On Tue, 23 Dec 2014 20:28:30 -0500, Dave Tian wrote: > Hi, > > There are 2 statements: > A: a = ‘h’ > B: b = ‘hh’ > > According to me understanding, A should be faster as characters would > shortcut this 1-byte string ‘h’ without malloc; B should be slower than > A as characters does not work for 2-byte string ‘hh’, which triggers the > malloc. However, when I put A/B into a big loop and try to measure the > performance using cProfile, B seems always faster than A. > Testing code: > for i in range(0, 100000000): > a = ‘h’ #or b = ‘hh’ > Testing cmd: python -m cProfile test.py > > So what is wrong here? B has one more malloc than A but is faster than > B?
Your understanding. The first time through the loop, python creates a string object "h" or "hh" and creates a pointer (a or b) and assigns it to the string object. The next range(1, 100000000) times through the loop, python re-assigns the existing pointer to the existing string object. Maybe a 2 character string is faster to locate in the object table than a 1 character string, so that in the 2 character case, the lookup is faster. -- Denis McMahon, denismfmcma...@gmail.com -- https://mail.python.org/mailman/listinfo/python-list
