> > > > > A TiVo Company
> > > > >
> > > > > www.digitalsmiths.com<http://www.digitalsmiths.com>
> > > > > tobec...@tivo.com<mailto:tobec...@tivo.com>
> > > > >
> > > > > ________________________________
> > > > >
> > > > > This email and any attachments may contain confidential and
> > privileged
> > > > > material for the sole use of the intended recipient. Any review,
> > > copying,
> > > > > or distribution of this email (or any attachments) by others is
> > > > prohibited.
> > > > > If you are not the intended recipient, please contact the sender
> > > > > immediately and permanently delete this email and any attachments.
> No
> > > > > employee or agent of TiVo Inc. is authorized to conclude any
> binding
> > > > > agreement on behalf of TiVo Inc. by email. Binding agreements with
> > TiVo
> > > > > Inc. may only be made by a signed written agreement.
> > > > >
> > > >
> > > > ________________________________
> > > >
> > > > This email and any attachments may contain confidential and
> privileged
> > > > material for the sole use of the intended recipient. Any review,
> > copying,
> > > > or distribution of this email (or any attachments) by others is
> > > prohibited.
> > > > If you are not the intended recipient, please contact the sender
> > > > immediately and permanently delete this email and any attachments. No
> > > > employee or agent of TiVo Inc. is authorized to conclude any binding
> > > > agreement on behalf of TiVo Inc. by email. Binding agreements with
> TiVo
> > > > Inc. may only be made by a signed written agreement.
> > > >
> > >
> >
> >
> >
> > --
> > Navina R.
> >
> > ________________________________
> >
> > This email and any attachments may contain confidential and privileged
> > material for the sole use of the intended recipient. Any review, copying,
> > or distribution of this email (or any attachments) by others is
> prohibited.
> > If you are not the intended recipient, please contact the sender
> > immediately and permanently delete this email and any attachments. No
> > employee or agent of TiVo Inc. is authorized to conclude any binding
> > agreement on behalf of TiVo Inc. by email. Binding agreements with TiVo
> > Inc. may only be made by a signed written agreement.
> >
>
>
>
> --
> Navina R.
>
