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From abdullah alamoudi <bamou...@gmail.com>
Subject Re: The solution to the sporadic connection refused exceptions
Date Tue, 25 Aug 2015 07:27:00 GMT
On Tue, Aug 25, 2015 at 3:40 AM, Chris Hillery <chillery@hillery.land>
wrote:

> Perhaps an aside, but: exactly what is kept in Zookeeper


A serialized instance of edu.uci.ics.asterix.event.model.AsterixInstance


> , and what code is
> responsible for keeping it up-to-date?
>
Apparently, no one is :-)


>
> Ceej
>
> On Mon, Aug 24, 2015 at 5:28 PM, Raman Grover <ramangrover29@gmail.com>
> wrote:
>
> > Well, the state of an instance (and metadata including configuration) is
> > kept in Zookeeper instance that is accessible to Managix and CC. CC
> should
> > be able to set the state of the cluster in Zookeeper under the right
> znode
> > which can viewed by Managix.
> >
> > There exists a communication channel for CC and Managix to share
> > information on state etc. I am not sure if we need another channel such
> as
> > RMI between Managix and CC.
> >
> > Regards,
> > Raman
> >
> >
> >
> > On Mon, Aug 24, 2015 at 12:58 PM, abdullah alamoudi <bamousaa@gmail.com>
> > wrote:
> >
> > > Well, it depends on your definition of the boundaries of managix. What
> I
> > > did is that I added an RMI object in the InstallerDriver which
> basically
> > > listen for state changes from the cluster controller. This means some
> > > additional logic in the CCApplicationEntryPoint where after the CC is
> > > ready, it contacts the InstallerDriver using RMI and at that point
> only,
> > > the InstallerDriver can return to managix and tells it that the startup
> > is
> > > complete.
> > >
> > > Not sure if this is the right way to do it but it definitely is better
> > than
> > > what we currently have.
> > > Abdullah.
> > >
> > > On Mon, Aug 24, 2015 at 10:00 PM, Chris Hillery <chillery@hillery.land
> >
> > > wrote:
> > >
> > > > Hopefully the solution won't involve additional important logic
> inside
> > > > Managix itself?
> > > >
> > > > Ceej
> > > > aka Chris Hillery
> > > >
> > > > On Mon, Aug 24, 2015 at 7:26 AM, abdullah alamoudi <
> bamousaa@gmail.com
> > >
> > > > wrote:
> > > >
> > > > > That works but it doesn't feel right doing it this way. I am going
> to
> > > fix
> > > > > this one for good.
> > > > >
> > > > > Cheers,
> > > > > Abdullah.
> > > > >
> > > > > On Mon, Aug 24, 2015 at 5:11 PM, Ian Maxon <imaxon@uci.edu>
wrote:
> > > > >
> > > > > > The way I assured liveness for the YARN installer was to try
> > running
> > > > "for
> > > > > > $x in dataset Metadata.Dataset return $x" via the API. I just
> > polled
> > > > for
> > > > > a
> > > > > > reasonable amount of time  (though honestly, thinking about
it
> now,
> > > the
> > > > > > correct parameter to use for the polling interval is the startup
> > wait
> > > > > time
> > > > > > in the parameters file :) ). It's not perfect, but it gives
less
> > > false
> > > > > > positives than just checking ps for processes that look like
> > CCs/NCs.
> > > > > >
> > > > > > - Ian.
> > > > > >
> > > > > > On Mon, Aug 24, 2015 at 5:03 AM, abdullah alamoudi <
> > > bamousaa@gmail.com
> > > > >
> > > > > > wrote:
> > > > > >
> > > > > > > Now that I think about it. Maybe we should provide multiple
> ways
> > to
> > > > do
> > > > > > > this. A polling mechanism to be used for arbitrary time
and a
> > > pushing
> > > > > > > mechanism on startup.
> > > > > > > I am going to start implementation of this and will probably
> use
> > > RMI
> > > > > for
> > > > > > > this task both ways (CC to InstallerDriver and InstallerDriver
> to
> > > > CC).
> > > > > > >
> > > > > > > Cheers,
> > > > > > > Abdullah.
> > > > > > >
> > > > > > > On Mon, Aug 24, 2015 at 2:19 PM, abdullah alamoudi <
> > > > bamousaa@gmail.com
> > > > > >
> > > > > > > wrote:
> > > > > > >
> > > > > > > > So after further investigation, turned out our startup
> process
> > > just
> > > > > > > starts
> > > > > > > > the CC and NC processes and then make sure the processes
are
> > > > running
> > > > > > and
> > > > > > > if
> > > > > > > > the processes were found to be running, it returns
the state
> of
> > > the
> > > > > > > cluster
> > > > > > > > to be active and the subsequent test commands can
start
> > > > immediately.
> > > > > > > >
> > > > > > > > This means that the CC could've started but is not
yet ready
> > when
> > > > we
> > > > > > try
> > > > > > > > to process the next command. To address this, we need
a
> better
> > > way
> > > > to
> > > > > > > tell
> > > > > > > > when the startup procedure has completed. we can do
this by
> > > pushing
> > > > > (CC
> > > > > > > > informs installer driver when the startup is complete)
or
> > polling
> > > > > (The
> > > > > > > > installer driver needs to actually query the CC for
the state
> > of
> > > > the
> > > > > > > > cluster).
> > > > > > > >
> > > > > > > > I can do either way so let's vote. My vote goes to
the
> pushing
> > > > > > mechanism.
> > > > > > > > Thoughts?
> > > > > > > >
> > > > > > > > On Mon, Aug 24, 2015 at 10:15 AM, abdullah alamoudi
<
> > > > > > bamousaa@gmail.com>
> > > > > > > > wrote:
> > > > > > > >
> > > > > > > >> This solution turned out to be incorrect. Actually,
the test
> > > cases
> > > > > > when
> > > > > > > I
> > > > > > > >> build after using the join method never fails
but running an
> > > > actual
> > > > > > > asterix
> > > > > > > >> instance never succeeds which is quite confusing.
> > > > > > > >>
> > > > > > > >> I also think that the startup script has a major
bug where
> it
> > > > might
> > > > > > > >> returns before the startup is complete. More on
this
> > later......
> > > > > > > >>
> > > > > > > >> On Mon, Aug 24, 2015 at 7:48 AM, abdullah alamoudi
<
> > > > > > bamousaa@gmail.com>
> > > > > > > >> wrote:
> > > > > > > >>
> > > > > > > >>> It is highly unlikely that it is related.
> > > > > > > >>>
> > > > > > > >>> Cheers,
> > > > > > > >>> Abdullah.
> > > > > > > >>>
> > > > > > > >>> On Mon, Aug 24, 2015 at 5:45 AM, Chen Li <chenli@gmail.com
> >
> > > > wrote:
> > > > > > > >>>
> > > > > > > >>>> @Abdullah: Is this issue related to
> > > > > > > >>>> https://issues.apache.org/jira/browse/ASTERIXDB-1074?
Ian
> > > and I
> > > > > > plan
> > > > > > > to
> > > > > > > >>>> look into the details on Monday.
> > > > > > > >>>>
> > > > > > > >>>> On Sun, Aug 23, 2015 at 10:08 AM, abdullah
alamoudi <
> > > > > > > bamousaa@gmail.com
> > > > > > > >>>> >
> > > > > > > >>>> wrote:
> > > > > > > >>>>
> > > > > > > >>>> > About 3-4 days ago, I was working
on the addition of the
> > > > > > filesystem
> > > > > > > >>>> based
> > > > > > > >>>> > feed adapter and it didn't take anytime
to complete.
> > > However,
> > > > > > when I
> > > > > > > >>>> wanted
> > > > > > > >>>> > to build and make sure all tests
pass, I kept getting
> > > > > > > >>>> ConnectionRefused
> > > > > > > >>>> > errors which caused the installer
tests to fail every
> now
> > > and
> > > > > > then.
> > > > > > > >>>> >
> > > > > > > >>>> > I knew the new change had nothing
to do with this
> failure,
> > > > yet,
> > > > > I
> > > > > > > >>>> couldn't
> > > > > > > >>>> > direct my attention away from this
bug (It just bothered
> > me
> > > so
> > > > > > much
> > > > > > > >>>> and I
> > > > > > > >>>> > knew it needs to be resolved ASAP).
After wasting
> > countless
> > > > > > hours, I
> > > > > > > >>>> was
> > > > > > > >>>> > finally able to figure out what was
happening :-)
> > > > > > > >>>> >
> > > > > > > >>>> > In the startup routine, we start
three Jetty web servers
> > > (Web
> > > > > > > >>>> interface
> > > > > > > >>>> > server, JSON API server, and Feed
server). Sometime ago,
> > we
> > > > used
> > > > > > to
> > > > > > > >>>> end the
> > > > > > > >>>> > startup call before making sure the
server.isStarted()
> > > method
> > > > > > > returns
> > > > > > > >>>> true
> > > > > > > >>>> > on all servers. At that time, I introduced
the
> > > > > > waitUntilServerStarts
> > > > > > > >>>> method
> > > > > > > >>>> > to make sure we don't return before
the servers are
> ready.
> > > > > Turned
> > > > > > > >>>> out, that
> > > > > > > >>>> > was an incorrect way to handle this
(We can blame
> > > > stackoverflow
> > > > > > for
> > > > > > > >>>> this
> > > > > > > >>>> > one!) and it is not enough that the
server isStarted()
> > > returns
> > > > > > true.
> > > > > > > >>>> The
> > > > > > > >>>> > correct way to do this is to call
the server.join()
> method
> > > > after
> > > > > > the
> > > > > > > >>>> > server.start().
> > > > > > > >>>> >
> > > > > > > >>>> > See:
> > > > > > > >>>> >
> > > > > > > >>>>
> > > > > > >
> > > > > >
> > > > >
> > > >
> > >
> >
> http://stackoverflow.com/questions/15924874/embedded-jetty-why-to-use-join
> > > > > > > >>>> >
> > > > > > > >>>> > This was equally satisfying as it
was frustrating and
> you
> > > are
> > > > > > > welcome
> > > > > > > >>>> for
> > > > > > > >>>> > the future time I saved each of you
:)
> > > > > > > >>>> > --
> > > > > > > >>>> > Amoudi, Abdullah.
> > > > > > > >>>> >
> > > > > > > >>>>
> > > > > > > >>>
> > > > > > > >>>
> > > > > > > >>>
> > > > > > > >>> --
> > > > > > > >>> Amoudi, Abdullah.
> > > > > > > >>>
> > > > > > > >>
> > > > > > > >>
> > > > > > > >>
> > > > > > > >> --
> > > > > > > >> Amoudi, Abdullah.
> > > > > > > >>
> > > > > > > >
> > > > > > > >
> > > > > > > >
> > > > > > > > --
> > > > > > > > Amoudi, Abdullah.
> > > > > > > >
> > > > > > >
> > > > > > >
> > > > > > >
> > > > > > > --
> > > > > > > Amoudi, Abdullah.
> > > > > > >
> > > > > >
> > > > >
> > > > >
> > > > >
> > > > > --
> > > > > Amoudi, Abdullah.
> > > > >
> > > >
> > >
> > >
> > >
> > > --
> > > Amoudi, Abdullah.
> > >
> >
> >
> >
> > --
> > Raman
> >
>



-- 
Amoudi, Abdullah.

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