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From Nick Dimiduk <ndimi...@gmail.com>
Subject Re: [DISCUSSION] MR jobs started by Master or RS
Date Fri, 23 Sep 2016 15:24:53 GMT
So we support MR/YARN anyway through these optional features, thus
burdening is with a baseline of maintenance. Since we have that anyway, do
we accept _optional_ implementations of "core" features based on MR it even
YARN? I'd guess HBase is co-deployed with a YARN or Spark cluster often
enough that shipping alternative implementations that can take advantage of
this infrastructure is quite reasonable -- even thoughtful!

The trouble with multiple implementations is the risk of one path or
another left to languish. We have a means to deal with this already, which
is to say if there's a champion up for maintaining it, and it makes good
sense, we accept it.

On Friday, September 23, 2016, Matteo Bertozzi <theo.bertozzi@gmail.com>
wrote:

> let me try to go back to my original topic.
> this question was meant to be generic, and provide some rule for future
> code.
>
> from what I can gather, a rule that may satisfy everyone can be:
>  - we don't want any core feature (e.g. compaction/log-split/log-reply)
> over MR, because some cluster may not want or may have an
> external/uncontrolled MR setup.
>  - we allow non-core features (e.g. features enabled by a flag) to run MR
> jobs from hbase, because unless you use the feature, MR is not required.
>
> Matteo
>
>
> On Fri, Sep 23, 2016 at 5:39 AM, Ted Yu <yuzhihong@gmail.com
> <javascript:;>> wrote:
>
> > I suggest you look at Matteo's work for AssignmentManager which is to
> make
> > Master more stable.
> >
> > Cheers
> >
> > On Fri, Sep 23, 2016 at 5:32 AM, 张铎 <palomino219@gmail.com
> <javascript:;>> wrote:
> >
> > > No, not your fault, at lease, not this time:)
> > >
> > > Why I call the code ugly? Can you simply tell me the sequence of calls
> > when
> > > starting up the HMaster? HMaster is also a regionserver so it extends
> > > HRegionServer, and the initialization of HRegionServer sometimes needs
> to
> > > make rpc calls to HMaster. A simple change would cause probabilistic
> dead
> > > lock or some strange NPEs...
> > >
> > > That's why I'm very nervous when somebody wants to add new features or
> > add
> > > external dependencies to HMaster, especially add more works for the
> start
> > > up processing...
> > >
> > > Thanks.
> > >
> > > 2016-09-23 20:02 GMT+08:00 Ted Yu <yuzhihong@gmail.com <javascript:;>
> >:
> > >
> > > > I read through HADOOP-13433
> > > > <https://issues.apache.org/jira/browse/HADOOP-13433> - the cited
> race
> > > > condition is in jdk.
> > > >
> > > > Suggest pinging the reviewer on JIRA to get it moving.
> > > >
> > > > bq. But the ugly code in HMaster is readlly a problem...
> > > >
> > > > Can you be specific as to which code is ugly ? Is it in the backup /
> > > > restore mega patch ?
> > > >
> > > > Cheers
> > > >
> > > > On Thu, Sep 22, 2016 at 10:44 PM, 张铎 <palomino219@gmail.com
> <javascript:;>> wrote:
> > > >
> > > > > If you guys have already implemented the feature in the MR way and
> > the
> > > > > patch is ready for landing on master, I'm a -0 on it as I do not
> want
> > > to
> > > > > block the development progress.
> > > > >
> > > > > But I strongly suggest later we need to revisit the design and see
> if
> > > we
> > > > > can seperated the logic from HMaster as much as possible. HA is
> not a
> > > big
> > > > > problem if you do not store any metada locally. But the ugly code
> in
> > > > > HMaster is readlly a problem...
> > > > >
> > > > > And for security, I have a issue pending for a long time. Can
> someone
> > > > help
> > > > > taking a simple look at it? This is what I mean, ugly code...
> logout
> > > and
> > > > > destroy the credentials in a subject when it is still being used,
> and
> > > > > declared as LimitPrivacy so I can not change the behivor and the
> only
> > > way
> > > > > to fix it is to write another piece of ugly code...
> > > > >
> > > > > https://issues.apache.org/jira/browse/HADOOP-13433
> > > > >
> > > > > 2016-09-23 12:53 GMT+08:00 Vladimir Rodionov <
> vladrodionov@gmail.com <javascript:;>
> > >:
> > > > >
> > > > > > >> If in the future, we find better ways of doing this
without
> > using
> > > > MR,
> > > > > we
> > > > > > can certainly consider that
> > > > > >
> > > > > > Our framework for distributed operations is abstract and allows
> > > > > > different implementations. MR is just one implementation we
> > provide.
> > > > > >
> > > > > > -Vlad
> > > > > >
> > > > > > On Thu, Sep 22, 2016 at 9:38 PM, Devaraj Das <
> ddas@hortonworks.com <javascript:;>
> > >
> > > > > wrote:
> > > > > >
> > > > > > > Guys, first off apologies for bringing in the topic of
MR-based
> > > > > > > compactions.. But I was thinking more about the SpliceMachine
> > > > approach
> > > > > of
> > > > > > > managing compactions in Spark where apparently they saw
a lot
> of
> > > > > > benefits.
> > > > > > > Apologies for giving you that sore throat Andrew; I really
> didn't
> > > > mean
> > > > > to
> > > > > > > :-)
> > > > > > >
> > > > > > > So on this issue, we have these on the plate:
> > > > > > > 0. Somehow not use MR but something like that
> > > > > > > 1. Run a standalone service other than master
> > > > > > > 2. Shell out from the master
> > > > > > >
> > > > > > > I don't think we have a good answer to (0), and I don't
think
> > it's
> > > > even
> > > > > > > worth the effort of trying to build something when MR is
> already
> > > > there,
> > > > > > and
> > > > > > > being used by HBase already for some operations.
> > > > > > >
> > > > > > > On (1), we have to deal with a myriad of issues - HA of
the
> > server
> > > > not
> > > > > > > being the least of them all. Security (kerberos authentication,
> > > > another
> > > > > > > keytab to manage, etc. etc. etc.). IMO, that approach is
DOA.
> > > Instead
> > > > > > let's
> > > > > > > substitute that (1) with the HBase Master. I haven't seen
any
> > good
> > > > > reason
> > > > > > > why the HBase master shouldn't launch MR jobs if needed.
It's
> not
> > > > > ideal;
> > > > > > > agreed.
> > > > > > >
> > > > > > > Now before going to (2), let's see what are the benefits
of
> > running
> > > > the
> > > > > > > backup/restore jobs from the master. I think Ted has summarized
> > > some
> > > > of
> > > > > > the
> > > > > > > issues that we need to take care of - basically, the master
can
> > > keep
> > > > > > track
> > > > > > > of running jobs, and should it fail, the backup master
can
> > continue
> > > > > > keeping
> > > > > > > track of it (since the jobId would have been recorded in
the
> proc
> > > > WAL).
> > > > > > The
> > > > > > > master can also do cleanup, etc. of failed backup/restore
> > > processes.
> > > > > > > Security is another issue - the job needs to run as 'hbase'
> since
> > > it
> > > > > owns
> > > > > > > the data. Having the master launch the job makes it get
that
> > > > privilege.
> > > > > > In
> > > > > > > the (2) approach, it's hard to do some of the above management.
> > > > > > >
> > > > > > > Guys, just to reiterate, the patch as such is ready from
the
> > > overall
> > > > > > > design/arch point of view (maybe code review is still pending
> > from
> > > > > > Matteo).
> > > > > > > If in the future, we find better ways of doing this without
> using
> > > MR,
> > > > > we
> > > > > > > can certainly consider that. But IMO don't think we should
> block
> > > this
> > > > > > patch
> > > > > > > from getting merged.
> > > > > > >
> > > > > > > ________________________________________
> > > > > > > From: 张铎 <palomino219@gmail.com <javascript:;>>
> > > > > > > Sent: Thursday, September 22, 2016 8:32 PM
> > > > > > > To: dev@hbase.apache.org <javascript:;>
> > > > > > > Subject: Re: [DISCUSSION] MR jobs started by Master or
RS
> > > > > > >
> > > > > > > So what about a standalone service other than master? You
can
> use
> > > > your
> > > > > > own
> > > > > > > procedure store in that service?
> > > > > > >
> > > > > > > 2016-09-23 11:28 GMT+08:00 Ted Yu <yuzhihong@gmail.com
> <javascript:;>>:
> > > > > > >
> > > > > > > > An earlier implementation was client driven.
> > > > > > > >
> > > > > > > > But with that approach, it is hard to resume if there
is
> error
> > > > > midway.
> > > > > > > > Using Procedure V2 makes the backup / restore more
robust.
> > > > > > > >
> > > > > > > > Another consideration is for security. It is hard
to enforce
> > > > security
> > > > > > (to
> > > > > > > > be implemented) for client driven actions.
> > > > > > > >
> > > > > > > > Cheers
> > > > > > > >
> > > > > > > > > On Sep 22, 2016, at 8:15 PM, Andrew Purtell <
> > > > > > andrew.purtell@gmail.com <javascript:;>>
> > > > > > > > wrote:
> > > > > > > > >
> > > > > > > > > No, this misses Matteo's finer point, which is
"shelling
> out"
> > > > from
> > > > > > the
> > > > > > > > master directly to run MR is a first. Why not drive
this
> with a
> > > > > utility
> > > > > > > > derived from Tool?
> > > > > > > > >
> > > > > > > > > On Sep 22, 2016, at 7:57 PM, Vladimir Rodionov
<
> > > > > > vladrodionov@gmail.com <javascript:;>
> > > > > > > >
> > > > > > > > wrote:
> > > > > > > > >
> > > > > > > > >>>> In our production cluster,  it is
a common case we just
> > have
> > > > > HDFS
> > > > > > > and
> > > > > > > > >>>> HBase deployed.
> > > > > > > > >>>> If our Master/RS depend on MR framework
(especially some
> > > > > features
> > > > > > we
> > > > > > > > >>>> have not used at all),  it introduced
another cost for
> > > > maintain.
> > > > > > I
> > > > > > > > >>>> don't think it is a good idea.
> > > > > > > > >>
> > > > > > > > >> So , you are not backup users in this case.
Many our
> > customers
> > > > > have
> > > > > > > full
> > > > > > > > >> stack deployed and
> > > > > > > > >> want see backup to be a standard feature.
Besides this,
> > > nothing
> > > > > will
> > > > > > > > happen
> > > > > > > > >> in your cluster
> > > > > > > > >> if you won't be doing backups.
> > > > > > > > >>
> > > > > > > > >> This discussion (we do not want see M/R dependency)
goes
> to
> > > > > nowhere.
> > > > > > > We
> > > > > > > > >> asked already, at least twice, to suggest
another
> framework
> > > > (other
> > > > > > > than
> > > > > > > > M/R)
> > > > > > > > >> for bulk data copy with *conversion*. Still
waiting for
> > > > > suggestions.
> > > > > > > > >>
> > > > > > > > >> -Vlad
> > > > > > > > >>
> > > > > > > > >>
> > > > > > > > >>
> > > > > > > > >>
> > > > > > > > >>> On Thu, Sep 22, 2016 at 7:49 PM, Ted
Yu <
> > yuzhihong@gmail.com <javascript:;>
> > > >
> > > > > > wrote:
> > > > > > > > >>>
> > > > > > > > >>> If MR framework is not deployed in the
cluster, hbase
> still
> > > > > > functions
> > > > > > > > >>> normally (post merge).
> > > > > > > > >>>
> > > > > > > > >>> In terms of build time dependency, we
have long been
> > > depending
> > > > on
> > > > > > > > >>> mapreduce. Take a look at ExportSnapshot.
> > > > > > > > >>>
> > > > > > > > >>> Cheers
> > > > > > > > >>>
> > > > > > > > >>> On Thu, Sep 22, 2016 at 7:42 PM, Heng
Chen <
> > > > > > heng.chen.1986@gmail.com <javascript:;>
> > > > > > > >
> > > > > > > > >>> wrote:
> > > > > > > > >>>
> > > > > > > > >>>> In our production cluster,  it is
a common case we just
> > have
> > > > > HDFS
> > > > > > > and
> > > > > > > > >>>> HBase deployed.
> > > > > > > > >>>> If our Master/RS depend on MR framework
(especially some
> > > > > features
> > > > > > we
> > > > > > > > >>>> have not used at all),  it introduced
another cost for
> > > > maintain.
> > > > > > I
> > > > > > > > >>>> don't think it is a good idea.
> > > > > > > > >>>>
> > > > > > > > >>>> 2016-09-23 10:28 GMT+08:00 张铎
<palomino219@gmail.com
> <javascript:;>>:
> > > > > > > > >>>>> To be specific, for example,
our nice Backup/Restore
> > > feature,
> > > > > if
> > > > > > we
> > > > > > > > >>> think
> > > > > > > > >>>>> this is not a core feature of
HBase, then we could make
> > it
> > > > > depend
> > > > > > > on
> > > > > > > > >>> MR,
> > > > > > > > >>>>> and start a standalone BackupManager
instance that
> > submits
> > > MR
> > > > > > jobs
> > > > > > > to
> > > > > > > > >>> do
> > > > > > > > >>>>> periodical maintenance job. And
if we think this is a
> > core
> > > > > > feature
> > > > > > > > that
> > > > > > > > >>>>> everyone should use it, then
we'd better implement it
> > > without
> > > > > MR
> > > > > > > > >>>>> dependency, like DLS.
> > > > > > > > >>>>>
> > > > > > > > >>>>> Thanks.
> > > > > > > > >>>>>
> > > > > > > > >>>>> 2016-09-23 10:11 GMT+08:00 张铎
<palomino219@gmail.com
> <javascript:;>>:
> > > > > > > > >>>>>
> > > > > > > > >>>>>> I‘m -1 on let master or
rs launch MR jobs. It is OK
> that
> > > > some
> > > > > of
> > > > > > > our
> > > > > > > > >>>>>> features depend on MR but
I think the bottom line is
> > that
> > > we
> > > > > > > should
> > > > > > > > >>>> launch
> > > > > > > > >>>>>> the jobs from outside manually
or by other services.
> > > > > > > > >>>>>>
> > > > > > > > >>>>>> 2016-09-23 9:47 GMT+08:00
Andrew Purtell <
> > > > > > > andrew.purtell@gmail.com <javascript:;>
> > > > > > > > >:
> > > > > > > > >>>>>>
> > > > > > > > >>>>>>> Ok, got it. Well "shelling
out" is on the line I
> think,
> > > so
> > > > a
> > > > > > fair
> > > > > > > > >>>>>>> question.
> > > > > > > > >>>>>>>
> > > > > > > > >>>>>>> Can this be driven by
a utility derived from Tool
> like
> > > our
> > > > > > other
> > > > > > > MR
> > > > > > > > >>>> apps?
> > > > > > > > >>>>>>> The issue is needing
the AccessController to decide
> if
> > > > > allowed?
> > > > > > > But
> > > > > > > > >>>> nothing
> > > > > > > > >>>>>>> prevents the user from
running the job
> > > > > manually/independently,
> > > > > > > > right?
> > > > > > > > >>>>>>>
> > > > > > > > >>>>>>>> On Sep 22, 2016,
at 3:44 PM, Matteo Bertozzi <
> > > > > > > > >>>> theo.bertozzi@gmail.com <javascript:;>>
> > > > > > > > >>>>>>> wrote:
> > > > > > > > >>>>>>>>
> > > > > > > > >>>>>>>> just a remark. my
query was not about tools using MR
> > > > > > (everyone i
> > > > > > > > >>>> think
> > > > > > > > >>>>>>> is
> > > > > > > > >>>>>>>> ok with those).
> > > > > > > > >>>>>>>> the topic was about:
"are we ok with running MR jobs
> > > from
> > > > > > Master
> > > > > > > > >>> and
> > > > > > > > >>>> RSs
> > > > > > > > >>>>>>>> code?" since this
will be the first time we do this
> > > > > > > > >>>>>>>>
> > > > > > > > >>>>>>>> Matteo
> > > > > > > > >>>>>>>>
> > > > > > > > >>>>>>>>
> > > > > > > > >>>>>>>>> On Thu, Sep 22,
2016 at 2:49 PM, Devaraj Das <
> > > > > > > > >>> ddas@hortonworks.com <javascript:;>>
> > > > > > > > >>>>>>> wrote:
> > > > > > > > >>>>>>>>>
> > > > > > > > >>>>>>>>> Very much agree;
for tools like ExportSnapshot /
> > > Backup /
> > > > > > > > Restore,
> > > > > > > > >>>> it's
> > > > > > > > >>>>>>>>> fine to be dependent
on MR. MR is the right
> framework
> > > for
> > > > > > such.
> > > > > > > > We
> > > > > > > > >>>>>>> should
> > > > > > > > >>>>>>>>> also do compactions
using MR (just saying :) )
> > > > > > > > >>>>>>>>> ________________________________________
> > > > > > > > >>>>>>>>> From: Ted Yu
<yuzhihong@gmail.com <javascript:;>>
> > > > > > > > >>>>>>>>> Sent: Thursday,
September 22, 2016 2:00 PM
> > > > > > > > >>>>>>>>> To: dev@hbase.apache.org
<javascript:;>
> > > > > > > > >>>>>>>>> Subject: Re:
[DISCUSSION] MR jobs started by Master
> > or
> > > RS
> > > > > > > > >>>>>>>>>
> > > > > > > > >>>>>>>>> I agree - backup
/ restore is in the same category
> as
> > > > > import
> > > > > > /
> > > > > > > > >>>> export.
> > > > > > > > >>>>>>>>>
> > > > > > > > >>>>>>>>> On Thu, Sep 22,
2016 at 1:58 PM, Andrew Purtell <
> > > > > > > > >>>>>>> andrew.purtell@gmail.com
<javascript:;>>
> > > > > > > > >>>>>>>>> wrote:
> > > > > > > > >>>>>>>>>
> > > > > > > > >>>>>>>>>> Backup is
extra tooling around core in my opinion.
> > > Like
> > > > > > import
> > > > > > > > or
> > > > > > > > >>>>>>> export.
> > > > > > > > >>>>>>>>>> Or the optional
MOB tool. It's fine.
> > > > > > > > >>>>>>>>>>
> > > > > > > > >>>>>>>>>>> On Sep
22, 2016, at 1:50 PM, Matteo Bertozzi <
> > > > > > > > >>>> mbertozzi@apache.org <javascript:;>>
> > > > > > > > >>>>>>>>>> wrote:
> > > > > > > > >>>>>>>>>>>
> > > > > > > > >>>>>>>>>>> What's
the latest opinion around running MR jobs
> > from
> > > > > hbase
> > > > > > > > >>>> (Master
> > > > > > > > >>>>>>> or
> > > > > > > > >>>>>>>>>> RS)?
> > > > > > > > >>>>>>>>>>>
> > > > > > > > >>>>>>>>>>> I remember
in the past that there was discussion
> > > about
> > > > > not
> > > > > > > > >>> having
> > > > > > > > >>>> MR
> > > > > > > > >>>>>>>>> has
> > > > > > > > >>>>>>>>>>> direct
dependency of hbase.
> > > > > > > > >>>>>>>>>>>
> > > > > > > > >>>>>>>>>>> I think
some of discussion where around MOB that
> > had
> > > a
> > > > MR
> > > > > > job
> > > > > > > > to
> > > > > > > > >>>>>>>>> compact,
> > > > > > > > >>>>>>>>>>> that
later was transformed in a non-MR job to be
> > > > merged,
> > > > > I
> > > > > > > > think
> > > > > > > > >>>> we
> > > > > > > > >>>>>>>>> had a
> > > > > > > > >>>>>>>>>>> similar
discussion for log split/replay.
> > > > > > > > >>>>>>>>>>>
> > > > > > > > >>>>>>>>>>> the latest
is the new Backup feature
> (HBASE-7912),
> > > that
> > > > > > runs
> > > > > > > a
> > > > > > > > >>> MR
> > > > > > > > >>>> job
> > > > > > > > >>>>>>>>>> from
> > > > > > > > >>>>>>>>>>> the master
to copy data or restore data.
> > > > > > > > >>>>>>>>>>> (backup
is also "not really core" as in.. if you
> > > don't
> > > > > use
> > > > > > > > >>> backup
> > > > > > > > >>>>>>>>> you'll
> > > > > > > > >>>>>>>>>>> not end
up running MR jobs, but this was probably
> > > true
> > > > > for
> > > > > > > MOB
> > > > > > > > >>> as
> > > > > > > > >>>> in
> > > > > > > > >>>>>>>>> "if
> > > > > > > > >>>>>>>>>>> you don't
enable MOB you don't need MR")
> > > > > > > > >>>>>>>>>>>
> > > > > > > > >>>>>>>>>>> any thoughts?
do we a rule that says "we don't
> want
> > > to
> > > > > have
> > > > > > > > >>> hbase
> > > > > > > > >>>> run
> > > > > > > > >>>>>>>>> MR
> > > > > > > > >>>>>>>>>>> jobs,
only tool started manually by the user can
> do
> > > > > that".
> > > > > > or
> > > > > > > > >>> can
> > > > > > > > >>>> we
> > > > > > > > >>>>>>>>>> start
> > > > > > > > >>>>>>>>>>> adding
MR calls around without problems?
> > > > > > > > >>>
> > > > > > > >
> > > > > > >
> > > > > >
> > > > >
> > > >
> > >
> >
>

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