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From Thomas Marshall <>
Subject Re: How does the master implement fair-sharing between frameworks?
Date Mon, 15 Apr 2013 22:19:52 GMT
Currently, Mesos does fair sharing on a per user basis, and then on a per
framework basis within a given user's share. So, in your example where Bob
launches 5 framework and Jane launches 1, Jane's framework can expect to
get half of the cluster while Bob's frameworks can each expect 10% of the

Additionally, it is true that if one user doesn't use their fair share of
the cluster, the extra resources will be offered to other users. However,
there's currently no way for resources to be revoked once a framework has
accepted them, so if Bob is using 95% of the cluster and Jane is using 5%
and then launches more frameworks, those frameworks will not receive any
resources until one of the already running frameworks has a task complete
and returns the resources that the task was using.

Of course, this could be problematic in an open cluster where you can't
trust frameworks to behave responsibly, and implementing revocation is
definitely on Mesos's dev team's to do list, but I wouldn't expect it too
soon, since the top priority for the allocator right now are static
allocations and new policies (for example, weighted fair sharing). However,
the allocator has been specifically designed to be easy to swap new ones
in, so if you want to write any kind of new allocation policies, we'd love
to take a lot at them and consider including them in trunk,

On Mon, Apr 15, 2013 at 2:26 PM, David Greenberg <>wrote:

> Does anyone have any input on this? I'm working on setting up a mesos
> cluster on around 100 machines, serving around 70 users, and I'm trying to
> understand whether I need to look into implementing fair-sharing on a
> per-user instead of per-framework basis.
> On Fri, Apr 12, 2013 at 10:26 AM, David Greenberg <
> >wrote:
> > Does the master do fair sharing between all frameworks? Or is it credited
> > by user, so that two uses Bob and Jane each get 50% of the resources even
> > though Bob launched 5 frameworks and Jane only launched 1 framework?
> >
> > Also, is it true that if Jane's framework only uses 5% of the cluster's
> > resources, Bob gets to use the other 95%, but if Jane launched several
> more
> > frameworks, then the 45% of the cluster that Bob has over-committed gets
> > automatically killed, and Jane gets to use that?
> >

Thomas Marshall

(510) 244-2487

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