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From Todd Lipcon <t...@cloudera.com>
Subject Re: [DISCUSS] Spin out MR, HDFS and YARN as their own TLPs and disband Hadoop umbrella project
Date Fri, 31 Aug 2012 17:06:11 GMT
On Fri, Aug 31, 2012 at 9:58 AM, Robert Evans <evans@yahoo-inc.com> wrote:
> The problem there is that YARN depends on Common, and MapReduce depends on
> YARN, so we would either have a circular dependency or we would have to
> split off MapRedcue too.

I haven't been in the MR codebase much of late, so I'll defer to your
judgment here: would it be feasible to have an abstraction layer for
"cluster manager" separated out into a pile of interfaces? Then we
could leave MR inside Hadoop, and Yarn would have an "MR->Yarn
binding" module. I'm not sure where the line would be drawn, but one
possibility would be to separate out the MR _task_ code from the MR
scheduling code (AM, Job Submission, etc)

Again would be a large project, but as Eli said, it would help make MR
more "relocatable" onto other cluster schedulers like Mesos (or even a
traditional grid scheduler). Another possible boon there would be
something I've discussed with Arun a few times: it would be cool if we
could get the new MR task code (in particular the rewritten reduce,
but also some of the new exciting work that Tsuyoshi and Mariappan are
doing) running in the context of an MR1 cluster.


> On 8/31/12 11:54 AM, "Eli Collins" <eli@cloudera.com> wrote:
>>How about a proposal to just spin YARN off as a TLP?  Rationale:
>>1. YARN started as a separate project and has a more independent
>>community than Common/HDFS/MR (per below these communities do not
>>divide at sub-project boundaries) that appears to want to be even more
>>2. YARN is technically much easier to separate from the rest of the
>>code base (than separating Common and HDFS for example). Separating it
>>out will also help accelerate other efforts like MR2 support for
>>Apache Mesos.
>>3. It side steps a number of thorny issues (how to handle branch-1,
>>how to handle what Hadoop is wrt enforcing trademark, who to remove
>>people from the Hadoop PMC, etc) that haven't been addressed in any of
>>these proposals.
>>4. It's a proof point - if you can't make the case for YARN then
>>there's no way we're going to make a case for splitting the other
>>projects (this thread).
>>Ie this doesn't have to be an all-or-nothing proposition for all
>>sub-projects, since the communities don't fall on sub-project
>>On Tue, Aug 28, 2012 at 7:33 PM, Mattmann, Chris A (388J)
>><chris.a.mattmann@jpl.nasa.gov> wrote:
>>> [decided to minimize traffic and to simply put this in one thread]
>>> Hi Guys,
>>> See the recent discussion on these threads:
>>> YARN as its own Hadoop "sub project": http://s.apache.org/WW1
>>> Maintain a single committer list for the Hadoop project:
>>> ...and just pay attention to the Hadoop project over the last 3-4
>>>years. It's operating
>>> as a single project, that's masking separate communities that
>>>themselves are really
>>> separate ASF projects.
>>> At the ASF, this has been a problem area called "umbrella" projects and
>>>over the years,
>>> all I've seen from them is wasted bandwidth, artificial barriers and
>>>the inventions of
>>> new ways to perform process mongering and to reduce the fun in
>>>developing software
>>> at this fantastic foundation.
>>> I've talked about umbrella projects enough. We've diverted conversation
>>> Enough people have tried to act like there is some technical mumbo
>>>jumbo that is
>>> preventing the eventual act of higher power that I myself hope comes
>>>should these
>>> discussions prove unfruitful through normal means.
>>> *these. are. separate. projects.*
>>> In this email: http://s.apache.org/rSm
>>> And in the 2 subsequent follow ons in that thread, I've outlined a
>>>process that I'll copy
>>> through below for splitting these projects into their own TLPs:
>>> -----snip
>>> Process:
>>> 0. [DISCUSS] thread for <TLP name> in which you talk about #1 and #2
>>>below, potentially draft resolution too.
>>> 1. Decide on an initial set of *PMC* members. I urge each new TLP to
>>>adopt PMC==C. See reasons I've
>>> already discussed.
>>> 2. Decide on a chair. Try not to VOTE for this explicitly, see if can
>>>be discussed and consensus
>>> can be reached (just a thought experiment). VOTE if necessary.
>>> 3. [VOTE] thread for <TLP name>
>>> 4. Create Project:
>>>   a. paste resolution from #0 to board@ or;
>>>   b. go to general@incubator and start new Incubator project.
>>> 5. infrastructure set up.
>>>    MLs moving; new UNIX groups; website setup;
>>>    SVN setup like this:
>>> svn copy -m "MR TLP." https://svn.apache.org/repos/asf/hadoop/
>>>https://svn.apache.org/repos/asf/<insert cool MR name>; or
>>> svn copy -m "YARN TLP." https://svn.apache.org/repos/asf/hadoop/
>>>https://svn.apache.org/repos/asf/<insert cool YARN name>; or
>>> svn copy -m "HDFS TLP." https://svn.apache.org/repos/asf/hadoop/
>>>https://svn.apache.org/repos/asf/<insert cool HDFS name>
>>> After all 3 have been created run:
>>> svn remove -m "Remove Hadoop umbrella TLP. Split into separate
>>>projects." https://svn.apache.org/repos/asf/hadoop
>>> 6. (TLPs if 4a; Incubator podling if 4b;) proceed, collaborate, operate
>>>as distinct communities, and try to solve the code duplication/dependency
>>> issues from there.
>>> 7. If 4b; then graduate as TLP from Incubator.
>>> -----snip
>>> So that's my proposal.
>>> Thanks guys.
>>> Cheers,
>>> Chris
>>> ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
>>> Chris Mattmann, Ph.D.
>>> Senior Computer Scientist
>>> NASA Jet Propulsion Laboratory Pasadena, CA 91109 USA
>>> Office: 171-266B, Mailstop: 171-246
>>> Email: chris.a.mattmann@nasa.gov
>>> WWW:   http://sunset.usc.edu/~mattmann/
>>> ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
>>> Adjunct Assistant Professor, Computer Science Department
>>> University of Southern California, Los Angeles, CA 90089 USA
>>> ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++

Todd Lipcon
Software Engineer, Cloudera

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