Decrease the time required to import astroid #1320
Description
Steps to reproduce
python3 -X importtime -c 'import astroid'
Current behavior
It takes a half second to import astroid. This account for 92% of pylint's startup time in 2.13.0-dev0. See pylint-dev/pylint#4814 for details.
import time: self [us] | cumulative | imported package
import time: 182 | 182 | _io
import time: 59 | 59 | marshal
import time: 213 | 213 | posix
import time: 463 | 916 | _frozen_importlib_external
import time: 143 | 143 | time
import time: 210 | 353 | zipimport
import time: 68 | 68 | _codecs
import time: 8157 | 8225 | codecs
import time: 4532 | 4532 | encodings.aliases
import time: 2092 | 14848 | encodings
import time: 526 | 526 | encodings.utf_8
import time: 183 | 183 | _signal
import time: 910 | 910 | encodings.latin_1
import time: 34 | 34 | _abc
import time: 527 | 560 | abc
import time: 539 | 1099 | io
import time: 43 | 43 | _stat
import time: 522 | 564 | stat
import time: 1066 | 1066 | _collections_abc
import time: 459 | 459 | genericpath
import time: 481 | 939 | posixpath
import time: 781 | 3349 | os
import time: 451 | 451 | _sitebuiltins
import time: 57 | 57 | _locale
import time: 411 | 467 | _bootlocale
import time: 1220 | 1220 | apport_python_hook
import time: 396 | 1615 | sitecustomize
import time: 4927 | 10808 | site
import time: 989 | 989 | types
import time: 833 | 833 | warnings
import time: 1833 | 3654 | importlib
import time: 954 | 954 | enum
import time: 58 | 58 | _sre
import time: 560 | 560 | sre_constants
import time: 1033 | 1593 | sre_parse
import time: 788 | 2437 | sre_compile
import time: 58 | 58 | _operator
import time: 1129 | 1187 | operator
import time: 424 | 424 | keyword
import time: 34 | 34 | _heapq
import time: 499 | 533 | heapq
import time: 85 | 85 | itertools
import time: 496 | 496 | reprlib
import time: 47 | 47 | _collections
import time: 1360 | 4129 | collections
import time: 37 | 37 | _functools
import time: 3949 | 8114 | functools
import time: 451 | 451 | copyreg
import time: 751 | 12704 | re
import time: 547 | 13251 | fnmatch
import time: 70 | 70 | nt
import time: 49 | 49 | nt
import time: 46 | 46 | nt
import time: 46 | 46 | nt
import time: 608 | 817 | ntpath
import time: 47 | 47 | errno
import time: 734 | 734 | urllib
import time: 1519 | 2253 | urllib.parse
import time: 3700 | 20066 | pathlib
import time: 1277 | 1277 | astroid.__pkginfo__
import time: 423 | 423 | collections.abc
import time: 704 | 704 | contextlib
import time: 1683 | 2809 | typing
import time: 127 | 127 | _opcode
import time: 619 | 745 | opcode
import time: 744 | 1488 | dis
import time: 442 | 442 | importlib.machinery
import time: 480 | 480 | token
import time: 1048 | 1527 | tokenize
import time: 389 | 1915 | linecache
import time: 1941 | 5784 | inspect
import time: 518 | 518 | _weakrefset
import time: 873 | 1390 | weakref
import time: 1384 | 1384 | wrapt._wrappers
import time: 6921 | 9695 | wrapt.wrappers
import time: 1350 | 1350 | threading
import time: 1461 | 2811 | wrapt.decorators
import time: 1089 | 1089 | wrapt.importer
import time: 2134 | 15727 | wrapt
import time: 77 | 77 | copy_reg
import time: 449 | 449 | lazy_object_proxy.utils_py3
import time: 550 | 999 | lazy_object_proxy.utils
import time: 1466 | 1466 | lazy_object_proxy.cext
import time: 572 | 572 | lazy_object_proxy._version
import time: 4391 | 7503 | lazy_object_proxy
import time: 687 | 8190 | astroid.util
import time: 635 | 635 | pprint
import time: 2008 | 2643 | astroid.context
import time: 1714 | 1714 | astroid.exceptions
import time: 7641 | 7641 | typing_extensions
import time: 616 | 42312 | astroid.decorators
import time: 594 | 594 | astroid.mixins
import time: 1371 | 1371 | astroid.const
import time: 1881 | 1881 | astroid.interpreter._import
import time: 1275 | 1275 | distutils
import time: 385 | 385 | __future__
import time: 68 | 68 | binascii
import time: 631 | 631 | importlib.abc
import time: 503 | 1133 | importlib.util
import time: 66 | 66 | zlib
import time: 367 | 367 | _compression
import time: 251 | 251 | _bz2
import time: 485 | 1103 | bz2
import time: 217 | 217 | _lzma
import time: 431 | 647 | lzma
import time: 36 | 36 | pwd
import time: 26 | 26 | grp
import time: 1033 | 2908 | shutil
import time: 66 | 66 | _struct
import time: 337 | 402 | struct
import time: 1019 | 5528 | zipfile
import time: 599 | 599 | pkgutil
import time: 1913 | 1913 | platform
import time: 53 | 53 | math
import time: 120 | 120 | _datetime
import time: 1114 | 1286 | datetime
import time: 1129 | 1129 | xml
import time: 1078 | 2206 | xml.parsers
import time: 107 | 107 | pyexpat
import time: 431 | 2744 | xml.parsers.expat
import time: 1234 | 5263 | plistlib
import time: 578 | 578 | email
import time: 674 | 674 | email.errors
import time: 36 | 36 | _string
import time: 843 | 878 | string
import time: 465 | 1343 | email.quoprimime
import time: 524 | 524 | base64
import time: 402 | 925 | email.base64mime
import time: 451 | 451 | quopri
import time: 418 | 869 | email.encoders
import time: 874 | 1743 | email.charset
import time: 950 | 4960 | email.header
import time: 34 | 34 | _bisect
import time: 424 | 457 | bisect
import time: 27 | 27 | _sha512
import time: 22 | 22 | _random
import time: 616 | 1122 | random
import time: 136 | 136 | _socket
import time: 617 | 617 | select
import time: 885 | 1501 | selectors
import time: 1593 | 3229 | socket
import time: 1011 | 1011 | locale
import time: 919 | 1929 | calendar
import time: 557 | 2485 | email._parseaddr
import time: 813 | 7647 | email.utils
import time: 561 | 13167 | email._policybase
import time: 945 | 14785 | email.feedparser
import time: 8210 | 23572 | email.parser
import time: 721 | 721 | tempfile
import time: 1194 | 1194 | textwrap
import time: 6297 | 6297 | pkg_resources.extern
import time: 1130 | 1130 | pkg_resources._vendor
import time: 1168 | 2297 | pkg_resources._vendor.six
import time: 149 | 2446 | pkg_resources.extern.six
import time: 560 | 560 | pkg_resources._vendor.six
import time: 70 | 629 | pkg_resources._vendor.six.moves
import time: 56 | 685 | pkg_resources.extern.six.moves
import time: 20 | 20 | pkg_resources._vendor.six.moves
import time: 50 | 69 | pkg_resources._vendor.six.moves.urllib
import time: 461 | 461 | pkg_resources.py31compat
import time: 910 | 910 | pkg_resources._vendor.appdirs
import time: 81 | 990 | pkg_resources.extern.appdirs
import time: 436 | 436 | pkg_resources._vendor.packaging.__about__
import time: 3589 | 4025 | pkg_resources._vendor.packaging
import time: 72 | 4097 | pkg_resources.extern.packaging
import time: 378 | 378 | pkg_resources.extern.packaging._structures
import time: 2111 | 2489 | pkg_resources.extern.packaging.version
import time: 379 | 379 | pkg_resources.extern.packaging._compat
import time: 6610 | 6989 | pkg_resources.extern.packaging.specifiers
import time: 74 | 74 | org
import time: 17 | 90 | org.python
import time: 13 | 103 | org.python.core
import time: 539 | 641 | copy
import time: 1431 | 1431 | traceback
import time: 27210 | 29281 | pkg_resources._vendor.pyparsing
import time: 107 | 29388 | pkg_resources.extern.pyparsing
import time: 42 | 42 | pkg_resources.extern.six.moves.urllib
import time: 1463 | 1463 | pkg_resources.extern.packaging.markers
import time: 8461 | 39353 | pkg_resources.extern.packaging.requirements
import time: 4606 | 4606 | sysconfig
import time: 52302 | 159948 | pkg_resources
import time: 338 | 160286 | astroid.interpreter._import.util
import time: 1009 | 162569 | astroid.interpreter._import.spec
import time: 614 | 614 | distutils.errors
import time: 426 | 426 | distutils.dep_util
import time: 355 | 355 | distutils.debug
import time: 504 | 504 | distutils.log
import time: 548 | 1406 | distutils.spawn
import time: 559 | 2391 | distutils.util
import time: 889 | 3280 | distutils.sysconfig
import time: 854 | 4746 | astroid.modutils
import time: 463 | 463 | astroid.transforms
import time: 3030 | 172688 | astroid.manager
import time: 4830 | 178888 | astroid.bases
import time: 8974 | 8974 | astroid.nodes.const
import time: 737 | 737 | astroid.nodes.as_string
import time: 1306 | 2042 | astroid.nodes.node_ng
import time: 5136 | 240752 | astroid.nodes.node_classes
import time: 467 | 467 | astroid.interpreter.dunder_lookup
import time: 1416 | 1883 | astroid.nodes.scoped_nodes
import time: 4791 | 247424 | astroid.nodes
import time: 57 | 57 | _ast
import time: 764 | 820 | ast
import time: 177912 | 177912 | astroid.raw_building
import time: 656 | 178567 | astroid.helpers
import time: 569 | 569 | astroid.arguments
import time: 972 | 1541 | astroid.protocols
import time: 1415 | 182342 | astroid.inference
import time: 1575 | 1575 | astroid.astroid_manager
import time: 1293 | 1293 | astroid.brain
import time: 712 | 2005 | astroid.brain.helpers
import time: 76 | 76 | typed_ast
import time: 53 | 128 | typed_ast.ast3
import time: 655 | 783 | astroid._ast
import time: 1616 | 2399 | astroid.rebuilder
import time: 561 | 2959 | astroid.builder
import time: 355 | 355 | astroid.inference_tip
import time: 701 | 701 | astroid.objects
import time: 305 | 305 | astroid.brain.brain_numpy_utils
import time: 46840 | 509498 | astroid
Expected behavior
Faster import, so pylint's can analyses empty file in less than half a second.