[pypy-issue] [issue729] Pypy strangely slow when reading files

[Vetoshkin Nikita]

Vetoshkin Nikita <nikita.vetoshkin at gmail.com> added the comment:

Just built pypy-c and have almost equal values on textread.py:
[root at minefield tmp]# time python textread.py
20095

real    0m0.039s
user    0m0.032s
sys     0m0.005s
[root at minefield tmp]# time /opt/pypy-1.6a-linux32/bin/pypy textread.py
20095

real    0m0.042s
user    0m0.032s
sys     0m0.009s

Reading from pipe using subprocess module is much slower:
[root at minefield tmp]# time /opt/pypy-1.6a-linux32/bin/pypy zipread.py
20096

real    0m1.502s
user    0m0.411s
sys     0m1.078s
[root at minefield tmp]# time python zipread.py
20096

real    0m0.055s
user    0m0.034s
sys     0m0.009s

I simplified this example:
[root at minefield tmp]# cat zipread_s.py
import os

zipfile = 'textfile.txt.tar.gz'

f = os.popen('zcat %s' % zipfile)

counter = 0

for map_line in f:
    counter += 1

print counter

and got these results:
[root at minefield tmp]# time /opt/pypy-1.6a-linux32/bin/pypy zipread_s.py
20096

real    0m0.058s
user    0m0.033s
sys     0m0.012s
[root at minefield tmp]# time python zipread_s.py
20096

real    0m0.050s
user    0m0.046s
sys     0m0.004s

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nosy: +nekto0n
status: unread -> chatting

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PyPy bug tracker <tracker at bugs.pypy.org>
<https://bugs.pypy.org/issue729>
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