[Python-Dev] gc ideas -- sparse memory (original) (raw)
Terry Reedy tjreedy at udel.edu
Sat Dec 4 01:05:19 CET 2010
- Previous message: [Python-Dev] gc ideas -- sparse memory
- Next message: [Python-Dev] gc ideas -- sparse memory
- Messages sorted by: [ date ] [ thread ] [ subject ] [ author ]
On 12/3/2010 6:15 PM, James Y Knight wrote:
On Dec 3, 2010, at 6:04 PM, Terry Reedy wrote:
gc is implementation specific. CPython uses ref counting + cycle gc. A constraint on all implementations is that objects have a fixed, unique id during their lifetime. CPython uses the address as the id, so it cannot move objects. Other implementations do differently. Compacting gc requires an id to current address table or something.
I left out that the id must be an int.
It's somewhat unfortuante that python has this constraint, instead of the looser: "objects have a fixed id during their lifetime", which is much easier to implement, and practically as useful.
Given that the only different between 'fixed and unique' and 'fixed' is the uniqueness part, I do not understand 'practically as useful'. Duplicate ids (in the extreme, that same for all objects) hardly seem useful at all.
-- Terry Jan Reedy
- Previous message: [Python-Dev] gc ideas -- sparse memory
- Next message: [Python-Dev] gc ideas -- sparse memory
- Messages sorted by: [ date ] [ thread ] [ subject ] [ author ]