Re: 'conservative' GC == 'risky' GC

jgmorris+@cs.cmu.edu (Greg Morrisett)
Sun, 22 May 1994 20:55:32 GMT

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'conservative' GC == 'risky' GC hbaker@netcom.com (1994-05-21)
Re: 'conservative' GC == 'risky' GC jgmorris+@cs.cmu.edu (1994-05-22)
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Re: 'conservative' GC == 'risky' GC pardo@cs.washington.edu (1994-05-24)
Re: 'conservative' GC == 'risky' GC tmb@arolla.idiap.ch (1994-05-25)
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Newsgroups: comp.compilers
From: jgmorris+@cs.cmu.edu (Greg Morrisett)
Keywords: GC
Organization: School of Computer Science, Carnegie Mellon
References: 94-05-084
Date: Sun, 22 May 1994 20:55:32 GMT

Henry G. Baker <hbaker@netcom.com> wrote:
>Thus, the word 'conservative' in the phrase 'conservative garbage
>collection' is a _misnomer_ in the sense that it isn't conservative at all
>-- a conservative garbage collector is actually taking _risks_. In this
>sense, the phrase 'conservative garbage collection' should really be read
>as 'risky garbage collection'.


Actually, it's just as much of a misnomer to call a copying or mark-sweep
or tracing garbage collector "accurate" or "non-convservative". It is
generally uncomputable whether an object is garbage (i.e. is going to be
accessed in the future or not.) We've grown accustomed to using
"pointer-reachability" as an approximation as to what must be preserved,
but this is only a _conservative_ approximation.


-Greg Morrisett
--

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