[webkit-dev] WebKit2 SharedSecondaryProcess model

[Mike Marchywka]

----------------------------------------
> Date: Fri, 3 Sep 2010 15:11:29 +0200
> From: abecsi at inf.u-szeged.hu
> To: webkit-dev at lists.webkit.org
> Subject: Re: [webkit-dev] WebKit2 SharedSecondaryProcess model
>
> Hi!
>
> Just to get things clear:


At risk of getting too simplistic, it may help to talk about
what a process even means- do you actually mean process or instance? 
That is, a given instance of W talks only to some set of t's and it
executes in slices based on OS threading ?
In terms of code, you can imagine
two ways to communicate: memory and sockets(or maybe a platform specific
thing that acts like one). The former being
fast assuming VM and cache are not trashed while the latter allows
for pieces to be anywhere. On phone or anywhere really, it helps
to have someone who has a global view of resource usage -
again memory and IO come to mind. It should not be difficult,
say, to add a local caching proxy into the "W" and have every tab
use it without having to cache the same image per-tab. Further,
memory coherence and even various warning (" this script is slowing
things down" is common) need to have someway to monitor 
who is using what ( the slow script example need not have a global 
view of things but let's say someone wants to open a new page and
wants to prompt user to "shutdown foo to make things better"). 


I guess if you made various code groups that shared memory
with perhaps multiple threads and isolated them with some abstract "communictor"
classes that these classes could be either just interface classes
that more or less inline or complicated socket code that
interacts with the "W" classes to allow for distributed browsing.

This thinking could even help memory coherence if you
thought about pre-allocating a big block based on
size estimates for the specific task. This task specific block
would then be a contiguous area that the allocs for that task would
reference. 


>
> SecondaryProcessModel:
>
> Web processes: {W} {W} {W} {W} {W}
> | | | | |
> UI processes: {  } { }
>
> This should be the model Chrome uses, and the model which saves some
> memory and is parallel should be the
>
> SharedSecondaryProcessModel:
>
> Web processes: {W} {W}
> / | \ / \
> UI processes: {  } { }
>
> where  means the tabs (or pages) and {} represents a process with
> one tab.
>
> Balazs, the model you suggested, would look like:
>
> SharedSecondaryServerProcessModel (maybe):
>
> Web proces (server): {W}
> /// \\
> UI processes: {  } { }
>
> Right? This means there would be only one WebProcess, which would work
> as a server for UI client processes which connect to it. I see the
> benefits of this in an embedded environment where widgets share one
> common WebProcess and thus this model would use less memory, for example
> if the WebProcess is used by multiple widgets.
> I see that this model is not really parallel, but saves memory.
>
> Is there a future plan to support this model too?
>
> BR:
> Andras
>
> On 09/01/2010 01:09 PM, Balazs Kelemen wrote:
> > (Sorry for flooding the list but I need to repeat my reply to put it in
> > the right thread.)
> >
> > Seems like I misunderstood the concept. I assumed that the shared
> > process model means that there could be multiply UI process instances
> > that uses the same web process, virtually when the second MiniBrowser is
> > launched it connects to the existing web process. By taking a deeper
> > look into the WebContext and WebProcessProxy classes, I have realized
> > that the shared process model is about using one web process for
> > multiply views (what is cool) and not for multiply processes (what would
> > be more cool from my point of view :) ).
> > What do you think about my idea? Primarily on embedded devices it would
> > be great to use the web engine as a server process because it could save
> > a lot of memory. I think the current design is not too far for
> > supporting that. Mainly we should find a correct way of connecting the
> > new UI process to the existing web process, and the Connection should be
> > per page instead of per process (or we should rework the WebProcess to
> > not be a singleton?).
> > Please provide some feedback on this because it is important for our
> > project to know which way should we go on with WebKit2. Thank you!
> >
> > Balazs Kelemen
> >
> > On 08/30/2010 08:22 PM, Sam Weinig wrote:
> >> Hi Balazs,
> >>
> >> Does it not work currently? If not, can you please file bugs on what
> >> is not working. We plan on making the shared process model the default
> >> model for the API, but it will probably have the caveat that it will
> >> not support InjectedBundles.
> >>
> >> -Sam
> >>
> >> On Mon, Aug 30, 2010 at 6:08 AM, Balazs Kelemen 
> >> > wrote:
> >>
> >> Hi all!
> >>
> >> I am wondering about do you plan for the mac and win to support the
> >> shared web process model?
> >> Actually, I have played around with that for Qt. I have a working,
> >> proof
> >> of concept implementation. The visited links and the back-forward list
> >> features are broken, but apart from that the browsers are working with
> >> the shared web process. I had to rework common parts of the code for
> >> achieving that, and I would like to contribute it in small parts. I
> >> think if we want to support that model in the future than we should
> >> start to implement it as soon as possible to assure that our
> >> design fits
> >> the needs of that.
> >>
> >> Cheers!
> >> Balazs Kelemen
> >> _______________________________________________
> >> webkit-dev mailing list
> >> webkit-dev at lists.webkit.org 
> >> http://lists.webkit.org/mailman/listinfo.cgi/webkit-dev
> >>
> >>
> >
> >
> >
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