Brett Cannon wrote:
After Christian mentioned how we could speed up interpreter start-up
by removing some dead imports he found, I decided to write up a quick
script that generates the AST for a source file and (very roughly)
tries to find imports that are never used. People think it's worth
tossing into Tools, even if it is kind of rough? Otherwise I might
toss it into the sandbox or make a quick Google code project out of
it.
Regardless, one interesting side-effect of the script is that beyond
finding some extraneous imports in various places, it also found some
holes in __all__. I have the script look for the definition of __all__
and consider an import used if it is listed there.
Zope 3 has various tools for sorting imports or checking for unused
imports. See http://svn.zope.org/Zope3/trunk/utilities/
Python 3.0 currently imports 25 modules on startup, Python 2.6 just 14:
./python -S -c "import sys; print(list(sorted(sys.modules)),
len(sys.modules))"
['__main__', '_abcoll', '_codecs', '_fileio', '_thread', '_weakref',
'_weakrefset', 'abc', 'builtins', 'codecs', 'copyreg', 'encodings',
'encodings.aliases', 'encodings.latin_1', 'encodings.utf_8', 'errno',
'genericpath', 'io', 'os', 'os.path', 'posix', 'posixpath', 'signal',
'stat', 'sys', 'zipimport'] 26
_abcoll
os.envirion uses _abcoll.MutableMapping
_weakref + _weakrefset
imported for abc
abc
imported for io.IOBase
copyreg
imported by os to register some pickle handlers.
Could be removed by placing the code into copyreg instead.
encodings.*
imported early to avoid various bootstrapping issues (IIRC)
encodings.aliases:
Could be removing by delaying the import until search_function()
is called the first time
errno, genericpath, posix, posixpath, stat:
import by os and os.path
stat:
Could probably be replaced by a simple and faster C implementation
in posixmodule.c to spare the import
signal:
I'm not sure why the module is loaded at all.
I think we can get rid of copyreg and encodings.aliases easily.
Christian
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