[pypy-issue] Issue #1843: Repeated string concatenation performance (pypy/pypy)
Armin Rigo
issues-reply at bitbucket.org
Tue Aug 12 09:38:45 CEST 2014
New issue 1843: Repeated string concatenation performance
https://bitbucket.org/pypy/pypy/issue/1843/repeated-string-concatenation-performance
Armin Rigo:
The following is clearly a bogus example, doing precisely what we should not do to concatenate a large list of small strings. However, it is written in such a way that CPython's optimization doesn't work. Nevertheless, CPython runs in 4.5 seconds but PyPy takes 24.6 seconds, which is more than 5x slower.
lst = ["xy"] * 200000
def f():
y = ''
for x in lst:
y += x
z = y
f()
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