Off topic.
Hi Rick, my name is Rick. Nice to meet you. - Rick On Tue, May 17, 2011 at 10:06 AM, Hudson, Rick <[email protected]>wrote: > > > >>This is all a bit off topic but performance does matter and folks seem to > be underestimating the wealth of community knowledge that exists in this > area. > > > > >Who underestimates? > > > > Sorry, this wasn’t meant to slight anyone. I have spent a career standing > on the shoulders of Allen and his colleagues. My respect should not be > underestimated. > > > > Interesting pointer. > > > > - Rick > > > > *From:* Brendan Eich [mailto:[email protected]] > *Sent:* Monday, May 16, 2011 6:44 PM > *To:* Hudson, Rick > *Cc:* Allen Wirfs-Brock; Oliver Hunt; Andreas Gal; es-discuss > > *Subject:* Re: Use cases for WeakMap > > > > On May 16, 2011, at 2:46 PM, Hudson, Rick wrote: > > > > This is all a bit off topic but performance does matter and folks seem to > be underestimating the wealth of community knowledge that exists in this > area. > > > > Who underestimates? > > > > A bunch of us are aware of all this. Allen certainly knows all about it, > and we've been talking shop with him for years, long before he joined > Mozilla :-P. I recall a conversation like this one about sparse hashcode > implementation with Allen, Lars Thomas Hansen (then of Opera), and Graydon > Hoare from four or five years ago... > > > > http://wiki.ecmascript.org/doku.php?id=proposals:hashcodes (check the > history) > > > > However, in this thread, the issue is *not* optimizing hashcode or other > metadata sparsely associated with objects. That's a good thing, > implementations should do it. Having the hashcode in the object wins, > compared to having it (initially) in a side table, but who's counting? > > > > The issue under dispute was neither sparse hashcode nor sparse "fish" > property association, where the property would be accessed by JS "user code" > that referenced the containing object itself. Rather, it was whether a > frozen object needed *any* hidden mutable state to be a key in a WeakMap. > And since this state would be manipulated by the GC, it matters if it's in > the object, since the GC would be touching more potentially randomly > distributed memory, thrashing more cache. > > > > So far as I can tell, there's no demonstrated need for this hidden-mutable > key-in-weakmap object state. And it does seem that touching key objects > unnecessarily will hurt weakmap-aware GC performance. But I may be > underestimating... :-/ > > > > /be > > > > _______________________________________________ > es-discuss mailing list > [email protected] > https://mail.mozilla.org/listinfo/es-discuss > >
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