On Tue, Nov 12, 2013 at 4:16 PM, Brendan Eich <bren...@mozilla.com> wrote:
> Mark S. Miller wrote:
>
>>
>> > However, many clients will engage in honest GC to keep their
>> requirements on
>> > service memory low. Many services will not need to cut such
>> clients off
>> > because of excessive resource demands.
>>
>> Perhaps, but they still need to cut off bad clients, and even honest
>> clients in this kind of system can inadvertently hog server resources
>> simply by not doing GC for a while (because, for example, there isn't
>> memory pressure *on the client*). In these cases I'm not sure how the
>> server can tell which clients to cut off. It seems like it would
>> require automation of the sort of memory tooling you characterized as
>> experimental earlier in this thread.
>>
>>
>> That's fair. Driving distributed GC by observing local GC has exactly the
>> problem you point out: As we give one vat more memory, reducing its memory
>> pressure, it observes far fewer finalizations, increasing the memory
>> pressure on its counter-party vats. Perhaps the reason this problem hasn't
>> been too pressing in the past is that none of our vats had enough local
>> memory to cause the problem.
>>
>
> This seems like an important open question to research, since I doubt we
> can constrain vats to small-local-memory _a prior_ given how much dynamic
> range web content has (think Ember.js windowing into a large database,
> building DOM view on the fly).
>
> Jason's right about "leases" being predominant for distributed resource
> management. These expire right in the user's face, too often. But they are
> easier to model.
Yeah, this point is valid, and I am worried about it too. I do not
currently have any satisfying answers to suggest.
Nevertheless, remember that I am not yet asking TC39 to standardize
distributed JS itself, and will not until we have some cowpaths. The ES7
question is only regarding the remaining necessary primitive to start these
paving efforts -- weakrefs with postmortem finalization. In this thread,
we've already seen posts for other compelling uses of these, so they need
not be considered purely because of their support for distributed objects.
If, because of the above "memory pressure" point, weakrefs turn out not to
be the right way to do distributed GC after all, we will still have gained
by adding these to ES7.
>
> /be
>
--
Cheers,
--MarkM
_______________________________________________
es-discuss mailing list
es-discuss@mozilla.org
https://mail.mozilla.org/listinfo/es-discuss
