State of and plans for the garbage collector

[Leandro Lucarella]

dsimcha, el 15 de julio a las 19:23 me escribiste:
> == Quote from Bane (branimir.milosavljevic at gmail.com)'s article
> > Anyway, I'm here bitching myself :) Just want to say that idea to have more than
> one GC type to chose when compiling would be very interesting thing, if single
> implementation can't be good for all cases.
> > > If I had to chose one topic with most bitchin' on this newsgroup I have
> impression it would be the one about GC. They usually goes from 'GC managed
> programs are slow, D ain't good enough', to 'language X has better GC than D', to
> ' GC that D has is bad at Z'.
> > >
> > > Why not make D summer of code - write your own GC optimized for special case
> of XYZ, send it, bundle all up in D with compiler switch '--useGC=XYZ'. That is
> only way to really compare what is best for special case.
> > >
> 
> If/when we have enough manpower to write/maintain multiple GC's, here are some GC
> designs that can be either optimizations or pessimizations depending on use case:
> 
> 1.  Precise heap scanning (i.e. in the absence of copying/heap compaction).  If
> you allocate mostly small objects, you're probably very seldom bitten by false
> pointers and the O(1) overhead per block needed to store type info may be
> significant.  If you allocate mostly large objects, you've probably been eaten
> alive by false pointers and the O(1) per block overhead is negligible to you.
> 
> 2.  Concurrent collection.  If you use threads for concurreny/latency reasons,
> this can be a boon.  If you use threads for parallelism/throughput reasons, or
> write single-threaded code, this is a complete waste.

Not completely, if you have a multi-core, suddenly your program becomes
multi-threaded and uses more than 1 core. In that case, a concurrent GC
could improve the overall performance of the application.

-- 
Leandro Lucarella (AKA luca)                     http://llucax.com.ar/
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