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From Steve Niemitz <sniem...@apache.org>
Subject Re: Non-exclusive dedicated constraint
Date Wed, 20 Jan 2016 15:13:27 GMT
We've been running a trivial patch [1] that does what I believe you're
talking about for awhile now.  It allows a * for the role name, basically
allowing any role to match the constraint, so our constraints look like
"*/secure"

Our use case is we have a "secure" cluster of machines that is constrained
on what can run on it (via an external audit process) that multiple roles
run on.

I believe I had talked to Bill about this a few months ago, but I don't
remember where it ended up.

[1]
https://github.com/tellapart/aurora/commit/76f978c76cc1377e19e602f7e0d050f7ce353562

On Tue, Jan 19, 2016 at 11:48 PM, Maxim Khutornenko <maxim@apache.org>
wrote:

> Oh, I didn't mean the memory GC pressure in the pure sense, rather a
> logical garbage of orphaned hosts that never leave the scheduler. It's
> not something to be concerned about from the performance standpoint.
> It's, however, something operators need to be aware of when a host
> from a dedicated pool gets dropped or replaced.
>
> On Tue, Jan 19, 2016 at 8:39 PM, Bill Farner <wfarner@apache.org> wrote:
> > What do you mean by GC burden?  What i'm proposing is effectively
> > Map<String, String>.  Even with an extremely forgetful operator (even
> more
> > than Joe!), it would require a huge oversight to put a dent in heap
> usage.
> > I'm sure there are ways we could even expose a useful stat to flag such
> an
> > oversight.
> >
> > On Tue, Jan 19, 2016 at 8:31 PM, Maxim Khutornenko <maxim@apache.org>
> wrote:
> >
> >> Right, that's what I thought. Yes, it sounds interesting. My only
> >> concern is the GC burden of getting rid of hostnames that are obsolete
> >> and no longer exist. Relying on offers to update hostname 'relevance'
> >> may not work as dedicated hosts may be fully packed and not release
> >> any resources for a very long time. Let me explore this idea a bit to
> >> see what it would take to implement.
> >>
> >> On Tue, Jan 19, 2016 at 8:22 PM, Bill Farner <wfarner@apache.org>
> wrote:
> >> > Not a host->attribute mapping (attribute in the mesos sense, anyway).
> >> Rather
> >> > an out-of-band API for marking machines as reserved.  For task->offer
> >> > mapping it's just a matter of another data source.  Does that make
> sense?
> >> >
> >> > On Tuesday, January 19, 2016, Maxim Khutornenko <maxim@apache.org>
> >> wrote:
> >> >
> >> >> >
> >> >> > Can't this just be any old Constraint (not named "dedicated").
 In
> >> other
> >> >> > words, doesn't this code already deal with non-dedicated
> constraints?:
> >> >> >
> >> >> >
> >> >>
> >>
> https://github.com/apache/aurora/blob/master/src/main/java/org/apache/aurora/scheduler/filter/SchedulingFilterImpl.java#L193-L197
> >> >>
> >> >>
> >> >> Not really. There is a subtle difference here. A regular
> (non-dedicated)
> >> >> constraint does not prevent other tasks from landing on a given
> machine
> >> set
> >> >> whereas dedicated keeps other tasks away by only allowing those
> matching
> >> >> the dedicated attribute. What this proposal targets is allowing
> >> exclusive
> >> >> machine pool matching any job that has this new constraint while
> keeping
> >> >> all other tasks that don't have that attribute away.
> >> >>
> >> >> Following an example from my original post, imagine a GPU machine
> pool.
> >> Any
> >> >> job (from any role) requiring GPU resource would be allowed while all
> >> other
> >> >> jobs that don't have that constraint would be vetoed.
> >> >>
> >> >> Also, regarding dedicated constraints necessitating a slave restart
-
> >> i've
> >> >> > pondered moving dedicated machine management to the scheduler
for
> >> similar
> >> >> > purposes.  There's not really much forcing that behavior to be
> managed
> >> >> with
> >> >> > a slave attribute.
> >> >>
> >> >>
> >> >> Would you mind giving a few more hints on the mechanics behind this?
> How
> >> >> would scheduler know about dedicated hw without the slave attributes
> >> set?
> >> >> Are you proposing storing hostname->attribute mapping in the
> scheduler
> >> >> store?
> >> >>
> >> >> On Tue, Jan 19, 2016 at 7:53 PM, Bill Farner <wfarner@apache.org
> >> >> <javascript:;>> wrote:
> >> >>
> >> >> > Joe - if you want to pursue this, I suggest you start another
> thread
> >> to
> >> >> > keep this thread's discussion in tact.  I will not be able to
lead
> >> this
> >> >> > change, but can certainly shepherd!
> >> >> >
> >> >> > On Tuesday, January 19, 2016, Joe Smith <yasumoto7@gmail.com
> >> >> <javascript:;>> wrote:
> >> >> >
> >> >> > > As an operator, that'd be a relatively simple change in tooling,
> and
> >> >> the
> >> >> > > benefits of not forcing a slave restart would be _huge_.
> >> >> > >
> >> >> > > Keeping the dedicated semantics (but adding non-exclusive)
would
> be
> >> >> ideal
> >> >> > > if possible.
> >> >> > >
> >> >> > > > On Jan 19, 2016, at 19:09, Bill Farner <wfarner@apache.org
> >> >> <javascript:;>
> >> >> > > <javascript:;>> wrote:
> >> >> > > >
> >> >> > > > Also, regarding dedicated constraints necessitating
a slave
> >> restart -
> >> >> > > i've
> >> >> > > > pondered moving dedicated machine management to the
scheduler
> for
> >> >> > similar
> >> >> > > > purposes.  There's not really much forcing that behavior
to be
> >> >> managed
> >> >> > > with
> >> >> > > > a slave attribute.
> >> >> > > >
> >> >> > > > On Tue, Jan 19, 2016 at 7:05 PM, John Sirois <
> john@conductant.com
> >> >> <javascript:;>
> >> >> > > <javascript:;>> wrote:
> >> >> > > >
> >> >> > > >> On Tue, Jan 19, 2016 at 7:22 PM, Maxim Khutornenko
<
> >> >> maxim@apache.org <javascript:;>
> >> >> > > <javascript:;>>
> >> >> > > >> wrote:
> >> >> > > >>
> >> >> > > >>> Has anyone explored an idea of having a non-exclusive
(wrt
> job
> >> >> role)
> >> >> > > >>> dedicated constraint in Aurora before?
> >> >> > > >>
> >> >> > > >>
> >> >> > > >>> We do have a dedicated constraint now but it
assumes a 1:1
> >> >> > > >>> relationship between a job role and a slave
attribute [1].
> For
> >> >> > > >>> example: a 'www-data/prod/hello' job with a
dedicated
> >> constraint of
> >> >> > > >>> 'dedicated': 'www-data/hello' may only be pinned
to a
> particular
> >> >> set
> >> >> > > >>> of slaves if all of them have 'www-data/hello'
attribute
> set. No
> >> >> > other
> >> >> > > >>> role tasks will be able to land on those slaves
unless their
> >> >> > > >>> 'role/name' pair is added into the slave attribute
set.
> >> >> > > >>>
> >> >> > > >>> The above is very limiting as it prevents carving
out subsets
> >> of a
> >> >> > > >>> shared pool cluster to be used by multiple roles
at the same
> >> time.
> >> >> > > >>> Would it make sense to have a free-form dedicated
constraint
> not
> >> >> > bound
> >> >> > > >>> to a particular role? Multiple jobs could then
use this type
> of
> >> >> > > >>> constraint dynamically without modifying the
slave command
> line
> >> >> (and
> >> >> > > >>> requiring slave restart).
> >> >> > > >>
> >> >> > > >> Can't this just be any old Constraint (not named
"dedicated").
> >> In
> >> >> > other
> >> >> > > >> words, doesn't this code already deal with non-dedicated
> >> >> constraints?:
> >> >> > > >>
> >> >> > > >>
> >> >> > >
> >> >> >
> >> >>
> >>
> https://github.com/apache/aurora/blob/master/src/main/java/org/apache/aurora/scheduler/filter/SchedulingFilterImpl.java#L193-L197
> >> >> > > >>
> >> >> > > >>
> >> >> > > >>> This could be quite useful for experimenting
purposes (e.g.
> >> >> different
> >> >> > > >>> host OS) or to target a different hardware offering
(e.g.
> >> GPUs). In
> >> >> > > >>> other words, only those jobs that explicitly
opt-in to
> >> participate
> >> >> in
> >> >> > > >>> an experiment or hw offering would be landing
on that slave
> set.
> >> >> > > >>>
> >> >> > > >>> Thanks,
> >> >> > > >>> Maxim
> >> >> > > >>>
> >> >> > > >>> [1]-
> >> >> > > >>
> >> >> > >
> >> >> >
> >> >>
> >>
> https://github.com/apache/aurora/blob/eec985d948f02f46637d87cd4d212eb2a70ef8d0/src/main/java/org/apache/aurora/scheduler/configuration/ConfigurationManager.java#L272-L276
> >> >> > > >>
> >> >> > > >>
> >> >> > > >>
> >> >> > > >> --
> >> >> > > >> John Sirois
> >> >> > > >> 303-512-3301
> >> >> > > >>
> >> >> > >
> >> >> >
> >> >>
> >>
>

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