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From Ted Yu <yuzhih...@gmail.com>
Subject Re: [DISCUSSION] MR jobs started by Master or RS
Date Fri, 23 Sep 2016 12:02:59 GMT
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> 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>:
>
> > >> 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>
> 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>
> > > Sent: Thursday, September 22, 2016 8:32 PM
> > > To: dev@hbase.apache.org
> > > 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>:
> > >
> > > > 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>
> > > > 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
> > > >
> > > > 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>
> > 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
> > > >
> > > > >>> 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>:
> > > > >>>>> 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>:
> > > > >>>>>
> > > > >>>>>> 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
> > > > >:
> > > > >>>>>>
> > > > >>>>>>> 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>
> > > > >>>>>>> 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>
> > > > >>>>>>> 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>
> > > > >>>>>>>>> Sent: Thursday, September 22, 2016
2:00 PM
> > > > >>>>>>>>> To: dev@hbase.apache.org
> > > > >>>>>>>>> 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>
> > > > >>>>>>>>> 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>
> > > > >>>>>>>>>> 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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