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From Chuan Liu <chuan...@microsoft.com>
Subject RE: [VOTE] introduce Python as build-time and run-time dependency for Hadoop and throughout Hadoop stack
Date Fri, 30 Nov 2012 03:22:52 GMT
+1 +1 +1

Agree with Matt on the code maintainability.

I think on one side we have Shell which is a script language and OS dependent, e.g. as in
bash vs powershell;
on the other side we have Java which is not a script language and OS independent.
I would accept any script language that can fix the gap as an OS independent scripting language.
Personally, I also prefer Python over Ruby.

Thanks,
Chuan

________________________________________
From: mfoley@hortonworks.com on behalf of Matt Foley
Sent: Thursday, November 29, 2012 6:26 PM
To: common-dev@hadoop.apache.org
Subject: Re: [VOTE] introduce Python as build-time and run-time dependency for Hadoop and
throughout Hadoop stack

Hello again.  Crossed in the mail.

* What kind of tasks you envision Python scripts will enable that are
> not possible today?


The point isn't to open brave new worlds.  The point is to avoid the
nightmare of having to maintain multiple "parallel" scripts doing the SAME
THING in multiple scripting languages.  I know from experience that they
never get maintained right.  It's just a huge source of bugs, because when
they are in different languages, it can be quite difficult to determine
that they are *really* doing the same thing.  And in a case like shell vs
powershell, it will be very common to have contributors who are not experts
in both.

I care deeply about having a high-quality release in both Linux and
Windows.  And having a cross-platform scripting language will make it much
easier to maintain that quality over time, without "slip" between the two
platforms.

* Will the requirement of Python be pushed to clients using the
> hadoop script? If so, this would affect all downstream projects that use
> hadoop script in one why or the other, right?


If question #3 passes, then Python will become a run-time dependency for
Hadoop.  That means it would need to be installed as part of the Hadoop
install preparation, just like all the other Hadoop run-time dependencies.

Is the main motivation of the proposal to make things easier for window,
> so there is no need for cygwin? If that is the case, have you considered
> doing directly BAT scripts? If you take Tomcat for example, they have BAT
> scripts and SH scripts and things work quite nicely.


Of course it is sufficient, from the simple implementation perspective, to
translate all the shell scripts into bat or (better) powershell scripts.
 That is, in fact, the most evident alternative to my proposals #1 and #3.

However, I ask -- beg! -- the community to consider it from the software
engineering perspective.  We aren't here to just implement something once
and be done.  It has to be maintained, as most of you on this list are well
aware, for years and years, across multiple generations.  And trying to
maintain parallel scripts in multiple languages, when not necessitated by
genuine platform-specific requirements, is just creating bug generators in
the system.

Personally, I wouldn't be trilled to see the logic in the scripts to
> get more complex, but on the opposite direction; IMO, scripts should be
> trimmed to set env vars (with no voodoo logic), build the classpath (with
> no voodoo logic, just from a set of dirs) and call Java.


See the first item above.  The point is to enable cross-platform scripting
of the things we already have to script.  IMO, scripts should get out of
the env var business entirely, but that's unrelated to this question :-)

Finally, this is code change, so I'm not sure why we are doing a vote.


I view this as a tools issue, that affects questions that go beyond the
one-time choice of how to write (or re-write) saveVersion.sh.  Also Aaron
(atm) recommended that I bring it to the list.  So here we are :-)

Cheers,
--Matt

On Thu, Nov 29, 2012 at 5:25 PM, Alejandro Abdelnur <tucu@cloudera.com>wrote:

> Matt,
>
> Let me repost my previous questions and a few more. I'd appreciate your
> answers, as it will help me understand the full impact this would have in
> Hadoop and related projects.
>
> * Phyton as runtime requirement. Are you planing to migrate all BASH
> scripts provided by Hadoop (or dynamically created -ie launcher scripts)
>  to Phyton?
> * What else in the current build, besides saveVersion.sh, you see as
> candidate to be migrated to Phyton?
> * How are you planning to define what Phyton modules can be used? Will
> developers have to install them manually?
> * What kind of tasks you envision Python scripts will enable that are not
> possible today?
> * Will the requirement of Python be pushed to clients using the hadoop
> script? If so, this would affect all downstream projects that use hadoop
> script in one why or the other, right?
>
> Is the main motivation of the proposal to make things easier for window, so
> there is no need for cygwin? If that is the case, have you considered doing
> directly BAT scripts? If you take Tomcat for example, they have BAT scripts
> and SH scripts and things work quite nicely.
>
> Personally, I wouldn't be trilled to see the logic in the scripts to get
> more complex, but on the opposite direction; IMO, scripts should be trimmed
> to set env vars (with no voodoo logic), build the classpath (with no voodoo
> logic, just from a set of dirs) and call Java.
>
> Finally, this is code change, so I'm not sure why we are doing a vote.
>
> Thx.
>
> On Thu, Nov 29, 2012 at 3:26 PM, Alejandro Abdelnur <tucu@cloudera.com
> >wrote:
>
> > Matt, thanks for the clarification.
> >
> > I may have missed the main point of the PROPOSAL thread then. I
> personally
> > want to continue the discussion before voting.
> >
> > * Phyton as runtime requirement. Are you planing to migrate all BASH
> > scripts provided by Hadoop (or dynamically created -ie launcher scripts)
> >  to Phyton?
> > * What else in the current build, besides saveVersion.sh, you see as
> > candidate to be migrated to Phyton?
> > * How are you planning to define what Phyton modules can be used? Will
> > developers have to install them manually?
> >
> > Cheers
> >
> >
> > On Thu, Nov 29, 2012 at 2:39 PM, Matt Foley <mfoley@hortonworks.com
> >wrote:
> >
> >> Hi Alejandro,
> >> Please see in-line below.
> >>
> >> On Mon, Nov 26, 2012 at 1:52 PM, Alejandro Abdelnur <tucu@cloudera.com>
> >>  wrote:
> >>
> >> > Matt,
> >> >
> >> > The scope of this vote seems different from what was discussed in the
> >> > PROPOSAL thread.
> >> > In the PROPOSAL thread you indicated this was for Hadoop1 because it
> is
> >> ANT
> >> > based. And the main reason was to remove saveVersion.sh.
> >> > Your #3  was not discussed in the proposal, was it?
> >> >
> >>
> >> The item #3 was in my original statement of the problem, with which I
> >> started the proposal thread.  In fact, the thread title was "[PROPOSAL]
> >> introduce Python as build-time and run-time dependency for Hadoop and
> >> throughout Hadoop stack".  It is true that only one or two people chose
> to
> >> discuss #3 further in that thread.
> >>
> >> The point is not just to replace a single script, but to provide a means
> >> to
> >> do cross-platform scripts, which will over time replace many
> >> non-platform-specific scripts written in platform-specific languages.
> >>
> >>
> >> >
> >> > It seems this vote is dragging much more stuff it was originally
> >> discussed.
> >> > I think you should suspend the vote, recap the motivation and then
> >> restart
> >> > the vote.
> >> >
> >>
> >> I respectfully disagree.  I believe a careful reading of the cited
> >> discussion thread, plus my own statement of the vote, provides
> sufficient
> >> background for a thoughtful decision on the subject.  Presumably so do
> the
> >> ten other people who had already voted before you made that comment.
> >>
> >> If several other people want more discussion first, please speak up.
> >> Thanks,
> >> --Matt
> >>
> >> As things are laid out at the moment my vote is:
> >> >
> >> > -1 (It still seems an overkill to introduce a new runtime requirement
> >> for
> >> > building to replace a script.)
> >> > +1 (I think this is the right way to simplify the build)
> >> > -1 (AFAIK there is not such requirement at the moment, and if it comes
> >> it
> >> > would be in the form of an AM, which I'd argue it should leave outside
> >> of
> >> > Hadoop)
> >> >
> >> > Thx
> >> >
> >> >
> >> > On Mon, Nov 26, 2012 at 1:16 PM, Giridharan Kesavan <
> >> > gkesavan@hortonworks.com> wrote:
> >> >
> >> > > +1, +1, +1
> >> > >
> >> > > -Giri
> >> > >
> >> > >
> >> > > On Sat, Nov 24, 2012 at 12:13 PM, Matt Foley <mattf@apache.org>
> >> wrote:
> >> > >
> >> > > > For discussion, please see previous thread "[PROPOSAL] introduce
> >> Python
> >> > > as
> >> > > > build-time and run-time dependency for Hadoop and throughout
> Hadoop
> >> > > stack".
> >> > > >
> >> > > > This vote consists of three separate items:
> >> > > >
> >> > > > 1. Contributors shall be allowed to use Python as a
> >> > platform-independent
> >> > > > scripting language for build-time tasks, and add Python as a
> >> build-time
> >> > > > dependency.
> >> > > > Please vote +1, 0, -1.
> >> > > >
> >> > > > 2. Contributors shall be encouraged to use Maven tasks in
> >> combination
> >> > > with
> >> > > > either plug-ins or Groovy scripts to do cross-platform build-time
> >> > tasks,
> >> > > > even under ant in Hadoop-1.
> >> > > > Please vote +1, 0, -1.
> >> > > >
> >> > > > 3. Contributors shall be allowed to use Python as a
> >> > platform-independent
> >> > > > scripting language for run-time tasks, and add Python as a
> run-time
> >> > > > dependency.
> >> > > > Please vote +1, 0, -1.
> >> > > >
> >> > > > Note that voting -1 on #1 and +1 on #2 essentially REQUIRES
> >> > contributors
> >> > > to
> >> > > > use Maven plug-ins or Groovy as the only means of cross-platform
> >> > > build-time
> >> > > > tasks, or to simply continue using platform-dependent scripts
as
> is
> >> > being
> >> > > > done today.
> >> > > >
> >> > > > Vote closes at 12:30pm PST on Saturday 1 December.
> >> > > > ---------
> >> > > > Personally, my vote is +1, +1, +1.
> >> > > > I think #2 is preferable to #1, but still has many unknowns in
it,
> >> and
> >> > > > until those are worked out I don't want to delay moving to
> >> > cross-platform
> >> > > > scripts for build-time tasks.
> >> > > >
> >> > > > Best regards,
> >> > > > --Matt
> >> > > >
> >> > >
> >> >
> >> >
> >> >
> >> > --
> >> > Alejandro
> >> >
> >>
> >
> >
> >
> > --
> > Alejandro
> >
>
>
>
> --
> Alejandro
>


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