Merge branch 'master' of https://github.com/python/cpython

Doc/whatsnew/3.10.rst

@@ -103,6 +103,11 @@ Improved Modules
 Optimizations
 =============
 
+* The :mod:`runpy` module now imports fewer modules.
+  The ``python3 -m module-name`` command startup time is 1.3x faster in
+  average.
+  (Contributed by Victor Stinner in :issue:`41006`.)
+
 
 Deprecated
 ==========

Lib/importlib/_abc.py

@@ -0,0 +1,50 @@
+"""Subset of importlib.abc used to reduce importlib.util imports."""
+from . import _bootstrap
+import abc
+
+
+class Loader(metaclass=abc.ABCMeta):
+
+    """Abstract base class for import loaders."""
+
+    def create_module(self, spec):
+        """Return a module to initialize and into which to load.
+
+        This method should raise ImportError if anything prevents it
+        from creating a new module.  It may return None to indicate
+        that the spec should create the new module.
+        """
+        # By default, defer to default semantics for the new module.
+        return None
+
+    # We don't define exec_module() here since that would break
+    # hasattr checks we do to support backward compatibility.
+
+    def load_module(self, fullname):
+        """Return the loaded module.
+
+        The module must be added to sys.modules and have import-related
+        attributes set properly.  The fullname is a str.
+
+        ImportError is raised on failure.
+
+        This method is deprecated in favor of loader.exec_module(). If
+        exec_module() exists then it is used to provide a backwards-compatible
+        functionality for this method.
+
+        """
+        if not hasattr(self, 'exec_module'):
+            raise ImportError
+        return _bootstrap._load_module_shim(self, fullname)
+
+    def module_repr(self, module):
+        """Return a module's repr.
+
+        Used by the module type when the method does not raise
+        NotImplementedError.
+
+        This method is deprecated.
+
+        """
+        # The exception will cause ModuleType.__repr__ to ignore this method.
+        raise NotImplementedError

Lib/importlib/abc.py

@@ -12,6 +12,7 @@ try:
     import _frozen_importlib_external
 except ImportError:
     _frozen_importlib_external = _bootstrap_external
+from ._abc import Loader
 import abc
 import warnings
 from typing import Protocol, runtime_checkable
@@ -134,53 +135,6 @@ class PathEntryFinder(Finder):
 _register(PathEntryFinder, machinery.FileFinder)
 
 
-class Loader(metaclass=abc.ABCMeta):
-
-    """Abstract base class for import loaders."""
-
-    def create_module(self, spec):
-        """Return a module to initialize and into which to load.
-
-        This method should raise ImportError if anything prevents it
-        from creating a new module.  It may return None to indicate
-        that the spec should create the new module.
-        """
-        # By default, defer to default semantics for the new module.
-        return None
-
-    # We don't define exec_module() here since that would break
-    # hasattr checks we do to support backward compatibility.
-
-    def load_module(self, fullname):
-        """Return the loaded module.
-
-        The module must be added to sys.modules and have import-related
-        attributes set properly.  The fullname is a str.
-
-        ImportError is raised on failure.
-
-        This method is deprecated in favor of loader.exec_module(). If
-        exec_module() exists then it is used to provide a backwards-compatible
-        functionality for this method.
-
-        """
-        if not hasattr(self, 'exec_module'):
-            raise ImportError
-        return _bootstrap._load_module_shim(self, fullname)
-
-    def module_repr(self, module):
-        """Return a module's repr.
-
-        Used by the module type when the method does not raise
-        NotImplementedError.
-
-        This method is deprecated.
-
-        """
-        # The exception will cause ModuleType.__repr__ to ignore this method.
-        raise NotImplementedError
-
-
 class ResourceLoader(Loader):
 
     """Abstract base class for loaders which can return data from their

Lib/importlib/util.py

@@ -1,5 +1,5 @@
 """Utility code for constructing importers, etc."""
-from . import abc
+from ._abc import Loader
 from ._bootstrap import module_from_spec
 from ._bootstrap import _resolve_name
 from ._bootstrap import spec_from_loader
@@ -263,7 +263,7 @@ class _LazyModule(types.ModuleType):
         delattr(self, attr)
 
 
-class LazyLoader(abc.Loader):
+class LazyLoader(Loader):
 
     """A loader that creates a module which defers loading until attribute access."""
 

Lib/test/test_importlib/test_spec.py

@@ -650,8 +650,8 @@ class FactoryTests:
         # Need to use a circuitous route to get at importlib.machinery to make
         # sure the same class object is used in the isinstance() check as
         # would have been used to create the loader.
-        self.assertIsInstance(spec.loader,
-                              self.util.abc.machinery.SourceFileLoader)
+        SourceFileLoader = self.util.spec_from_file_location.__globals__['SourceFileLoader']
+        self.assertIsInstance(spec.loader, SourceFileLoader)
         self.assertEqual(spec.loader.name, self.name)
         self.assertEqual(spec.loader.path, self.path)
         self.assertEqual(spec.origin, self.path)

Misc/NEWS.d/next/Core and Builtins/2020-06-18-00-07-09.bpo-41006.H-wN-d.rst

@@ -0,0 +1,2 @@
+The ``encodings.latin_1`` module is no longer imported at startup. Now it is
+only imported when it is the filesystem encoding or the stdio encoding.

Python/pylifecycle.c

@@ -1939,7 +1939,6 @@ static PyStatus
 init_sys_streams(PyThreadState *tstate)
 {
     PyObject *iomod = NULL;
-    PyObject *m;
     PyObject *std = NULL;
     int fd;
     PyObject * encoding_attr;
@@ -1959,18 +1958,6 @@ init_sys_streams(PyThreadState *tstate)
     }
 #endif
 
-    /* Hack to avoid a nasty recursion issue when Python is invoked
-       in verbose mode: pre-import the Latin-1 and UTF-8 codecs */
-    if ((m = PyImport_ImportModule("encodings.utf_8")) == NULL) {
-        goto error;
-    }
-    Py_DECREF(m);
-
-    if (!(m = PyImport_ImportModule("encodings.latin_1"))) {
-        goto error;
-    }
-    Py_DECREF(m);
-
     if (!(iomod = PyImport_ImportModule("io"))) {
         goto error;
     }