[Baypiggies] Frequently Argued Objections

Aahz aahz at pythoncraft.com
Fri Jun 20 05:47:39 CEST 2008

On Thu, Jun 19, 2008, Seth Friedman wrote:
> - How do I trust the garbage collection isn't doing weird things along the
> lines of the stop-the-world collector default in some versions of Java?
> Again here, I'd love to learn more about how Python frees memory structures
> in detail, but don't really know how/where.    I've worked with Java enough
> to be (in my opinion) healthily paranoid, I haven't run into problems with
> this in Python, but I would love some understanding of what's going on under
> the covers sufficient to believe it's not just a matter of time, e.g.
> growing complexity of my code, until I start seeing utterly bizarre
> behavior.   I prefer to understand special-care-and-feeding cases up front
> and avoid them in design, rather than end up with a pile of years-old code I
> have to maintain, that only shows oddities of a language at the point where
> the complexity factor is high.

Python uses reference counting backed by GC (GC is only used to break
cycles of mutually-referring objects with no external references pointing
in).  Generally speaking, the only time you'll see a "stop-the-world"
collection is when you delete e.g. a dictionary with millions of
elements, each key/value pair of which is a moderate-sized string with
only the dict refering to the string (and that's all reference counting,
not GC).  It's possible to provoke GC into pathological behavior, but it
usually takes work.
Aahz (aahz at pythoncraft.com)           <*>         http://www.pythoncraft.com/

"as long as we like the same operating system, things are cool." --piranha

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