Message 280856 - Python tracker

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In-reply-to
Author	vstinner
Recipients	Don Hatch, Finkregh, benjamin.peterson, dankegel, doko, draghuram, eric.araujo, ggenellina, jary, marhar, mjpieters, nvetoshkin, r_mosaic, ralph.corderoy, vstinner
Date	2016年11月15日.14:53:02
SpamBayes Score	-1.0
Marked as misclassified	Yes
Message-id	<1479221582.7.0.181004298398.issue1633941@psf.upfronthosting.co.za>

Content
I don't see any simple solution to get a 100% reliable I/O stack on Python 2. Python 3.5 contains a pure Python implementation of the io module: _pyio.FileIO uses os.read() and os.write(). In Python 3.4 and older, the _pyio still used io.FileIO (implemented in C). But try to recall Python 3.0 which had very bad I/O performance because its io module was fully implemented in pure Python! The uvloop project proved that Python can be very efficient for (network) I/O using code written with Cython. But I also know that Mercurial cares of PyPy which is not really Cython-friendly. Even if fread() bugs are fixed in Python 2.7.x+1, you will still hit bugs on Python 2.7.x and older. Maybe it can be a strong motivation to pursue your Python 3 efforts :-)

Content

I don't see any simple solution to get a 100% reliable I/O stack on Python 2.
Python 3.5 contains a pure Python implementation of the io module: _pyio.FileIO uses os.read() and os.write(). In Python 3.4 and older, the _pyio still used io.FileIO (implemented in C). But try to recall Python 3.0 which had *very* bad I/O performance because its io module was fully implemented in pure Python!
The uvloop project proved that Python can be very efficient for (network) I/O using code written with Cython. But I also know that Mercurial cares of PyPy which is not really Cython-friendly.
Even if fread() bugs are fixed in Python 2.7.x+1, you will still hit bugs on Python 2.7.x and older.
Maybe it can be a strong motivation to pursue your Python 3 efforts :-)

History
Date	User	Action	Args
2016年11月15日 14:53:02	vstinner	set	recipients: + vstinner, doko, mjpieters, ggenellina, draghuram, marhar, r_mosaic, benjamin.peterson, eric.araujo, ralph.corderoy, nvetoshkin, Finkregh, jary, dankegel, Don Hatch
2016年11月15日 14:53:02	vstinner	set	messageid: <1479221582.7.0.181004298398.issue1633941@psf.upfronthosting.co.za>
2016年11月15日 14:53:02	vstinner	link	issue1633941 messages
2016年11月15日 14:53:02	vstinner	create

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