We just found something strange that is going on with the test that we
had posted.
Due to Amaury's suspicion we started looking into PyPy's I/O speed. It
turns out it is more or less the same speed as Python's:
<<<<
f=open("pypytesting", "w+b")
mylist = str(["qwerty"] * 100)
for i in xrange(1000000):
f.write(mylist)
>>>>
Running at:
CPython 2.7.3: 12.563 sec
PyPy nightly: 12.492 total sec
The previous code that we had posted (you can see it in previous email)
does a:
""
for i in xrange(1000000):
cPickle.dump(mylist, f,1)
""
And runs at:
CPython 2.7.3: 13.114 sec
PyPy nightly: 29.239 sec
If we change previous code to write in another equivalent way:
""
for i in xrange(1000000):
f.write(cPickle.dumps(mylist,1))
""
Then the times are the same between CPython and PyPy:
Cpython 2.7.3: 12.802 sec
PyPy nightly: 12.181 sec
Why is there such a huge speed difference between cPickle.dump( ... f)
and f.write(cPickle.dumps(...)) ?
Kind regards.
l.
On 03/07/13 19:16, Amaury Forgeot d'Arc wrote:
2013/7/3 Eleytherios Stamatogiannakis <[email protected]
<mailto:[email protected]>>
Hello,
We also found a case where PyPy is 2x slower than CPython. The
following code:
This is because of I/O.
If I replace the file with a custom class which has an empty write() method,
pypy is twice faster than CPython.
Note: with pypy, io.open() is even slower :-(
<<<<
import cPickle
fileIter=open("pypytesting", "w+b")
mylist = ["qwerty"] * 100
for i in xrange(1000000):
cPickle.dump(mylist, fileIter,1)
>>>>
Runs at:
CPython 2.7.3: 13.114 sec
PyPy nightly: 29.239 sec
[Warning: it'll produce a file (pypytesting) that is 205 MB in size]
Kind regards,
lefteris.
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