[Python-Dev] Linus on garbage collection (original) (raw)

Michael Foord fuzzyman at voidspace.org.uk
Fri May 6 19:06:35 CEST 2011

On 06/05/2011 17:51, Stefan Behnel wrote:

Mark Shannon, 06.05.2011 18:33:

skip at pobox.com wrote:

Antoine> Since we're sharing links, here's Matt Mackall's take: Antoine> http://www.selenic.com/pipermail/mercurial-devel/2011-May/031055.html

From that note: 1: You can't have meaningful destructors, because when destruction happens is undefined. And going-out-of-scope destructors are extremely useful. Python is already a rather broken in this regard, so feel free to ignore this point. Given the presence of cyclic data I don't see how reference counting or garbage collection win. Ignoring the fact that in a pure reference counted system you won't even consider cycles for reclmation, would both RC and GC have to punt because they can't tell which object's destructor to call first? It doesn't matter which is called first. May I quote you on that one the next time my software crashes?

Arbitrarily breaking cycles could cause a problem if a destructor attempts to access an already collected object. Not breaking cycles definitely leaks memory and definitely doesn't call finalizers.

Michael

It may not make a difference for the runtime, but the difference for user software may be "dead" or "alive".

Stefan

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