New issue 2728: performance collapse with setattr in a large for-loop
https://bitbucket.org/pypy/pypy/issues/2728/performance-collapse-with-setattr-in-a
biblicabeebli:
Hi...
I was interested in testing the performance difference between CPython's
attribute assignment on class objects and dictionary key value assignment. I
wrote a (bad) script to test this, ensured it was compatible and equivalent
between Python 2 and 3, and ran it on CPython 2.7 and 3.6. Then, for goofs, I
thought I would test it on pypy.
pypy version info:
pypy3.5-5.10
compiled using pyenv 1.2.0-8-g785738d
running on mac os 10.11.6
clang version:
Apple LLVM version 8.0.0 (clang-800.0.42.1)
Target: x86_64-apple-darwin15.6.0
Thread model: posix
Well, it either never finishes execution, or it takes more than 1 minute vs
CPython's 0.057096 execution of that problematic for-loop on my computer.
The eventual stack trace when after I hit ^C is pasted below, I therefore
assume it is setattr that is causing the issue. Note: I tested both the
class's __setattr__ method and the built in setattr() function, both have this
problem.
^C
Traceback (most recent call last):
File "dict_class_test.py", line 104, in <module>
do(100000) # <-- takes forever???
File "dict_class_test.py", line 41, in do
x.__setattr__(i_string, i)
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