From 2d08badbd8c285c073d9cb200e1533cabccf94eb Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Anders=20Hovm=C3=B6ller?= <anders.hovmoller@trioptima.com>
Date: Mon, 18 Mar 2019 14:38:33 +0100
Subject: [PATCH] First stab at reducing startup time

---
 src/pip/_internal/__init__.py               |  8 +-
 src/pip/_internal/cli/autocompletion.py     |  1 -
 src/pip/_internal/cli/base_command.py       | 83 +++++++++++++--------
 src/pip/_internal/cli/main_parser.py        | 26 ++++---
 src/pip/_internal/commands/check.py         |  6 +-
 src/pip/_internal/commands/completion.py    |  3 +-
 src/pip/_internal/commands/configuration.py | 21 ++++--
 src/pip/_internal/commands/download.py      | 19 +++--
 src/pip/_internal/commands/freeze.py        |  9 ++-
 src/pip/_internal/commands/hash.py          |  9 ++-
 src/pip/_internal/commands/help.py          |  4 +-
 src/pip/_internal/commands/install.py       | 68 ++++++++++-------
 src/pip/_internal/commands/list.py          | 31 +++++---
 src/pip/_internal/commands/search.py        | 35 +++++----
 src/pip/_internal/commands/show.py          | 18 +++--
 src/pip/_internal/commands/uninstall.py     | 13 ++--
 src/pip/_internal/commands/wheel.py         | 26 ++++---
 src/pip/_internal/exceptions.py             |  3 +-
 src/pip/_internal/utils/deprecation.py      |  4 +-
 src/pip/_internal/utils/misc.py             | 16 +---
 src/pip/_internal/utils/misc_fast_import.py | 15 ++++
 tests/functional/test_help.py               |  2 +-
 tests/unit/test_utils.py                    |  3 +-
 23 files changed, 257 insertions(+), 166 deletions(-)
 create mode 100644 src/pip/_internal/utils/misc_fast_import.py

diff --git a/src/pip/_internal/__init__.py b/src/pip/_internal/__init__.py
index 9c1637cfc11..52ddeca1ef6 100755
--- a/src/pip/_internal/__init__.py
+++ b/src/pip/_internal/__init__.py
@@ -37,14 +37,13 @@
         else:
             securetransport.inject_into_urllib3()
 
-from pip._internal.cli.autocompletion import autocomplete
 from pip._internal.cli.main_parser import parse_command
 from pip._internal.commands import commands_dict
 from pip._internal.exceptions import PipError
 from pip._internal.utils import deprecation
+
 from pip._internal.vcs import git, mercurial, subversion, bazaar  # noqa
 from pip._vendor.urllib3.exceptions import InsecureRequestWarning
-
 logger = logging.getLogger(__name__)
 
 # Hide the InsecureRequestWarning from urllib3
@@ -58,7 +57,10 @@ def main(args=None):
     # Configure our deprecation warnings to be sent through loggers
     deprecation.install_warning_logger()
 
-    autocomplete()
+    if 'PIP_AUTO_COMPLETE' in os.environ:
+        from pip._internal.cli.autocompletion import autocomplete
+        autocomplete()
+        return 1
 
     try:
         cmd_name, cmd_args = parse_command(args)
diff --git a/src/pip/_internal/cli/autocompletion.py b/src/pip/_internal/cli/autocompletion.py
index 0a04199e6dc..7131eacb4a1 100644
--- a/src/pip/_internal/cli/autocompletion.py
+++ b/src/pip/_internal/cli/autocompletion.py
@@ -98,7 +98,6 @@ def autocomplete():
                 subcommands = auto_complete_paths(current, completion_type)
 
         print(' '.join([x for x in subcommands if x.startswith(current)]))
-    sys.exit(1)
 
 
 def get_path_completion_type(cwords, cword, opts):
diff --git a/src/pip/_internal/cli/base_command.py b/src/pip/_internal/cli/base_command.py
index f6108c96eb5..5385e01de27 100644
--- a/src/pip/_internal/cli/base_command.py
+++ b/src/pip/_internal/cli/base_command.py
@@ -2,38 +2,7 @@
 from __future__ import absolute_import, print_function
 
 import logging
-import logging.config
-import optparse
-import os
-import platform
-import sys
-import traceback
-
-from pip._internal.cli import cmdoptions
-from pip._internal.cli.parser import (
-    ConfigOptionParser, UpdatingDefaultsHelpFormatter,
-)
-from pip._internal.cli.status_codes import (
-    ERROR, PREVIOUS_BUILD_DIR_ERROR, SUCCESS, UNKNOWN_ERROR,
-    VIRTUALENV_NOT_FOUND,
-)
-from pip._internal.download import PipSession
-from pip._internal.exceptions import (
-    BadCommand, CommandError, InstallationError, PreviousBuildDirError,
-    UninstallationError,
-)
-from pip._internal.index import PackageFinder
-from pip._internal.locations import running_under_virtualenv
-from pip._internal.req.constructors import (
-    install_req_from_editable, install_req_from_line,
-)
-from pip._internal.req.req_file import parse_requirements
-from pip._internal.utils.deprecation import deprecated
-from pip._internal.utils.logging import BrokenStdoutLoggingError, setup_logging
-from pip._internal.utils.misc import (
-    get_prog, normalize_path, redact_password_from_url,
-)
-from pip._internal.utils.outdated import pip_version_check
+
 from pip._internal.utils.typing import MYPY_CHECK_RUNNING
 
 if MYPY_CHECK_RUNNING:
@@ -54,6 +23,15 @@ class Command(object):
 
     def __init__(self, isolated=False):
         # type: (bool) -> None
+
+        import optparse
+
+        from pip._internal.cli import cmdoptions
+        from pip._internal.cli.parser import (
+            ConfigOptionParser, UpdatingDefaultsHelpFormatter,
+        )
+        from pip._internal.utils.misc_fast_import import get_prog
+
         parser_kw = {
             'usage': self.usage,
             'prog': '%s %s' % (get_prog(), self.name),
@@ -83,6 +61,12 @@ def run(self, options, args):
 
     def _build_session(self, options, retries=None, timeout=None):
         # type: (Values, Optional[int], Optional[int]) -> PipSession
+        import os
+
+        from pip._internal.download import PipSession
+        from pip._internal.utils.misc import (
+            normalize_path, )
+
         session = PipSession(
             cache=(
                 normalize_path(os.path.join(options.cache_dir, "http"))
@@ -125,6 +109,25 @@ def parse_args(self, args):
 
     def main(self, args):
         # type: (List[str]) -> int
+        import logging.config
+        import os
+        import platform
+        import sys
+        import traceback
+
+        from pip._internal.cli.status_codes import (
+            ERROR, PREVIOUS_BUILD_DIR_ERROR, SUCCESS, UNKNOWN_ERROR,
+            VIRTUALENV_NOT_FOUND,
+        )
+        from pip._internal.exceptions import (
+            BadCommand, CommandError, InstallationError, PreviousBuildDirError,
+            UninstallationError,
+        )
+        from pip._internal.locations import running_under_virtualenv
+        from pip._internal.utils.deprecation import deprecated
+        from pip._internal.utils.logging import BrokenStdoutLoggingError, setup_logging
+        from pip._internal.utils.outdated import pip_version_check
+
         options, args = self.parse_args(args)
 
         # Set verbosity so that it can be used elsewhere.
@@ -253,6 +256,15 @@ def populate_requirement_set(requirement_set,  # type: RequirementSet
         # NOTE: As a side-effect, options.require_hashes and
         #       requirement_set.require_hashes may be updated
 
+        from pip._internal.download import PipSession
+        from pip._internal.exceptions import (
+            CommandError, )
+        from pip._internal.index import PackageFinder
+        from pip._internal.req.constructors import (
+            install_req_from_editable, install_req_from_line,
+        )
+        from pip._internal.req.req_file import parse_requirements
+
         for filename in options.constraints:
             for req_to_add in parse_requirements(
                     filename,
@@ -314,6 +326,13 @@ def _build_package_finder(
         implementation=None    # type: Optional[str]
     ):
         # type: (...) -> PackageFinder
+
+        from pip._internal.download import PipSession
+        from pip._internal.index import PackageFinder
+        from pip._internal.utils.misc import (
+            redact_password_from_url,
+        )
+
         """
         Create a package finder appropriate to this requirement command.
         """
diff --git a/src/pip/_internal/cli/main_parser.py b/src/pip/_internal/cli/main_parser.py
index 767f35d50ee..11c24cac94d 100644
--- a/src/pip/_internal/cli/main_parser.py
+++ b/src/pip/_internal/cli/main_parser.py
@@ -4,18 +4,7 @@
 import os
 import sys
 
-from pip import __version__
-from pip._internal.cli import cmdoptions
-from pip._internal.cli.parser import (
-    ConfigOptionParser, UpdatingDefaultsHelpFormatter,
-)
-from pip._internal.commands import (
-    commands_dict, get_similar_commands, get_summaries,
-)
-from pip._internal.exceptions import CommandError
-from pip._internal.utils.misc import get_prog
 from pip._internal.utils.typing import MYPY_CHECK_RUNNING
-
 if MYPY_CHECK_RUNNING:
     from typing import Tuple, List
 
@@ -28,6 +17,16 @@ def create_main_parser():
     """Creates and returns the main parser for pip's CLI
     """
 
+    from pip import __version__
+    from pip._internal.cli import cmdoptions
+    from pip._internal.cli.parser import (
+        ConfigOptionParser, UpdatingDefaultsHelpFormatter,
+    )
+    from pip._internal.commands import (
+        get_summaries,
+    )
+    from pip._internal.utils.misc_fast_import import get_prog
+
     parser_kw = {
         'usage': '\n%prog <command> [options]',
         'add_help_option': False,
@@ -63,6 +62,11 @@ def create_main_parser():
 
 def parse_command(args):
     # type: (List[str]) -> Tuple[str, List[str]]
+    from pip._internal.commands import (
+        commands_dict, get_similar_commands,
+    )
+    from pip._internal.exceptions import CommandError
+
     parser = create_main_parser()
 
     # Note: parser calls disable_interspersed_args(), so the result of this
diff --git a/src/pip/_internal/commands/check.py b/src/pip/_internal/commands/check.py
index 801cecc0b84..1cf1b8527fa 100644
--- a/src/pip/_internal/commands/check.py
+++ b/src/pip/_internal/commands/check.py
@@ -1,9 +1,6 @@
 import logging
 
 from pip._internal.cli.base_command import Command
-from pip._internal.operations.check import (
-    check_package_set, create_package_set_from_installed,
-)
 
 logger = logging.getLogger(__name__)
 
@@ -16,6 +13,9 @@ class CheckCommand(Command):
     summary = 'Verify installed packages have compatible dependencies.'
 
     def run(self, options, args):
+        from pip._internal.operations.check import (
+            check_package_set, create_package_set_from_installed,
+        )
         package_set, parsing_probs = create_package_set_from_installed()
         missing, conflicting = check_package_set(package_set)
 
diff --git a/src/pip/_internal/commands/completion.py b/src/pip/_internal/commands/completion.py
index 2fcdd393ed6..795cc2beb1f 100644
--- a/src/pip/_internal/commands/completion.py
+++ b/src/pip/_internal/commands/completion.py
@@ -4,7 +4,8 @@
 import textwrap
 
 from pip._internal.cli.base_command import Command
-from pip._internal.utils.misc import get_prog
+from pip._internal.utils.misc_fast_import import get_prog
+
 
 BASE_COMPLETION = """
 # pip %(shell)s completion start%(script)s# pip %(shell)s completion end
diff --git a/src/pip/_internal/commands/configuration.py b/src/pip/_internal/commands/configuration.py
index 950e2057368..eb8315c7c3f 100644
--- a/src/pip/_internal/commands/configuration.py
+++ b/src/pip/_internal/commands/configuration.py
@@ -3,12 +3,7 @@
 import subprocess
 
 from pip._internal.cli.base_command import Command
-from pip._internal.cli.status_codes import ERROR, SUCCESS
-from pip._internal.configuration import Configuration, kinds
-from pip._internal.exceptions import PipError
-from pip._internal.locations import running_under_virtualenv, site_config_file
-from pip._internal.utils.deprecation import deprecated
-from pip._internal.utils.misc import get_prog
+from pip._internal.utils.misc_fast_import import get_prog
 
 logger = logging.getLogger(__name__)
 
@@ -96,6 +91,10 @@ def __init__(self, *args, **kwargs):
         self.parser.insert_option_group(0, self.cmd_opts)
 
     def run(self, options, args):
+        from pip._internal.cli.status_codes import ERROR, SUCCESS
+        from pip._internal.configuration import Configuration
+        from pip._internal.exceptions import PipError
+
         handlers = {
             "list": self.list_values,
             "edit": self.open_in_editor,
@@ -139,6 +138,11 @@ def run(self, options, args):
         return SUCCESS
 
     def _determine_file(self, options, need_value):
+        from pip._internal.configuration import kinds
+        from pip._internal.exceptions import PipError
+        from pip._internal.locations import running_under_virtualenv, site_config_file
+        from pip._internal.utils.deprecation import deprecated
+
         # Convert legacy venv_file option to site_file or error
         if options.venv_file and not options.site_file:
             if running_under_virtualenv():
@@ -201,6 +205,8 @@ def unset_name(self, options, args):
         self._save_configuration()
 
     def open_in_editor(self, options, args):
+        from pip._internal.exceptions import PipError
+
         editor = self._determine_editor(options)
 
         fname = self.configuration.get_file_to_edit()
@@ -218,6 +224,7 @@ def open_in_editor(self, options, args):
     def _get_n_args(self, args, example, n):
         """Helper to make sure the command got the right number of arguments
         """
+        from pip._internal.exceptions import PipError
         if len(args) != n:
             msg = (
                 'Got unexpected number of arguments, expected {}. '
@@ -231,6 +238,7 @@ def _get_n_args(self, args, example, n):
             return args
 
     def _save_configuration(self):
+        from pip._internal.exceptions import PipError
         # We successfully ran a modifying command. Need to save the
         # configuration.
         try:
@@ -243,6 +251,7 @@ def _save_configuration(self):
             raise PipError("Internal Error.")
 
     def _determine_editor(self, options):
+        from pip._internal.exceptions import PipError
         if options.editor is not None:
             return options.editor
         elif "VISUAL" in os.environ:
diff --git a/src/pip/_internal/commands/download.py b/src/pip/_internal/commands/download.py
index a57e4bc4cb8..99fa537842d 100644
--- a/src/pip/_internal/commands/download.py
+++ b/src/pip/_internal/commands/download.py
@@ -3,15 +3,7 @@
 import logging
 import os
 
-from pip._internal.cli import cmdoptions
 from pip._internal.cli.base_command import RequirementCommand
-from pip._internal.operations.prepare import RequirementPreparer
-from pip._internal.req import RequirementSet
-from pip._internal.req.req_tracker import RequirementTracker
-from pip._internal.resolve import Resolver
-from pip._internal.utils.filesystem import check_path_owner
-from pip._internal.utils.misc import ensure_dir, normalize_path
-from pip._internal.utils.temp_dir import TempDirectory
 
 logger = logging.getLogger(__name__)
 
@@ -42,6 +34,8 @@ class DownloadCommand(RequirementCommand):
     def __init__(self, *args, **kw):
         super(DownloadCommand, self).__init__(*args, **kw)
 
+        from pip._internal.cli import cmdoptions
+
         cmd_opts = self.cmd_opts
 
         cmd_opts.add_option(cmdoptions.constraints())
@@ -83,6 +77,15 @@ def __init__(self, *args, **kw):
         self.parser.insert_option_group(0, cmd_opts)
 
     def run(self, options, args):
+        from pip._internal.cli import cmdoptions
+        from pip._internal.operations.prepare import RequirementPreparer
+        from pip._internal.req import RequirementSet
+        from pip._internal.req.req_tracker import RequirementTracker
+        from pip._internal.resolve import Resolver
+        from pip._internal.utils.filesystem import check_path_owner
+        from pip._internal.utils.misc import ensure_dir, normalize_path
+        from pip._internal.utils.temp_dir import TempDirectory
+
         options.ignore_installed = True
         # editable doesn't really make sense for `pip download`, but the bowels
         # of the RequirementSet code require that property.
diff --git a/src/pip/_internal/commands/freeze.py b/src/pip/_internal/commands/freeze.py
index dc9c53a6b5d..5befc584e51 100644
--- a/src/pip/_internal/commands/freeze.py
+++ b/src/pip/_internal/commands/freeze.py
@@ -2,11 +2,7 @@
 
 import sys
 
-from pip._internal.cache import WheelCache
 from pip._internal.cli.base_command import Command
-from pip._internal.models.format_control import FormatControl
-from pip._internal.operations.freeze import freeze
-from pip._internal.utils.compat import stdlib_pkgs
 
 DEV_PKGS = {'pip', 'setuptools', 'distribute', 'wheel'}
 
@@ -71,6 +67,11 @@ def __init__(self, *args, **kw):
         self.parser.insert_option_group(0, self.cmd_opts)
 
     def run(self, options, args):
+        from pip._internal.cache import WheelCache
+        from pip._internal.models.format_control import FormatControl
+        from pip._internal.operations.freeze import freeze
+        from pip._internal.utils.compat import stdlib_pkgs
+
         format_control = FormatControl(set(), set())
         wheel_cache = WheelCache(options.cache_dir, format_control)
         skip = set(stdlib_pkgs)
diff --git a/src/pip/_internal/commands/hash.py b/src/pip/_internal/commands/hash.py
index 423440e9c29..c30fe865971 100644
--- a/src/pip/_internal/commands/hash.py
+++ b/src/pip/_internal/commands/hash.py
@@ -5,9 +5,6 @@
 import sys
 
 from pip._internal.cli.base_command import Command
-from pip._internal.cli.status_codes import ERROR
-from pip._internal.utils.hashes import FAVORITE_HASH, STRONG_HASHES
-from pip._internal.utils.misc import read_chunks
 
 logger = logging.getLogger(__name__)
 
@@ -27,6 +24,8 @@ class HashCommand(Command):
 
     def __init__(self, *args, **kw):
         super(HashCommand, self).__init__(*args, **kw)
+
+        from pip._internal.utils.hashes import FAVORITE_HASH, STRONG_HASHES
         self.cmd_opts.add_option(
             '-a', '--algorithm',
             dest='algorithm',
@@ -38,6 +37,8 @@ def __init__(self, *args, **kw):
         self.parser.insert_option_group(0, self.cmd_opts)
 
     def run(self, options, args):
+        from pip._internal.cli.status_codes import ERROR
+
         if not args:
             self.parser.print_usage(sys.stderr)
             return ERROR
@@ -50,6 +51,8 @@ def run(self, options, args):
 
 def _hash_of_file(path, algorithm):
     """Return the hash digest of a file."""
+    from pip._internal.utils.misc import read_chunks
+
     with open(path, 'rb') as archive:
         hash = hashlib.new(algorithm)
         for chunk in read_chunks(archive):
diff --git a/src/pip/_internal/commands/help.py b/src/pip/_internal/commands/help.py
index 49a81cbb074..05a8a6838f2 100644
--- a/src/pip/_internal/commands/help.py
+++ b/src/pip/_internal/commands/help.py
@@ -1,8 +1,6 @@
 from __future__ import absolute_import
 
 from pip._internal.cli.base_command import Command
-from pip._internal.cli.status_codes import SUCCESS
-from pip._internal.exceptions import CommandError
 
 
 class HelpCommand(Command):
@@ -15,6 +13,8 @@ class HelpCommand(Command):
 
     def run(self, options, args):
         from pip._internal.commands import commands_dict, get_similar_commands
+        from pip._internal.cli.status_codes import SUCCESS
+        from pip._internal.exceptions import CommandError
 
         try:
             # 'pip help' with no args is handled by pip.__init__.parseopt()
diff --git a/src/pip/_internal/commands/install.py b/src/pip/_internal/commands/install.py
index c13da44c6c3..124394d9480 100644
--- a/src/pip/_internal/commands/install.py
+++ b/src/pip/_internal/commands/install.py
@@ -1,34 +1,8 @@
 from __future__ import absolute_import
 
-import errno
 import logging
-import operator
-import os
-import shutil
-from optparse import SUPPRESS_HELP
 
-from pip._vendor import pkg_resources
-
-from pip._internal.cache import WheelCache
-from pip._internal.cli import cmdoptions
 from pip._internal.cli.base_command import RequirementCommand
-from pip._internal.cli.status_codes import ERROR
-from pip._internal.exceptions import (
-    CommandError, InstallationError, PreviousBuildDirError,
-)
-from pip._internal.locations import distutils_scheme, virtualenv_no_global
-from pip._internal.operations.check import check_install_conflicts
-from pip._internal.operations.prepare import RequirementPreparer
-from pip._internal.req import RequirementSet, install_given_reqs
-from pip._internal.req.req_tracker import RequirementTracker
-from pip._internal.resolve import Resolver
-from pip._internal.utils.filesystem import check_path_owner
-from pip._internal.utils.misc import (
-    ensure_dir, get_installed_version,
-    protect_pip_from_modification_on_windows,
-)
-from pip._internal.utils.temp_dir import TempDirectory
-from pip._internal.wheel import WheelBuilder
 
 logger = logging.getLogger(__name__)
 
@@ -96,6 +70,10 @@ class InstallCommand(RequirementCommand):
     def __init__(self, *args, **kw):
         super(InstallCommand, self).__init__(*args, **kw)
 
+        from optparse import SUPPRESS_HELP
+
+        from pip._internal.cli import cmdoptions
+
         cmd_opts = self.cmd_opts
 
         cmd_opts.add_option(cmdoptions.requirements())
@@ -241,6 +219,30 @@ def __init__(self, *args, **kw):
         self.parser.insert_option_group(0, cmd_opts)
 
     def run(self, options, args):
+        import operator
+        import os
+
+        from pip._vendor import pkg_resources
+
+        from pip._internal.cache import WheelCache
+        from pip._internal.cli import cmdoptions
+        from pip._internal.cli.status_codes import ERROR
+        from pip._internal.exceptions import (
+            CommandError, InstallationError, PreviousBuildDirError,
+        )
+        from pip._internal.locations import virtualenv_no_global
+        from pip._internal.operations.prepare import RequirementPreparer
+        from pip._internal.req import RequirementSet, install_given_reqs
+        from pip._internal.req.req_tracker import RequirementTracker
+        from pip._internal.resolve import Resolver
+        from pip._internal.utils.filesystem import check_path_owner
+        from pip._internal.utils.misc import (
+            get_installed_version,
+            protect_pip_from_modification_on_windows,
+        )
+        from pip._internal.utils.temp_dir import TempDirectory
+        from pip._internal.wheel import WheelBuilder
+
         cmdoptions.check_install_build_global(options)
         upgrade_strategy = "to-satisfy-only"
         if options.upgrade:
@@ -464,6 +466,13 @@ def run(self, options, args):
         return requirement_set
 
     def _handle_target_dir(self, target_dir, target_temp_dir, upgrade):
+        import os
+        import shutil
+
+        from pip._internal.locations import distutils_scheme
+        from pip._internal.utils.misc import (
+            ensure_dir, )
+
         ensure_dir(target_dir)
 
         # Checking both purelib and platlib directories for installed
@@ -520,6 +529,9 @@ def _handle_target_dir(self, target_dir, target_temp_dir, upgrade):
                     )
 
     def _warn_about_conflicts(self, to_install):
+
+        from pip._internal.operations.check import check_install_conflicts
+
         try:
             package_set, _dep_info = check_install_conflicts(to_install)
         except Exception:
@@ -547,6 +559,8 @@ def _warn_about_conflicts(self, to_install):
 
 
 def get_lib_location_guesses(*args, **kwargs):
+    from pip._internal.locations import distutils_scheme
+
     scheme = distutils_scheme('', *args, **kwargs)
     return [scheme['purelib'], scheme['platlib']]
 
@@ -556,6 +570,8 @@ def create_env_error_message(error, show_traceback, using_user_site):
 
     It may occur anytime during the execution of the install command.
     """
+    import errno
+
     parts = []
 
     # Mention the error if we are not going to show a traceback
diff --git a/src/pip/_internal/commands/list.py b/src/pip/_internal/commands/list.py
index a6402749207..63af2460196 100644
--- a/src/pip/_internal/commands/list.py
+++ b/src/pip/_internal/commands/list.py
@@ -3,17 +3,7 @@
 import json
 import logging
 
-from pip._vendor import six
-from pip._vendor.six.moves import zip_longest
-
-from pip._internal.cli import cmdoptions
 from pip._internal.cli.base_command import Command
-from pip._internal.exceptions import CommandError
-from pip._internal.index import PackageFinder
-from pip._internal.utils.misc import (
-    dist_is_editable, get_installed_distributions,
-)
-from pip._internal.utils.packaging import get_installer
 
 logger = logging.getLogger(__name__)
 
@@ -32,6 +22,8 @@ class ListCommand(Command):
     def __init__(self, *args, **kw):
         super(ListCommand, self).__init__(*args, **kw)
 
+        from pip._internal.cli import cmdoptions
+
         cmd_opts = self.cmd_opts
 
         cmd_opts.add_option(
@@ -113,6 +105,8 @@ def _build_package_finder(self, options, index_urls, session):
         """
         Create a package finder appropriate to this list command.
         """
+
+        from pip._internal.index import PackageFinder
         return PackageFinder(
             find_links=options.find_links,
             index_urls=index_urls,
@@ -122,6 +116,12 @@ def _build_package_finder(self, options, index_urls, session):
         )
 
     def run(self, options, args):
+
+        from pip._internal.exceptions import CommandError
+        from pip._internal.utils.misc import (
+            get_installed_distributions,
+        )
+
         if options.outdated and options.uptodate:
             raise CommandError(
                 "Options --outdated and --uptodate cannot be combined.")
@@ -230,6 +230,8 @@ def output_package_listing_columns(self, data, header):
 
 
 def tabulate(vals):
+    from pip._vendor.six.moves import zip_longest
+
     # From pfmoore on GitHub:
     # https://github.com/pypa/pip/issues/3651#issuecomment-216932564
     assert len(vals) > 0
@@ -252,6 +254,11 @@ def format_for_columns(pkgs, options):
     Convert the package data into something usable
     by output_package_listing_columns.
     """
+
+    from pip._internal.utils.misc import (
+        dist_is_editable, )
+    from pip._internal.utils.packaging import get_installer
+
     running_outdated = options.outdated
     # Adjust the header for the `pip list --outdated` case.
     if running_outdated:
@@ -285,6 +292,10 @@ def format_for_columns(pkgs, options):
 
 
 def format_for_json(packages, options):
+    from pip._vendor import six
+
+    from pip._internal.utils.packaging import get_installer
+
     data = []
     for dist in packages:
         info = {
diff --git a/src/pip/_internal/commands/search.py b/src/pip/_internal/commands/search.py
index c157a3128a4..7ebc6dbf010 100644
--- a/src/pip/_internal/commands/search.py
+++ b/src/pip/_internal/commands/search.py
@@ -2,22 +2,12 @@
 
 import logging
 import sys
-import textwrap
-from collections import OrderedDict
-
-from pip._vendor import pkg_resources
-from pip._vendor.packaging.version import parse as parse_version
-# NOTE: XMLRPC Client is not annotated in typeshed as on 2017-07-17, which is
-#       why we ignore the type on this import
-from pip._vendor.six.moves import xmlrpc_client  # type: ignore
 
 from pip._internal.cli.base_command import Command
-from pip._internal.cli.status_codes import NO_MATCHES_FOUND, SUCCESS
-from pip._internal.download import PipXmlrpcTransport
-from pip._internal.exceptions import CommandError
 from pip._internal.models.index import PyPI
-from pip._internal.utils.compat import get_terminal_size
-from pip._internal.utils.logging import indent_log
+
+# NOTE: XMLRPC Client is not annotated in typeshed as on 2017-07-17, which is
+#       why we ignore the type on this import
 
 logger = logging.getLogger(__name__)
 
@@ -42,6 +32,12 @@ def __init__(self, *args, **kw):
         self.parser.insert_option_group(0, self.cmd_opts)
 
     def run(self, options, args):
+        # NOTE: XMLRPC Client is not annotated in typeshed as on 2017-07-17, which is
+        #       why we ignore the type on this import
+        from pip._internal.cli.status_codes import NO_MATCHES_FOUND, SUCCESS
+        from pip._internal.exceptions import CommandError
+        from pip._internal.utils.compat import get_terminal_size
+
         if not args:
             raise CommandError('Missing required argument (search query).')
         query = args
@@ -58,6 +54,8 @@ def run(self, options, args):
         return NO_MATCHES_FOUND
 
     def search(self, query, options):
+        from pip._internal.download import PipXmlrpcTransport
+        from pip._vendor.six.moves import xmlrpc_client  # type: ignore
         index_url = options.index
         with self._build_session(options) as session:
             transport = PipXmlrpcTransport(index_url, session)
@@ -72,6 +70,7 @@ def transform_hits(hits):
     packages with the list of versions stored inline. This converts the
     list from pypi into one we can use.
     """
+    from collections import OrderedDict
     packages = OrderedDict()
     for hit in hits:
         name = hit['name']
@@ -97,6 +96,13 @@ def transform_hits(hits):
 def print_results(hits, name_column_width=None, terminal_width=None):
     if not hits:
         return
+
+    import textwrap
+    from pip._vendor import pkg_resources
+    # NOTE: XMLRPC Client is not annotated in typeshed as on 2017-07-17, which is
+    #       why we ignore the type on this import
+    from pip._internal.utils.logging import indent_log
+
     if name_column_width is None:
         name_column_width = max([
             len(hit['name']) + len(highest_version(hit.get('versions', ['-'])))
@@ -132,4 +138,7 @@ def print_results(hits, name_column_width=None, terminal_width=None):
 
 
 def highest_version(versions):
+    from pip._vendor.packaging.version import parse as parse_version
+    # NOTE: XMLRPC Client is not annotated in typeshed as on 2017-07-17, which is
+    #       why we ignore the type on this import
     return max(versions, key=parse_version)
diff --git a/src/pip/_internal/commands/show.py b/src/pip/_internal/commands/show.py
index a18a9020c41..35e14f4301d 100644
--- a/src/pip/_internal/commands/show.py
+++ b/src/pip/_internal/commands/show.py
@@ -1,14 +1,8 @@
 from __future__ import absolute_import
 
 import logging
-import os
-from email.parser import FeedParser
-
-from pip._vendor import pkg_resources
-from pip._vendor.packaging.utils import canonicalize_name
 
 from pip._internal.cli.base_command import Command
-from pip._internal.cli.status_codes import ERROR, SUCCESS
 
 logger = logging.getLogger(__name__)
 
@@ -37,6 +31,9 @@ def __init__(self, *args, **kw):
         self.parser.insert_option_group(0, self.cmd_opts)
 
     def run(self, options, args):
+
+        from pip._internal.cli.status_codes import ERROR, SUCCESS
+
         if not args:
             logger.warning('ERROR: Please provide a package name or names.')
             return ERROR
@@ -56,6 +53,12 @@ def search_packages_info(query):
     pip generated 'installed-files.txt' in the distributions '.egg-info'
     directory.
     """
+    import os
+    from email.parser import FeedParser
+
+    from pip._vendor import pkg_resources
+    from pip._vendor.packaging.utils import canonicalize_name
+
     installed = {}
     for p in pkg_resources.working_set:
         installed[canonicalize_name(p.project_name)] = p
@@ -126,6 +129,9 @@ def print_results(distributions, list_files=False, verbose=False):
     """
     Print the informations from installed distributions found.
     """
+
+    from pip._vendor import pkg_resources
+
     results_printed = False
     for i, dist in enumerate(distributions):
         results_printed = True
diff --git a/src/pip/_internal/commands/uninstall.py b/src/pip/_internal/commands/uninstall.py
index 0cd6f54bd86..fb6bca20932 100644
--- a/src/pip/_internal/commands/uninstall.py
+++ b/src/pip/_internal/commands/uninstall.py
@@ -1,12 +1,6 @@
 from __future__ import absolute_import
 
-from pip._vendor.packaging.utils import canonicalize_name
-
 from pip._internal.cli.base_command import Command
-from pip._internal.exceptions import InstallationError
-from pip._internal.req import parse_requirements
-from pip._internal.req.constructors import install_req_from_line
-from pip._internal.utils.misc import protect_pip_from_modification_on_windows
 
 
 class UninstallCommand(Command):
@@ -45,6 +39,13 @@ def __init__(self, *args, **kw):
         self.parser.insert_option_group(0, self.cmd_opts)
 
     def run(self, options, args):
+        from pip._vendor.packaging.utils import canonicalize_name
+
+        from pip._internal.exceptions import InstallationError
+        from pip._internal.req import parse_requirements
+        from pip._internal.req.constructors import install_req_from_line
+        from pip._internal.utils.misc import protect_pip_from_modification_on_windows
+
         with self._build_session(options) as session:
             reqs_to_uninstall = {}
             for name in args:
diff --git a/src/pip/_internal/commands/wheel.py b/src/pip/_internal/commands/wheel.py
index cd72a3df1a7..576f8c5edb2 100644
--- a/src/pip/_internal/commands/wheel.py
+++ b/src/pip/_internal/commands/wheel.py
@@ -2,18 +2,8 @@
 from __future__ import absolute_import
 
 import logging
-import os
 
-from pip._internal.cache import WheelCache
-from pip._internal.cli import cmdoptions
 from pip._internal.cli.base_command import RequirementCommand
-from pip._internal.exceptions import CommandError, PreviousBuildDirError
-from pip._internal.operations.prepare import RequirementPreparer
-from pip._internal.req import RequirementSet
-from pip._internal.req.req_tracker import RequirementTracker
-from pip._internal.resolve import Resolver
-from pip._internal.utils.temp_dir import TempDirectory
-from pip._internal.wheel import WheelBuilder
 
 logger = logging.getLogger(__name__)
 
@@ -46,6 +36,10 @@ class WheelCommand(RequirementCommand):
     def __init__(self, *args, **kw):
         super(WheelCommand, self).__init__(*args, **kw)
 
+        import os
+
+        from pip._internal.cli import cmdoptions
+
         cmd_opts = self.cmd_opts
 
         cmd_opts.add_option(
@@ -106,6 +100,18 @@ def __init__(self, *args, **kw):
         self.parser.insert_option_group(0, cmd_opts)
 
     def run(self, options, args):
+        import os
+
+        from pip._internal.cache import WheelCache
+        from pip._internal.cli import cmdoptions
+        from pip._internal.exceptions import CommandError, PreviousBuildDirError
+        from pip._internal.operations.prepare import RequirementPreparer
+        from pip._internal.req import RequirementSet
+        from pip._internal.req.req_tracker import RequirementTracker
+        from pip._internal.resolve import Resolver
+        from pip._internal.utils.temp_dir import TempDirectory
+        from pip._internal.wheel import WheelBuilder
+
         cmdoptions.check_install_build_global(options)
 
         index_urls = [options.index_url] + options.extra_index_urls
diff --git a/src/pip/_internal/exceptions.py b/src/pip/_internal/exceptions.py
index 7b291a1e4e4..08d8cfb630b 100644
--- a/src/pip/_internal/exceptions.py
+++ b/src/pip/_internal/exceptions.py
@@ -3,8 +3,6 @@
 
 from itertools import chain, groupby, repeat
 
-from pip._vendor.six import iteritems
-
 from pip._internal.utils.typing import MYPY_CHECK_RUNNING
 
 if MYPY_CHECK_RUNNING:
@@ -240,6 +238,7 @@ def hash_then_or(hash_name):
             return chain([hash_name], repeat('    or'))
 
         lines = []
+        from pip._vendor.six import iteritems
         for hash_name, expecteds in iteritems(self.allowed):
             prefix = hash_then_or(hash_name)
             lines.extend(('        Expected %s %s' % (next(prefix), e))
diff --git a/src/pip/_internal/utils/deprecation.py b/src/pip/_internal/utils/deprecation.py
index 8c896f8cee5..627124056e0 100644
--- a/src/pip/_internal/utils/deprecation.py
+++ b/src/pip/_internal/utils/deprecation.py
@@ -6,8 +6,6 @@
 import logging
 import warnings
 
-from pip._vendor.packaging.version import parse
-
 from pip import __version__ as current_version
 from pip._internal.utils.typing import MYPY_CHECK_RUNNING
 
@@ -87,6 +85,8 @@ def deprecated(reason, replacement, gone_in, issue=None):
         url = "https://github.com/pypa/pip/issues/" + str(issue)
         message += " You can find discussion regarding this at {}.".format(url)
 
+    from pip._vendor.packaging.version import parse
+
     # Raise as an error if it has to be removed.
     if gone_in is not None and parse(current_version) >= parse(gone_in):
         raise PipDeprecationWarning(message)
diff --git a/src/pip/_internal/utils/misc.py b/src/pip/_internal/utils/misc.py
index 42f324bc412..19b921975da 100644
--- a/src/pip/_internal/utils/misc.py
+++ b/src/pip/_internal/utils/misc.py
@@ -57,8 +57,7 @@
            'is_svn_page', 'file_contents',
            'split_leading_dir', 'has_leading_dir',
            'normalize_path',
-           'renames', 'get_prog',
-           'unzip_file', 'untar_file', 'unpack_file', 'call_subprocess',
+           'renames', 'unzip_file', 'untar_file', 'unpack_file', 'call_subprocess',
            'captured_stdout', 'ensure_dir',
            'ARCHIVE_EXTENSIONS', 'SUPPORTED_EXTENSIONS', 'WHEEL_EXTENSION',
            'get_installed_version', 'remove_auth_from_url']
@@ -101,19 +100,6 @@ def ensure_dir(path):
             raise
 
 
-def get_prog():
-    # type: () -> str
-    try:
-        prog = os.path.basename(sys.argv[0])
-        if prog in ('__main__.py', '-c'):
-            return "%s -m pip" % sys.executable
-        else:
-            return prog
-    except (AttributeError, TypeError, IndexError):
-        pass
-    return 'pip'
-
-
 # Retry every half second for up to 3 seconds
 @retry(stop_max_delay=3000, wait_fixed=500)
 def rmtree(dir, ignore_errors=False):
diff --git a/src/pip/_internal/utils/misc_fast_import.py b/src/pip/_internal/utils/misc_fast_import.py
new file mode 100644
index 00000000000..d6b67241eea
--- /dev/null
+++ b/src/pip/_internal/utils/misc_fast_import.py
@@ -0,0 +1,15 @@
+import os
+import sys
+
+
+def get_prog():
+    # type: () -> str
+    try:
+        prog = os.path.basename(sys.argv[0])
+        if prog in ('__main__.py', '-c'):
+            return "%s -m pip" % sys.executable
+        else:
+            return prog
+    except (AttributeError, TypeError, IndexError):
+        pass
+    return 'pip'
diff --git a/tests/functional/test_help.py b/tests/functional/test_help.py
index 9e3dbcde8c9..9ac4bd0bc16 100644
--- a/tests/functional/test_help.py
+++ b/tests/functional/test_help.py
@@ -1,7 +1,7 @@
 import pytest
 from mock import Mock
 
-from pip._internal.cli.base_command import ERROR, SUCCESS
+from pip._internal.cli.status_codes import ERROR, SUCCESS
 from pip._internal.commands import commands_dict as commands
 from pip._internal.commands.help import HelpCommand
 from pip._internal.exceptions import CommandError
diff --git a/tests/unit/test_utils.py b/tests/unit/test_utils.py
index f1abddd988e..c371109c1ca 100644
--- a/tests/unit/test_utils.py
+++ b/tests/unit/test_utils.py
@@ -27,10 +27,11 @@
 from pip._internal.utils.hashes import Hashes, MissingHashes
 from pip._internal.utils.misc import (
     call_subprocess, egg_link_path, ensure_dir, format_command_args,
-    get_installed_distributions, get_prog, normalize_path, redact_netloc,
+    get_installed_distributions, normalize_path, redact_netloc,
     redact_password_from_url, remove_auth_from_url, rmtree,
     split_auth_from_netloc, untar_file, unzip_file,
 )
+from pip._internal.utils.misc_fast_import import get_prog
 from pip._internal.utils.packaging import check_dist_requires_python
 from pip._internal.utils.temp_dir import AdjacentTempDirectory, TempDirectory
 from pip._internal.utils.ui import SpinnerInterface