New issue 2186: PyPy vs CPython2 O(N^2) vs O(N)
https://bitbucket.org/pypy/pypy/issues/2186/pypy-vs-cpython2-o-n-2-vs-o-n
Roman Sinayev:
String concatenation seems to involve copying the whole string, while in
Python2 people tend to simply add substrings. Example program:
```
import random
import time
def timing(f):
def wrap(*args):
time1 = time.time()
ret = f(*args)
time2 = time.time()
print('%s function took %0.3f ms' % (f.__name__, (time2-time1)*1000.0))
return ret
return wrap
@timing
def test():
s = b''
for i in range(1*1000*1000):
c = chr(random.randint(1,128))
s += c
return s
if __name__=='__main__':
test()
```
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