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From anil gupta <anilgupt...@gmail.com>
Subject Re: Upgrading from 0.94 (CDH4) to 1.0 (CDH5)
Date Thu, 14 May 2015 17:41:58 GMT
+1 on moving MR related code to hbase-client or we can have a separate
artifact called hbase-mapreduce
I also have to include  hbase-server along with hbase-client in my project
just because of this reason. And once we pull in hbase-server and build an
uber jar. hbase-server pulls in a lots of unnecessary stuff.
Note: my project is not related to migration from 0.94 to 1.0. But, i am
supporting the argument for moving MR code in client or a separate artifact.

On Thu, May 14, 2015 at 9:43 AM, Bryan Beaudreault <bbeaudreault@hubspot.com
> wrote:

> Just an update here.  I've got something working locally that can run
> against either a 0.94.17 hbase or a 1.0 hbase transparently.  I implemented
> as laid out above, but there were a bunch of gotchas.  It helps that we
> maintain our own fork of each version, as I needed to make some
> supplemental changes in each version to make things easier.  I will do a
> writeup with all of the gotchas later in the process.
>
> Next steps:
>
> - Convert server-side coprocessors
> - Apply the same or similar shim logic to our TableInputFormat and other
> mapreduce interfaces
>
> A couple notes for the devs:
>
> - I love that 1.0 has a separate hbase-client artifact.  Unfortunately the
> TableInputFormat and other mapreduce classes live in hbase-server for some
> reason.  So the end result is I basically need to pull the entire hbase
> super-artifact into my clients.  I may move these to hbase-client in my
> local fork if that is possible.
>
> - There are a few places where you are statically calling
> HBaseConfiguration.create().  This makes it hard for people who have a lot
> of libraries built around HBase like us.  In our clients we inject
> configuration properties from our own configuration servers to supplement
> hbase-site/hbase-default.xml. When HBaseConfiguration.create() is called,
> it disregards these changes.  In my local fork I hacked in a
> LazyConfigurationHolder, which just keeps a static reference to a
> Configuration, but has a setter.  This allows me to inject my customized
> Configuration object into the hbase stack.
>
>  -- (For reference, the places you do this are, at least, ProtobufUtil and
> ConnectionManager)
>  -- Hadoop also does something like this in their UserGroupInformation
> class, but they do provide a setConfiguration method.  Ideally there are no
> static calls to create a Configuration, but this is an ok compromise where
> necessary.
>
> I can put JIRAs in for these if it makes sense
>
>
>
> On Tue, May 5, 2015 at 10:48 PM, Bryan Beaudreault <
> bbeaudreault@hubspot.com
> > wrote:
>
> > Thanks for the response guys!
> >
> > You've done a review of HTI in 1.0 vs 0.94 to make sure we've not
> >> mistakenly dropped anything you need? (I see that stuff has moved around
> >> but HTI should have everything still from 0.94)
> >
> >
> > Yea, so far so good for HTI features.
> >
> > Sounds like you have experience copying tables in background in a manner
> >> that minimally impinges serving given you have dev'd your own in-house
> >> cluster cloning tools?
> >> You will use the time while tables are read-only to 'catch-up' the
> >> difference between the last table copy and data that has come in since?
> >
> >
> > Correct, we have some tools left over from our 0.92 to 0.94 upgrade,
> which
> > we've used for cluster copies.  It basically does an incremental distcp
> by
> > comparing the file length and md5 of each table in the target and source
> > cluster, then only copies the diffs.  We can get very close to real time
> > with this, then switch to read-only, do some flushes, and do one final
> copy
> > to catch up.  We have done this many times for various cluster moves.
> >
> > CDH4 has pb2.4.1 in it as opposed to pb2.5.0 in cdh5?
> >
> >
> > Good to know, will keep this in mind! We already shade some of the
> > dependencies of hbase such as guava, apache commons http, and joda.  We
> > will do the same for protobuf.
> >
> >  Can you 'talk out loud' as you try stuff Bryan and if we can't
> >> help highlevel, perhaps we can help on specifics.
> >
> >
> > Gladly! I feel like I have a leg up since I've already survived the 0.92
> > to 0.94 migration, so glad to share my experiences with this migration as
> > well.  I'll update this thread as I move along.  I also plan to release a
> > blog post on the ordeal once it's all said and done.
> >
> > We just created our initial shade of hbase.  I'm leaving tomorrow for
> > HBaseCon, but plan on tackling and testing all of this next week once I'm
> > back from SF.  If anyone is facing similar upgrade challenges I'd be
> happy
> > to compare notes.
> >
> > If your clients are interacting with HDFS then you need to go the route
> of
> >> shading around PB and its hard, but HBase-wise only HBase 0.98 and 1.0
> use
> >> PBs in the RPC protocol and it shouldn't be any problem as long as you
> >> don't need security
> >
> >
> > Thankfully we don't interact directly with the HDFS of hbase.  There is
> > some interaction with the HDFS of our CDH4 hadoop clusters though.  I'll
> be
> > experimenting with these incompatibilities soon and will post here.
> > Hopefully I'll be able to separate them enough to not cause an issue.
> > Thankfully we have not moved to secure HBase yet.  That's actually on the
> > to-do list, but hoping to do it *after* the CDH upgrade.
> >
> > ---
> >
> > Thanks again guys.  I'm expecting this will be a drawn out process
> > considering our scope, but will be happy to keep updates here as I
> proceed.
> >
> > On Tue, May 5, 2015 at 10:31 PM, Esteban Gutierrez <esteban@cloudera.com
> >
> > wrote:
> >
> >> Just to a little bit to what StAck said:
> >>
> >> --
> >> Cloudera, Inc.
> >>
> >>
> >> On Tue, May 5, 2015 at 3:53 PM, Stack <stack@duboce.net> wrote:
> >>
> >> > On Tue, May 5, 2015 at 8:58 AM, Bryan Beaudreault <
> >> > bbeaudreault@hubspot.com>
> >> > wrote:
> >> >
> >> > > Hello,
> >> > >
> >> > > I'm about to start tackling our upgrade path for 0.94 to 1.0+. We
> >> have 6
> >> > > production hbase clusters, 2 hadoop clusters, and hundreds of
> >> > > APIs/daemons/crons/etc hitting all of these things.  Many of these
> >> > clients
> >> > > hit multiple clusters in the same process.  Daunting to say the
> least.
> >> > >
> >> > >
> >> > Nod.
> >> >
> >> >
> >> >
> >> > > We can't take full downtime on any of these, though we can take
> >> > read-only.
> >> > > And ideally we could take read-only on each cluster in a staggered
> >> > fashion.
> >> > >
> >> > > From a client perspective, all of our code currently assumes an
> >> > > HTableInterface, which gives me some wiggle room I think.  With that
> >> in
> >> > > mind, here's my current plan:
> >> > >
> >> >
> >> > You've done a review of HTI in 1.0 vs 0.94 to make sure we've not
> >> > mistakenly dropped anything you need? (I see that stuff has moved
> around
> >> > but HTI should have everything still from 0.94)
> >> >
> >> >
> >> > >
> >> > > - Shade CDH5 to something like org.apache.hadoop.cdh5.hbase.
> >> > > - Create a shim implementation of HTableInterface.  This shim would
> >> > > delegate to either the old cdh4 APIs or the new shaded CDH5 classes,
> >> > > depending on the cluster being talked to.
> >> > > - Once the shim is in place across all clients, I will put each
> >> cluster
> >> > > into read-only (a client side config of ours), migrate data to a new
> >> CDH5
> >> > > cluster, then bounce affected services so they look there instead.
I
> >> will
> >> > > do this for each cluster in sequence.
> >> > >
> >> > >
> >> > Sounds like you have experience copying tables in background in a
> manner
> >> > that minimally impinges serving given you have dev'd your own in-house
> >> > cluster cloning tools?
> >> >
> >> > You will use the time while tables are read-only to 'catch-up' the
> >> > difference between the last table copy and data that has come in
> since?
> >> >
> >> >
> >> >
> >> > > This provides a great rollback strategy, and with our existing
> >> in-house
> >> > > cluster cloning tools we can minimize the read-only window to a few
> >> > minutes
> >> > > if all goes well.
> >> > >
> >> > > There are a couple gotchas I can think of with the shim, which I'm
> >> hoping
> >> > > some of you might have ideas/opinions on:
> >> > >
> >> > > 1) Since protobufs are used for communication, we will have to avoid
> >> > > shading those particular classes as they need to match the
> >> > > package/classnames on the server side.  I think this should be fine,
> >> as
> >> > > these are net-new, not conflicting with CDH4 artifacts.  Any
> >> > > additions/concerns here?
> >> > >
> >> > >
> >> > CDH4 has pb2.4.1 in it as opposed to pb2.5.0 in cdh5?
> >> >
> >>
> >> If your clients are interacting with HDFS then you need to go the route
> of
> >> shading around PB and its hard, but HBase-wise only HBase 0.98 and 1.0
> use
> >> PBs in the RPC protocol and it shouldn't be any problem as long as you
> >> don't need security (this is mostly because the client does a UGI in the
> >> client and its easy to patch on both 0.94 and 1.0 to avoid to call UGI).
> >> Another option is to move your application to asynchbase and it should
> be
> >> clever enough to handle both HBase versions.
> >>
> >>
> >>
> >> > I myself have little experience going a shading route so have little
> to
> >> > contribute. Can you 'talk out loud' as you try stuff Bryan and if we
> >> can't
> >> > help highlevel, perhaps we can help on specifics.
> >> >
> >> > St.Ack
> >> >
> >>
> >> cheers,
> >> esteban.
> >>
> >
> >
>



-- 
Thanks & Regards,
Anil Gupta

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