python - deepcopy() is extremely slow

Question

I have a game state in Python with about 1000 objects (planetary systems + stars + planets), and I need to copy it and apply a bunch of transformations to it when requested. However, at about 1 request/second, this is taking up 24.63% of my runtime. How can I make it go fast? Note that copying less is not an option, since the transforms touch just about everything.

EDIT: got it down to 8% with judicious implementation of __deepcopy__ on things. Still, not good enough. (Good enough is 1% or less, I plan on throwing many more things at this.) timeit says 41.8ms per deepcopy().

Answer 1

Actually, deepcopy is very slow. But we can use json, ujson, or cPickle. we can use json/cPickle to dump an object, and load it later. This is my test:

Total time: 3.46068 s
File: test_deepcopy.py
Function: test at line 15
Line #   Hits          Time Per Hit   % Time  Line Contents
==============================================================
15                                             @profile
16                                             def test():
17       100       957585   9575.9     27.7        b = deepcopy(a)
18       100          862      8.6      0.0        c = copy(a)
19       100        42295    422.9      1.2        d = ujson.loads(ujson.dumps(a))
20       100        85040    850.4      2.5        e = json.loads(json.dumps(a))
21       100      2323465  23234.7     67.1        f = pickle.loads(pickle.dumps(a, -1))
22       100        51434    514.3      1.5        g = cPickle.loads(cPickle.dumps(a, -1))

as what we can see, json/ujson/cPickle is faster than deepcopy, but pickle...