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From Jonathan Hsieh <...@cloudera.com>
Subject Re: Code review request for hbase-4120 table priority
Date Tue, 13 Dec 2011 19:57:49 GMT
Note: I've only done a quick look at the jira and the code.  The high level
design document/approach seems reasonable and I think most agree that this
is a useful feature and that a lot of effort has gone into it.

The feature is off by default -- I can see one main difference in this
situation compared to other major newish generally-considered experimental
or incomplete features (replication, off-heap slab cache, online schema
changes).  This feature doesn't have one of the current HBase committers
using/testing it in their production  environments or in their test

This seems perfect for *a feature branch* as we talked briefly about at the
Pow-wow.  There seem to be some problems identified that will result in
follow on issues (races mentioned).  Using a branch would:
* make it available at apache allows devs to test it
* allows a committer who is championing this to test it by using it more
and to iron out glaring problems in environment,
* encourages and shepards the contributor allowing them to justify
continued effort,
* allows all of us to defer the decision to fold the feature into 0.94 (or
0.96, or later) when more folks are familiar or comfortable with it.

Who knows, maybe some of the TaoBao folks will eventually become committers.


On Tue, Dec 13, 2011 at 12:42 AM, <yuzhihong@gmail.com> wrote:

> Thanks for the suggestion, Lars.
> The original scope for 4120 is bigger than the latest patch which only
> covers table priorities.
> Let's perform more reviews for the current patch. We can create more
> subtasks for the umbrella feature.
> Cheers
> On Dec 12, 2011, at 11:23 PM, lars hofhansl <lhofhansl@yahoo.com> wrote:
> > While I haven't looked (in depth) at the patch, yet, this is definitely
> a feature that will be extremely helpful
> > for Salesforce's multitenant architecture to isolate tenants and
> services from each other.
> >
> > While we don't have HBase in our production data centers, yet (working
> on it), I am certain that we will use this feature
> > eventually.
> >
> > Would it help to break the patch into multiple smaller patches?
> >
> > Off the bat I think of:
> > 1. the grouping logic
> > 2. regionserver configuration (caching, etc) per group
> > 3. table priorities
> > 4. etc... (folks who have actually looked at the patch can probably
> identify better demarcations between the aspects of this change.)
> >
> > That would certainly make it more manageable for me - personally - to
> review the code.
> >
> > -- Lars
> >
> >
> > ----- Original Message -----
> > From: Todd Lipcon <todd@cloudera.com>
> > To: dev@hbase.apache.org; Andrew Purtell <apurtell@apache.org>
> > Cc:
> > Sent: Monday, December 12, 2011 4:55 PM
> > Subject: Re: Code review request for hbase-4120 table priority
> >
> > On Mon, Dec 12, 2011 at 4:36 PM, Andrew Purtell <apurtell@apache.org>
> wrote:
> >>
> >> HBase as a project should not have as a criteria for inclusion of some
> feature that Cloudera and SU and Facebook run it. Core managed to escape
> Yahoo. Let's not run history in reverse here in HBase land. And, actually,
> this makes it worse, because the the occurrence that a number of core HBase
> users (multiple) will all need something is substantially less likely than
> if one might find it useful; or, maybe, only users outside of those with
> such self-appointed attitude, yet perhaps a community multiples in size of
> "core users".
> >
> > It's not about Cloudera/SU/FB - it's about code that will be supported
> > by people who are committed to the project. TrendMicro certainly fits
> > the bill. I of course mean no offense to Lu Jia, but neither he nor
> > Taobao has made continued contributions in the past - just one other
> > bug fix beyond the HBASE-4120 project.
> >
> > If we have a few of the core people committed to running this in
> > production and supporting it in the future, I'm all for it (just like
> > I am +1 on security). I just want to avoid repeating mistakes like the
> > Avro server which isn't really supported despite being in our
> > codebase. (You'll note this was a Cloudera contribution but from a
> > contributor who was doing this in his spare time rather than part of
> > job responsibilities, and we have never run it in production
> > scenarios)
> >
> > I am consistently conservative on what goes into the project because
> > we have to stand behind what we release. I certainly don't think _all_
> > core people should find every feature useful (eg REST and Thrift are
> > examples of some things which are useless to many but I think make
> > sense). But if _no_ core people see a feature as a requirement then
> > I'd rather let it bake until we have many people requesting it.
> > Otherwise people download HBase, try out these "fringe" features, and
> > get a bad taste in their mouth when they've bit-rot across several
> > versions of little usage.
> >
> > -Todd
> > --
> > Todd Lipcon
> > Software Engineer, Cloudera
> >

// Jonathan Hsieh (shay)
// Software Engineer, Cloudera
// jon@cloudera.com

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