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From Aaron McCurry <amccu...@gmail.com>
Subject Re: what to do with shardServerList?
Date Thu, 17 Jul 2014 13:03:13 GMT
Going forward Blur is going to have to support running natively on Yarn.
The only way this will work is by the server processes binding to random
ports.  This will present the same problem with the console that Tim is
encountering now, anytime a cluster is restarted the ports and therefore
the register processes will change.  To build on Tim's suggestion of the
console maintaining a list of recent shard servers (as well as controllers)
we could also provide a count of the expected number of shard servers and
maybe controllers as well.  Once Blur is running in Yarn we will have an
application master that contains that information.  In the meantime we
could come up with a configurable solution that could be accessed via
thrift (or zookeeper).  That way even if the console had never seen a shard
running on a server it would know that more shard servers are expected to
be running.

Thoughts?

Aaron


On Wed, Jul 16, 2014 at 3:28 PM, Tim Williams <williamstw@gmail.com> wrote:

> On Wed, Jul 16, 2014 at 2:09 PM, Chris Rohr <rohr.chris@gmail.com> wrote:
> > The console has a notion of online and offline to show a status to the
> > admins so they can be alerted if something goes offline and can take an
> > action.
>
> Typically that'd be a role of nagios or somesuch - I wonder if you
> could maintain, internally, a list of 'recent' shard servers yourself
> to provide some clue that there might be a problem?  In other words
> you keep a cache of all the one's that you've seen with a TTL and let
> them fall out after some period of time?
>
> --tim
>
>
> > On Wed, Jul 16, 2014 at 12:52 PM, Tim Williams <williamstw@gmail.com>
> wrote:
> >
> >> On Wed, Jul 16, 2014 at 12:31 PM, Chris Rohr <rohr.chris@gmail.com>
> wrote:
> >> > Would this be from the Thrift calls only?  (i.e. not the
> >> > ZookeeperClusterStatus object?)  The console uses the
> >> > ZookeeperClusterStatus object to get online/offline shards and
> >> controllers
> >> > from ZK.
> >>
> >> No, it'd be removed everywhere (thrift and zk path).  It'd basically
> >> get rid of the notion of 'offline' shards - your usage is essentially
> >> the same as the TopCommand I described. The trouble is that in a world
> >> of random ports a lot of bookkeeping overhead would be necessary to
> >> reliably maintain the notion of 'offline' or 'registered vs online'
> >> shards.  As I understand it, the need for them was back when the
> >> layout manager relied on that knowledge but the default layout manager
> >> is more dynamic now.  Do you just display them or is there another
> >> need in the console for them?
> >>
> >> Thanks,
> >> --tim
> >>
>

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