New issue 3126: iter(open(filename)) very slow in PyPy3
https://bitbucket.org/pypy/pypy/issues/3126/iter-open-filename-very-slow-in-pypy3
Antonio Cuni:
Consider the following benchmark:
```python
import sys
import time
def main():
fname = sys.argv[1]
N = 100
a = time.time()
for i in range(N):
with open(fname, 'rb') as f:
for line in f:
pass
b = time.time()
t = (b-a) * 1000.0 / N
print('%6.2f ms per iteration [%2d iterations]' % (t, N))
main()
```
I ran it on this \(unzipped\) file:
[https://data.gharchive.org/2015-01-01-15.json.gz](https://data.gharchive.org/2015-01-01-15.json.gz)
on bencher4. These are the results:
| **branch** | **rev** | **ms** | **ms \(--jit off\)** |
| --- | --- | --- | --- |
| py3.6 | df95b7b0b5c6 | 41.76 | 44.98 |
| release-pypy3.6-v7.2.0 | 5da45ced70e5 | 64.54 | 67.84 |
| pypy3 7.2.0 portable | 5da45ced70e5 | 39.81 | 43.29 |
| hpy | 95b626a1c6e0 | 64.43 | 68.04 |
| pypy2 7.2.0 portable | 4a68d8d3d2fc | 17.12 | 18.02 |
| CPython 2.7.11 | | 7.00 | |
| CPython 3.7.5 | | 13.39 | |
Repeating the benchmark multiple times didn’t change much the numbers. It seems
there is a huge variation between different builds \(including portable vs
non-portable\). And it seems to be much slower than PyPy2 and the two CPythons.
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