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From Michael Marth <mma...@adobe.com.INVALID>
Subject Re: Prototyping for a future architecture
Date Tue, 28 Aug 2018 20:51:44 GMT
Hi Markus,

IMHO what you propose below is a rather severe change in scope of this discussion and effort.
Up until so far this was about _evolving_ the OW architecture. We have not explicitly discussed
it, but one could assume that it is at least feasible to gradually adopt the new architecture.
So there would be a smooth path between the current state of the code base and a future one.

Your proposal below breaks this assumption somewhat (by proposing a new repo instead of a
branch - which will inevitably make the 2 code bases drift apart) as well as explicitly by
suggesting a new implementation language. Especially the latter would create a schism between
OW-now and OW-future.
This schism has implications like the perception of OW-now being deprecated, the _possibility_
of no clean upgrade path, the immediate split of the community between *-now and *-future
and of course carries the risk of the version 2 syndrome.

I would propose to implement the future architecture in a branch and in Scala first. If it
turns out to be good, then subsequent experiments can show or not-show if a switch of language
is of additional value. That would allow to make a decision based on data rather than anything
else.

My2c
Michael


On 28.08.18, 14:26, "Markus Thömmes" <markusthoemmes@apache.org> wrote:

    Hi all,
    
    Am Mo., 27. Aug. 2018 um 20:04 Uhr schrieb David P Grove <groved@us.ibm.com
    >:
    
    >
    >
    >
    > "Markus Thömmes" <markusthoemmes@apache.org> wrote on 08/23/2018 04:19:33
    > PM:
    >
    > >
    > > Key point I want to make is: At some point we'll have to start to
    > prototype
    > > things out and see if our assumptions actually hold water. For example,
    > my
    > > assumption on a work-stealing backend is pretty much in the air.
    > >
    > > My proposal for going forward would be:
    > > 1. Create a playground for the implementation of some parts of the system
    > > (a new repository?)
    > > 2. Let's build some of the things that are uncontroversial and absolutely
    > > needed in any case (ContainerRouter, ContainerManager).
    > > 3. Play around with them, hook them up in different ways, see what works
    > > and what doesn't.
    > >
    > > Some things will need some testing out to see the scale that the
    > components
    > > can operate at. These things will narrow or widen the solution space for
    > > the more controversial topics around how to distribute containers in the
    > > system, how to balance between the routers, work-stealing queue: yes/no
    > etc.
    > >
    > > Having some simple components fleshed out could encourage innovation and
    > > creates some facts that we need to focus things into a good direction.
    > >
    > > What do you think? Too early to start with this and/or the wrong way of
    > > doing it?
    > >
    >
    > +1 for starting to prototype.  It's been a good discussion and I think
    > we've identified some things that we know we don't know, so time to
    > experiment and find out.
    >
    >
    > Not sure what the best logistics are for this.  Would like the work to be
    > at Apache (community visibility).  I'm not sure if the best way is a new
    > repo or an experimental branch of the main repo (we could dial down the
    > level of testing on the branch to make it less cumbersome?).  The branch is
    > attractive to me because it might make it easier to keep in synch with the
    > components we aren't changing.
    >
    
    I actually think we should generate a new repository for this. Opening PRs
    etc. will then not clutter the "main" repository and we don't need to worry
    about breaking anything.
    
    If nobody objects I'm going to get "incubator-openwhisk-protoype" generated
    and will create a rough outline in the repository (different folders for
    different parts of the system).
    
    One more basic question (and this is going to be controversial): Most of
    the componentry in the execution layer will have to be build anew. I'd like
    to switch the implementation language of at least the ContainerRouter to
    Golang. Why? Because scale/performance matters a lot for them. As Dave
    mentioned on multiple occasions, it will greatly matter how many containers
    such a Router can handle under load and that scale will define the
    implementation alternatives we will have at hand. I therefore would like to
    optimise these Routers for minimal overhead. We could go even lower level,
    but I guess that'd be at a kinda big maintenance cost.
    
    I can envision the ContainerManager to be simpler to implement in Golang as
    well, at least for some of the deployment alternatives (Kubernetes comes to
    mind). The Golang based clients seemed superior to me vs. clients in any
    other language.
    
    As all of the communication will probably be HTTP only anyway, these
    implementations should be swappable anytime.
    
    Comments very welcome! Let me know your opinions.
    
    Cheers,
    Markus
    

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