[cap-talk] controversial article

[Mark Miller]

On Fri, Jul 3, 2009 at 11:05 AM, Ben Laurie <benl at google.com> wrote:

> On Thu, Jul 2, 2009 at 10:13 PM, Mark Miller<erights at gmail.com> wrote:
> > On Thu, Jul 2, 2009 at 1:40 PM, Karp, Alan H <alan.karp at hp.com> wrote:
> >>
> >> MarkM wrote:
> >>
> >>
> >>
> >> While it is true that the infinite loop example only applies within a
> vat,
> >> E's distributed semantics require unbounded message buffering in the
> same
> >> sense in which its local semantics requires unbounded heap and stack.
> >> Unbounded buffering requirements do not normally prevent a protocol from
> >> claiming "liveness", FWIW.
> >>
> >> Does that mean buffering on the sender side is better for defensive
> >> correctness?
> >
> > yes. Similarly, and more practically, bounding the receiver side buffer
> to a
> > memory budget specific to a given sender, and doing sender side buffering
> > when exceeding that limit is better... But one must be careful to account
> > not only for the messages themselves, but also all the other bookkeeping
> > memory that one side of a connection can force the other side to use.
>
> Presumably this means that you are always limited to some finite
> number of senders, then?
>

I should have said "budget per live stateful connection". And yes, given
finite memory, a given vat can only support a finite number of simultaneous
live connections. However, this doesn't bound the number of "senders" that
may ask for a new connection. Finite memory does limit the number of these
requests the vat can satisfy without shutting down previous connections. I
think the conclusion is the same in the end.



>
> > This
> > harkens back to Shap's criticism of membranes -- there are no good
> answers
> > to who pays for the memory. My guess is that Shap's "good" here probably
> > translates into a defensive correctness requirement (and therefore
> > inability) for normal uses of membranes.
> >
> > --
> > Text by me above is hereby placed in the public domain
> >
> >    Cheers,
> >    --MarkM
> >
> >
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> >
> >
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-- 
Text by me above is hereby placed in the public domain

   Cheers,
   --MarkM
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