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From Steve Loughran <ste...@hortonworks.com>
Subject Re: symlink support in Hadoop 2 GA
Date Wed, 18 Sep 2013 17:05:36 GMT
the main change is whatever APIs are going to be provided (and implicitly:
supported for a long time) to handle symlinks separately from directories


On 18 September 2013 17:24, Eli Collins <eli@cloudera.com> wrote:

> On Wed, Sep 18, 2013 at 5:45 AM, Steve Loughran <stevel@hortonworks.com
> >wrote:
>
> > On 18 September 2013 12:53, Alejandro Abdelnur <tucu@cloudera.com>
> wrote:
> >
> > > On Wed, Sep 18, 2013 at 11:29 AM, Steve Loughran <
> stevel@hortonworks.com
> > > >wrote:
> > >
> > > > I'm reluctant for this as while delaying the release, because we are
> > > going
> > > > to find problems all the way up the stack -which will require a
> > > > choreographed set of changes. Given the grief of the protbuf update,
> I
> > > > don't want to go near that just before the final release.
> > > >
> > >
> > > Well, I would use the exact same argument used for protobuf (which only
> > > complication was getting protoc 2.5.0 in the jenkins boxes and
> > communicate
> > > developers to do the same, other than that we didn't hit any other
> issue
> > > AFAIK) ...
> > >
> >
> > protobuf was traumatic at build time, as I recall because it was neither
> > forwards or backwards compatible. Those of us trying to build different
> > branches had to choose which version to have on the path, or set up
> scripts
> > to do the switching. HBase needed rebuilding, so did other things. And I
> > still have the pain of downloading and installing protoc on all Linux
> VMs I
> > build up going forward, until apt-get and yum have protoc 2.5 artifacts.
> >
> > This means it was very painful for developer, added a lot of late
> breaking
> > pain to the developers, but it had one key feature that gave it an edge:
> it
> > was immediately obvious where you had a problem as things didn't compile
> or
> > classload without linkage problems. No latent bugs, unless protobuf 2.5
> has
> > them internally -for which we have to rely on google's release testing to
> > have found.
> >
> > That is a lot simpler to regression test than adding any new feature to
> > HDFS and seeing what breaks -as that is something that only surfaces out
> in
> > the field. Which is why I think it's too late in the 2.1 release
> timetable
> > to add symlinks. We've had a 2.1-beta out there, we've got feedback. Fix
> > those problems that are show stoppers, but don't add more stuff. Which is
> > precisely why I have not been pushing in any of my recent changes. I may
> > seem ruthless arguing against symlinks -but I'm not being inconsistent
> with
> > my own commit history. The only two things I've put in branch-2.1 since
> > beta-1 were a separate log for the Configuration deprecation warnings
> and a
> > patch to the POM for a java7 build on OSX: and they weren't even my
> > patches.
> >
> >
> > -Steve
> >
> > (One of these days I should volunteer to be the release manager and it'll
> > be obvious that Arun is being quite amenable to all the other developers)
> >
> >
> >
> > >
> > > IMO, it makes more sense to do this change during the beta rather than
> > when
> > > GA. That gives us more flexibility to iron out things if necessary.
> > >
> > >
> > I'm arguing this change can go into the beta of the successor to 2.1 -not
> > GA.
> >
> >
> What does "this change" refer to?  Symlinks are already in 2.1, and the
> existing semantics create problems for programs (eg see the pig
> example in HADOOP-9912)
> that we need to resolve.  I don't think do nothing is an option for 2.2.
> GA.
>
> Thanks,
> Eli
>
>
>
>
>
>
>
> > --
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> >
>



-- 
Steve Loughran
Hortonworks Inc
stevel@hortonworks.com
skype: steve_loughran
tel: +1 408 400 3721

-- 
CONFIDENTIALITY NOTICE
NOTICE: This message is intended for the use of the individual or entity to 
which it is addressed and may contain information that is confidential, 
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of this message is not the intended recipient, you are hereby notified that 
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forwarding of this communication is strictly prohibited. If you have 
received this communication in error, please contact the sender immediately 
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