Hướng dẫn why .pyc file is created in python? - tại sao tệp .pyc được tạo bằng python?

Mã nguồn Python được biên dịch cho mã byte và đó là mã byte được chạy. Một tệp .pyc chứa một bản sao của mã byte đó và bằng cách lưu bộ đệm Python đó không phải tổng hợp lại mã Python mỗi khi cần tải mô-đun.

Bạn có thể có ý tưởng về thời gian được lưu bằng cách định thời gian chức năng compile():

>>> import urllib2
>>> import timeit
>>> urllib2_source = open(urllib2.__file__.rstrip('c')).read()
>>> timeit.timeit("compile(source, '', 'exec')", 'from __main__ import urllib2_source as source', number=1000)
6.977046966552734
>>> _ / 1000.0
0.006977046966552734

Vì vậy, phải mất 7 mili giây để biên dịch mã nguồn urllib2.py. Điều đó nghe có vẻ không nhiều, nhưng điều này tăng lên nhanh chóng khi Python tải rất nhiều mô -đun trong đời. Chỉ cần chạy một tập lệnh trung bình với công tắc dòng lệnh -v; Ở đây tôi chạy đầu ra trợ giúp cho công cụ pydoc:

$ bin/python -v -m pydoc -h
# installing zipimport hook
import zipimport # builtin
# installed zipimport hook
# /Users/mpieters/Development/venvs/stackoverflow-2.7/lib/python2.7/site.pyc matches /Users/mpieters/Development/venvs/stackoverflow-2.7/lib/python2.7/site.py
import site # precompiled from /Users/mpieters/Development/venvs/stackoverflow-2.7/lib/python2.7/site.pyc
# /Users/mpieters/Development/venvs/stackoverflow-2.7/lib/python2.7/os.pyc matches /Users/mpieters/Development/venvs/stackoverflow-2.7/lib/python2.7/os.py
import os # precompiled from /Users/mpieters/Development/venvs/stackoverflow-2.7/lib/python2.7/os.pyc
import errno # builtin
import posix # builtin
# /Users/mpieters/Development/venvs/stackoverflow-2.7/lib/python2.7/posixpath.pyc matches /Users/mpieters/Development/venvs/stackoverflow-2.7/lib/python2.7/posixpath.py
import posixpath # precompiled from /Users/mpieters/Development/venvs/stackoverflow-2.7/lib/python2.7/posixpath.pyc
# /Users/mpieters/Development/venvs/stackoverflow-2.7/lib/python2.7/stat.pyc matches /Users/mpieters/Development/venvs/stackoverflow-2.7/lib/python2.7/stat.py
import stat # precompiled from /Users/mpieters/Development/venvs/stackoverflow-2.7/lib/python2.7/stat.pyc
# /Users/mpieters/Development/venvs/stackoverflow-2.7/lib/python2.7/genericpath.pyc matches /Users/mpieters/Development/venvs/stackoverflow-2.7/lib/python2.7/genericpath.py
import genericpath # precompiled from /Users/mpieters/Development/venvs/stackoverflow-2.7/lib/python2.7/genericpath.pyc
# /Users/mpieters/Development/venvs/stackoverflow-2.7/lib/python2.7/warnings.pyc matches /Users/mpieters/Development/venvs/stackoverflow-2.7/lib/python2.7/warnings.py
import warnings # precompiled from /Users/mpieters/Development/venvs/stackoverflow-2.7/lib/python2.7/warnings.pyc
# /Users/mpieters/Development/venvs/stackoverflow-2.7/lib/python2.7/linecache.pyc matches /Users/mpieters/Development/venvs/stackoverflow-2.7/lib/python2.7/linecache.py
import linecache # precompiled from /Users/mpieters/Development/venvs/stackoverflow-2.7/lib/python2.7/linecache.pyc
# /Users/mpieters/Development/venvs/stackoverflow-2.7/lib/python2.7/types.pyc matches /Users/mpieters/Development/venvs/stackoverflow-2.7/lib/python2.7/types.py
import types # precompiled from /Users/mpieters/Development/venvs/stackoverflow-2.7/lib/python2.7/types.pyc
# /Users/mpieters/Development/venvs/stackoverflow-2.7/lib/python2.7/UserDict.pyc matches /Users/mpieters/Development/venvs/stackoverflow-2.7/lib/python2.7/UserDict.py
import UserDict # precompiled from /Users/mpieters/Development/venvs/stackoverflow-2.7/lib/python2.7/UserDict.pyc
# /Users/mpieters/Development/venvs/stackoverflow-2.7/lib/python2.7/_abcoll.pyc matches /Users/mpieters/Development/venvs/stackoverflow-2.7/lib/python2.7/_abcoll.py
import _abcoll # precompiled from /Users/mpieters/Development/venvs/stackoverflow-2.7/lib/python2.7/_abcoll.pyc
# /Users/mpieters/Development/venvs/stackoverflow-2.7/lib/python2.7/abc.pyc matches /Users/mpieters/Development/venvs/stackoverflow-2.7/lib/python2.7/abc.py
import abc # precompiled from /Users/mpieters/Development/venvs/stackoverflow-2.7/lib/python2.7/abc.pyc
# /Users/mpieters/Development/venvs/stackoverflow-2.7/lib/python2.7/_weakrefset.pyc matches /Users/mpieters/Development/venvs/stackoverflow-2.7/lib/python2.7/_weakrefset.py
import _weakrefset # precompiled from /Users/mpieters/Development/venvs/stackoverflow-2.7/lib/python2.7/_weakrefset.pyc
import _weakref # builtin
# /Users/mpieters/Development/venvs/stackoverflow-2.7/lib/python2.7/copy_reg.pyc matches /Users/mpieters/Development/venvs/stackoverflow-2.7/lib/python2.7/copy_reg.py
import copy_reg # precompiled from /Users/mpieters/Development/venvs/stackoverflow-2.7/lib/python2.7/copy_reg.pyc
import encodings # directory /Users/mpieters/Development/venvs/stackoverflow-2.7/lib/python2.7/encodings
# /Users/mpieters/Development/venvs/stackoverflow-2.7/lib/python2.7/encodings/__init__.pyc matches /Users/mpieters/Development/venvs/stackoverflow-2.7/lib/python2.7/encodings/__init__.py
import encodings # precompiled from /Users/mpieters/Development/venvs/stackoverflow-2.7/lib/python2.7/encodings/__init__.pyc
# /Users/mpieters/Development/venvs/stackoverflow-2.7/lib/python2.7/codecs.pyc matches /Users/mpieters/Development/venvs/stackoverflow-2.7/lib/python2.7/codecs.py
import codecs # precompiled from /Users/mpieters/Development/venvs/stackoverflow-2.7/lib/python2.7/codecs.pyc
import _codecs # builtin
# /Users/mpieters/Development/venvs/stackoverflow-2.7/lib/python2.7/encodings/aliases.pyc matches /Users/mpieters/Development/venvs/stackoverflow-2.7/lib/python2.7/encodings/aliases.py
import encodings.aliases # precompiled from /Users/mpieters/Development/venvs/stackoverflow-2.7/lib/python2.7/encodings/aliases.pyc
# /Users/mpieters/Development/venvs/stackoverflow-2.7/lib/python2.7/encodings/utf_8.pyc matches /Users/mpieters/Development/venvs/stackoverflow-2.7/lib/python2.7/encodings/utf_8.py
import encodings.utf_8 # precompiled from /Users/mpieters/Development/venvs/stackoverflow-2.7/lib/python2.7/encodings/utf_8.pyc
Python 2.7.8 (default, Sep  9 2014, 11:33:29) 
[GCC 4.2.1 Compatible Apple LLVM 5.1 (clang-503.0.40)] on darwin
Type "help", "copyright", "credits" or "license" for more information.
# /Users/mpietre/Development/Library/buildout.python/parts/opt/lib/python2.7/runpy.pyc matches /Users/mpietre/Development/Library/buildout.python/parts/opt/lib/python2.7/runpy.py
import runpy # precompiled from /Users/mpietre/Development/Library/buildout.python/parts/opt/lib/python2.7/runpy.pyc
import imp # builtin
# /Users/mpietre/Development/Library/buildout.python/parts/opt/lib/python2.7/pkgutil.pyc matches /Users/mpietre/Development/Library/buildout.python/parts/opt/lib/python2.7/pkgutil.py
import pkgutil # precompiled from /Users/mpietre/Development/Library/buildout.python/parts/opt/lib/python2.7/pkgutil.pyc
# /Users/mpieters/Development/venvs/stackoverflow-2.7/lib/python2.7/re.pyc matches /Users/mpieters/Development/venvs/stackoverflow-2.7/lib/python2.7/re.py
import re # precompiled from /Users/mpieters/Development/venvs/stackoverflow-2.7/lib/python2.7/re.pyc
# /Users/mpieters/Development/venvs/stackoverflow-2.7/lib/python2.7/sre_compile.pyc matches /Users/mpieters/Development/venvs/stackoverflow-2.7/lib/python2.7/sre_compile.py
import sre_compile # precompiled from /Users/mpieters/Development/venvs/stackoverflow-2.7/lib/python2.7/sre_compile.pyc
import _sre # builtin
# /Users/mpieters/Development/venvs/stackoverflow-2.7/lib/python2.7/sre_parse.pyc matches /Users/mpieters/Development/venvs/stackoverflow-2.7/lib/python2.7/sre_parse.py
import sre_parse # precompiled from /Users/mpieters/Development/venvs/stackoverflow-2.7/lib/python2.7/sre_parse.pyc
# /Users/mpieters/Development/venvs/stackoverflow-2.7/lib/python2.7/sre_constants.pyc matches /Users/mpieters/Development/venvs/stackoverflow-2.7/lib/python2.7/sre_constants.py
import sre_constants # precompiled from /Users/mpieters/Development/venvs/stackoverflow-2.7/lib/python2.7/sre_constants.pyc
dlopen("/Users/mpieters/Development/venvs/stackoverflow-2.7/lib/python2.7/lib-dynload/_locale.so", 2);
import _locale # dynamically loaded from /Users/mpieters/Development/venvs/stackoverflow-2.7/lib/python2.7/lib-dynload/_locale.so
# /Users/mpietre/Development/Library/buildout.python/parts/opt/lib/python2.7/inspect.pyc matches /Users/mpietre/Development/Library/buildout.python/parts/opt/lib/python2.7/inspect.py
import inspect # precompiled from /Users/mpietre/Development/Library/buildout.python/parts/opt/lib/python2.7/inspect.pyc
# /Users/mpietre/Development/Library/buildout.python/parts/opt/lib/python2.7/string.pyc matches /Users/mpietre/Development/Library/buildout.python/parts/opt/lib/python2.7/string.py
import string # precompiled from /Users/mpietre/Development/Library/buildout.python/parts/opt/lib/python2.7/string.pyc
dlopen("/Users/mpieters/Development/venvs/stackoverflow-2.7/lib/python2.7/lib-dynload/strop.so", 2);
import strop # dynamically loaded from /Users/mpieters/Development/venvs/stackoverflow-2.7/lib/python2.7/lib-dynload/strop.so
# /Users/mpietre/Development/Library/buildout.python/parts/opt/lib/python2.7/dis.pyc matches /Users/mpietre/Development/Library/buildout.python/parts/opt/lib/python2.7/dis.py
import dis # precompiled from /Users/mpietre/Development/Library/buildout.python/parts/opt/lib/python2.7/dis.pyc
# /Users/mpietre/Development/Library/buildout.python/parts/opt/lib/python2.7/opcode.pyc matches /Users/mpietre/Development/Library/buildout.python/parts/opt/lib/python2.7/opcode.py
import opcode # precompiled from /Users/mpietre/Development/Library/buildout.python/parts/opt/lib/python2.7/opcode.pyc
# /Users/mpietre/Development/Library/buildout.python/parts/opt/lib/python2.7/tokenize.pyc matches /Users/mpietre/Development/Library/buildout.python/parts/opt/lib/python2.7/tokenize.py
import tokenize # precompiled from /Users/mpietre/Development/Library/buildout.python/parts/opt/lib/python2.7/tokenize.pyc
dlopen("/Users/mpieters/Development/venvs/stackoverflow-2.7/lib/python2.7/lib-dynload/itertools.so", 2);
import itertools # dynamically loaded from /Users/mpieters/Development/venvs/stackoverflow-2.7/lib/python2.7/lib-dynload/itertools.so
# /Users/mpietre/Development/Library/buildout.python/parts/opt/lib/python2.7/token.pyc matches /Users/mpietre/Development/Library/buildout.python/parts/opt/lib/python2.7/token.py
import token # precompiled from /Users/mpietre/Development/Library/buildout.python/parts/opt/lib/python2.7/token.pyc
dlopen("/Users/mpieters/Development/venvs/stackoverflow-2.7/lib/python2.7/lib-dynload/operator.so", 2);
import operator # dynamically loaded from /Users/mpieters/Development/venvs/stackoverflow-2.7/lib/python2.7/lib-dynload/operator.so
# /Users/mpietre/Development/Library/buildout.python/parts/opt/lib/python2.7/collections.pyc matches /Users/mpietre/Development/Library/buildout.python/parts/opt/lib/python2.7/collections.py
import collections # precompiled from /Users/mpietre/Development/Library/buildout.python/parts/opt/lib/python2.7/collections.pyc
dlopen("/Users/mpieters/Development/venvs/stackoverflow-2.7/lib/python2.7/lib-dynload/_collections.so", 2);
import _collections # dynamically loaded from /Users/mpieters/Development/venvs/stackoverflow-2.7/lib/python2.7/lib-dynload/_collections.so
# /Users/mpietre/Development/Library/buildout.python/parts/opt/lib/python2.7/keyword.pyc matches /Users/mpietre/Development/Library/buildout.python/parts/opt/lib/python2.7/keyword.py
import keyword # precompiled from /Users/mpietre/Development/Library/buildout.python/parts/opt/lib/python2.7/keyword.pyc
# /Users/mpietre/Development/Library/buildout.python/parts/opt/lib/python2.7/heapq.pyc matches /Users/mpietre/Development/Library/buildout.python/parts/opt/lib/python2.7/heapq.py
import heapq # precompiled from /Users/mpietre/Development/Library/buildout.python/parts/opt/lib/python2.7/heapq.pyc
dlopen("/Users/mpieters/Development/venvs/stackoverflow-2.7/lib/python2.7/lib-dynload/_heapq.so", 2);
import _heapq # dynamically loaded from /Users/mpieters/Development/venvs/stackoverflow-2.7/lib/python2.7/lib-dynload/_heapq.so
import thread # builtin
# /Users/mpietre/Development/Library/buildout.python/parts/opt/lib/python2.7/repr.pyc matches /Users/mpietre/Development/Library/buildout.python/parts/opt/lib/python2.7/repr.py
import repr # precompiled from /Users/mpietre/Development/Library/buildout.python/parts/opt/lib/python2.7/repr.pyc
# /Users/mpietre/Development/Library/buildout.python/parts/opt/lib/python2.7/traceback.pyc matches /Users/mpietre/Development/Library/buildout.python/parts/opt/lib/python2.7/traceback.py
import traceback # precompiled from /Users/mpietre/Development/Library/buildout.python/parts/opt/lib/python2.7/traceback.pyc
# /Users/mpieters/Development/venvs/stackoverflow-2.7/lib/python2.7/locale.pyc matches /Users/mpieters/Development/venvs/stackoverflow-2.7/lib/python2.7/locale.py
import locale # precompiled from /Users/mpieters/Development/venvs/stackoverflow-2.7/lib/python2.7/locale.pyc
# /Users/mpietre/Development/Library/buildout.python/parts/opt/lib/python2.7/functools.pyc matches /Users/mpietre/Development/Library/buildout.python/parts/opt/lib/python2.7/functools.py
import functools # precompiled from /Users/mpietre/Development/Library/buildout.python/parts/opt/lib/python2.7/functools.pyc
dlopen("/Users/mpieters/Development/venvs/stackoverflow-2.7/lib/python2.7/lib-dynload/_functools.so", 2);
import _functools # dynamically loaded from /Users/mpieters/Development/venvs/stackoverflow-2.7/lib/python2.7/lib-dynload/_functools.so
# /Users/mpietre/Development/Library/buildout.python/parts/opt/lib/python2.7/getopt.pyc matches /Users/mpietre/Development/Library/buildout.python/parts/opt/lib/python2.7/getopt.py
import getopt # precompiled from /Users/mpietre/Development/Library/buildout.python/parts/opt/lib/python2.7/getopt.pyc
pydoc - the Python documentation tool

pydoc.py  ...
    Show text documentation on something.   may be the name of a
    Python keyword, topic, function, module, or package, or a dotted
    reference to a class or function within a module or module in a
    package.  If  contains a '/', it is used as the path to a
    Python source file to document. If name is 'keywords', 'topics',
    or 'modules', a listing of these things is displayed.

pydoc.py -k 
    Search for a keyword in the synopsis lines of all available modules.

pydoc.py -p 
    Start an HTTP server on the given port on the local machine.

pydoc.py -g
    Pop up a graphical interface for finding and serving documentation.

pydoc.py -w  ...
    Write out the HTML documentation for a module to a file in the current
    directory.  If  contains a '/', it is treated as a filename; if
    it names a directory, documentation is written for all the contents.

# clear __builtin__._
# clear sys.path
# clear sys.argv
# clear sys.ps1
# clear sys.ps2
# clear sys.exitfunc
# clear sys.exc_type
# clear sys.exc_value
# clear sys.exc_traceback
# clear sys.last_type
# clear sys.last_value
# clear sys.last_traceback
# clear sys.path_hooks
# clear sys.path_importer_cache
# clear sys.meta_path
# clear sys.flags
# clear sys.float_info
# restore sys.stdin
# restore sys.stdout
# restore sys.stderr
# cleanup __main__
# cleanup[1] _collections
# cleanup[1] locale
# cleanup[1] functools
# cleanup[1] encodings
# cleanup[1] site
# cleanup[1] runpy
# cleanup[1] operator
# cleanup[1] supervisor
# cleanup[1] _heapq
# cleanup[1] abc
# cleanup[1] _weakrefset
# cleanup[1] sre_constants
# cleanup[1] collections
# cleanup[1] _codecs
# cleanup[1] opcode
# cleanup[1] _warnings
# cleanup[1] mpl_toolkits
# cleanup[1] inspect
# cleanup[1] encodings.utf_8
# cleanup[1] repr
# cleanup[1] codecs
# cleanup[1] getopt
# cleanup[1] pkgutil
# cleanup[1] _functools
# cleanup[1] thread
# cleanup[1] keyword
# cleanup[1] strop
# cleanup[1] signal
# cleanup[1] traceback
# cleanup[1] itertools
# cleanup[1] posix
# cleanup[1] encodings.aliases
# cleanup[1] exceptions
# cleanup[1] _weakref
# cleanup[1] token
# cleanup[1] dis
# cleanup[1] tokenize
# cleanup[1] heapq
# cleanup[1] string
# cleanup[1] imp
# cleanup[1] zipimport
# cleanup[1] re
# cleanup[1] _locale
# cleanup[1] sre_compile
# cleanup[1] _sre
# cleanup[1] sre_parse
# cleanup[2] copy_reg
# cleanup[2] posixpath
# cleanup[2] errno
# cleanup[2] _abcoll
# cleanup[2] types
# cleanup[2] genericpath
# cleanup[2] stat
# cleanup[2] warnings
# cleanup[2] UserDict
# cleanup[2] os.path
# cleanup[2] linecache
# cleanup[2] os
# cleanup sys
# cleanup __builtin__
# cleanup ints: 21 unfreed ints
# cleanup floats

Đó là 53 nhập khẩu:

$ bin/python -v -m pydoc -h 2>&1 | egrep ^import | wc -l
      53

Thay vì tải tệp nguồn (lớn hơn) mỗi lần và biên dịch nó, một tệp byte nhỏ hơn có thể được đọc và sử dụng ngay lập tức. Điều đó dễ dàng thêm tối đa 1/3 hoặc 1/2 một giây chỉ để in một số thông tin trợ giúp cho một công cụ dòng lệnh.

Python không tạo tệp bộ đệm cho tập lệnh chính; Đó là bởi vì điều đó sẽ làm lộn xộn thư mục tập lệnh của bạn với các tệp sẽ không được tải gần như thường xuyên khi các mô -đun được tải.

Nếu bạn chạy một tập lệnh thường xuyên thời gian biên dịch cho một tệp đó ảnh hưởng đến bạn, bạn luôn có thể di chuyển phần lớn mã sang một mô -đun (và tránh phải biên dịch một tập lệnh lớn) hoặc bạn có thể sử dụng công cụ compileall để tạo Tệp bộ đệm .pyc cho tập lệnh, sau đó chạy tệp .pyc trực tiếp đó. Lưu ý rằng Python sau đó sẽ không biên dịch lại tệp đó nếu bạn thay đổi tập lệnh!

Tệp .pyc là gì?

Sự khác biệt giữa các tệp PY và .pyc là gì?

Tại sao tệp .pyc không được tạo?

Tôi có thể xóa các tệp .pyc không?