Merge branch 'main' into bpo-28879

Author: Yoav11

Doc/library/gc.rst

@@ -60,7 +60,7 @@ The :mod:`gc` module provides the following functions:
    The effect of calling ``gc.collect()`` while the interpreter is already
    performing a collection is undefined.
 
-   .. versionchanged:: 3.13
+   .. versionchanged:: 3.14
       ``generation=1`` performs an increment of collection.
 
 
@@ -83,13 +83,13 @@ The :mod:`gc` module provides the following functions:
    returned. If *generation* is not ``None``, return only the objects as follows:
 
    * 0: All objects in the young generation
-   * 1: No objects, as there is no generation 1 (as of Python 3.13)
+   * 1: No objects, as there is no generation 1 (as of Python 3.14)
    * 2: All objects in the old generation
 
    .. versionchanged:: 3.8
       New *generation* parameter.
 
-   .. versionchanged:: 3.13
+   .. versionchanged:: 3.14
       Generation 1 is removed
 
    .. audit-event:: gc.get_objects generation gc.get_objects
@@ -142,7 +142,7 @@ The :mod:`gc` module provides the following functions:
 
    See `Garbage collector design <https://devguide.python.org/garbage_collector>`_ for more information.
 
-   .. versionchanged:: 3.13
+   .. versionchanged:: 3.14
       *threshold2* is ignored
 
 

Doc/whatsnew/3.14.rst

@@ -1058,6 +1058,30 @@ free-threaded build and false for the GIL-enabled build.
 
 (Contributed by Neil Schemenauer and Kumar Aditya in :gh:`130010`.)
 
+.. _whatsnew314-incremental-gc:
+
+Incremental garbage collection
+------------------------------
+
+The cycle garbage collector is now incremental.
+This means that maximum pause times are reduced
+by an order of magnitude or more for larger heaps.
+
+There are now only two generations: young and old.
+When :func:`gc.collect` is not called directly, the
+GC is invoked a little less frequently. When invoked, it
+collects the young generation and an increment of the
+old generation, instead of collecting one or more generations.
+
+The behavior of :func:`!gc.collect` changes slightly:
+
+* ``gc.collect(1)``: Performs an increment of garbage collection,
+  rather than collecting generation 1.
+* Other calls to :func:`!gc.collect` are unchanged.
+
+(Contributed by Mark Shannon in :gh:`108362`.)
+
+
 Other language changes
 ======================
 
@@ -1486,6 +1510,36 @@ functools
   (Contributed by Sayandip Dutta in :gh:`125916`.)
 
 
+gc
+--
+
+The cyclic garbage collector is now incremental,
+which changes the meaning of the results of
+:meth:`~gc.get_threshold` and :meth:`~gc.set_threshold`
+as well as :meth:`~gc.get_count` and :meth:`~gc.get_stats`.
+
+* For backwards compatibility, :meth:`~gc.get_threshold` continues to return
+  a three-item tuple.
+  The first value is the threshold for young collections, as before;
+  the second value determines the rate at which the old collection is scanned
+  (the default is 10, and higher values mean that the old collection
+  is scanned more slowly).
+  The third value is meaningless and is always zero.
+
+* :meth:`~gc.set_threshold` ignores any items after the second.
+
+* :meth:`~gc.get_count` and :meth:`~gc.get_stats` continue to return
+  the same format of results.
+  The only difference is that instead of the results referring to
+  the young, aging and old generations,
+  the results refer to the young generation
+  and the aging and collecting spaces of the old generation.
+
+In summary, code that attempted to manipulate the behavior of the cycle GC
+may not work exactly as intended, but it is very unlikely to be harmful.
+All other code will work just fine.
+
+
 getopt
 ------
 
@@ -2233,6 +2287,7 @@ asyncio
   (Contributed by Yury Selivanov, Pablo Galindo Salgado, and Łukasz Langa
   in :gh:`91048`.)
 
+
 base64
 ------
 
@@ -2241,6 +2296,15 @@ base64
   (Contributed by Bénédikt Tran, Chris Markiewicz, and Adam Turner in :gh:`118761`.)
 
 
+gc
+--
+
+* The new :ref:`incremental garbage collector <whatsnew314-incremental-gc>`
+  means that maximum pause times are reduced
+  by an order of magnitude or more for larger heaps.
+  (Contributed by Mark Shannon in :gh:`108362`.)
+
+
 io
 ---
 * :mod:`io` which provides the built-in :func:`open` makes less system calls
@@ -2707,6 +2771,13 @@ Changes in the Python API
   Wrap it in :func:`staticmethod` if you want to preserve the old behavior.
   (Contributed by Serhiy Storchaka and Dominykas Grigonis in :gh:`121027`.)
 
+* The :ref:`garbage collector is now incremental <whatsnew314-incremental-gc>`,
+  which means that the behavior of :func:`gc.collect` changes slightly:
+
+  * ``gc.collect(1)``: Performs an increment of garbage collection,
+    rather than collecting generation 1.
+  * Other calls to :func:`!gc.collect` are unchanged.
+
 * The :func:`locale.nl_langinfo` function now sets temporarily the ``LC_CTYPE``
   locale in some cases.
   This temporary change affects other threads.

Lib/hashlib.py

@@ -80,6 +80,11 @@
 }
 
 def __get_builtin_constructor(name):
+    if not isinstance(name, str):
+        # Since this function is only used by new(), we use the same
+        # exception as _hashlib.new() when 'name' is of incorrect type.
+        err = f"new() argument 'name' must be str, not {type(name).__name__}"
+        raise TypeError(err)
     cache = __builtin_constructor_cache
     constructor = cache.get(name)
     if constructor is not None:
@@ -120,10 +125,13 @@ def __get_builtin_constructor(name):
     if constructor is not None:
         return constructor
 
-    raise ValueError('unsupported hash type ' + name)
+    # Keep the message in sync with hashlib.h::HASHLIB_UNSUPPORTED_ALGORITHM.
+    raise ValueError(f'unsupported hash algorithm {name}')
 
 
 def __get_openssl_constructor(name):
+    # This function is only used until the module has been initialized.
+    assert isinstance(name, str), "invalid call to __get_openssl_constructor()"
     if name in __block_openssl_constructor:
         # Prefer our builtin blake2 implementation.
         return __get_builtin_constructor(name)
@@ -154,6 +162,8 @@ def __hash_new(name, *args, **kwargs):
     optionally initialized with data (which must be a bytes-like object).
     """
     if name in __block_openssl_constructor:
+        # __block_openssl_constructor is expected to contain strings only
+        assert isinstance(name, str), f"unexpected name: {name}"
         # Prefer our builtin blake2 implementation.
         return __get_builtin_constructor(name)(*args, **kwargs)
     try:

Lib/hmac.py

@@ -26,6 +26,16 @@
 digest_size = None
 
 
+def _is_shake_constructor(digest_like):
+    if isinstance(digest_like, str):
+        name = digest_like
+    else:
+        h = digest_like() if callable(digest_like) else digest_like.new()
+        if not isinstance(name := getattr(h, "name", None), str):
+            return False
+    return name.startswith(("shake", "SHAKE"))
+
+
 def _get_digest_constructor(digest_like):
     if callable(digest_like):
         return digest_like
@@ -109,6 +119,8 @@ def _init_old(self, key, msg, digestmod):
         import warnings
 
         digest_cons = _get_digest_constructor(digestmod)
+        if _is_shake_constructor(digest_cons):
+            raise ValueError(f"unsupported hash algorithm {digestmod}")
 
         self._hmac = None
         self._outer = digest_cons()
@@ -243,6 +255,8 @@ def digest(key, msg, digest):
 
 def _compute_digest_fallback(key, msg, digest):
     digest_cons = _get_digest_constructor(digest)
+    if _is_shake_constructor(digest_cons):
+        raise ValueError(f"unsupported hash algorithm {digest}")
     inner = digest_cons()
     outer = digest_cons()
     blocksize = getattr(inner, 'block_size', 64)

Lib/test/test_hashlib.py

@@ -343,7 +343,9 @@ def test_clinic_signature_errors(self):
 
     def test_unknown_hash(self):
         self.assertRaises(ValueError, hashlib.new, 'spam spam spam spam spam')
-        self.assertRaises(TypeError, hashlib.new, 1)
+        # ensure that the exception message remains consistent
+        err = re.escape("new() argument 'name' must be str, not int")
+        self.assertRaisesRegex(TypeError, err, hashlib.new, 1)
 
     def test_new_upper_to_lower(self):
         self.assertEqual(hashlib.new("SHA256").name, "sha256")
@@ -370,7 +372,9 @@ def test_get_builtin_constructor(self):
                 sys.modules['_md5'] = _md5
             else:
                 del sys.modules['_md5']
-        self.assertRaises(TypeError, get_builtin_constructor, 3)
+        # ensure that the exception message remains consistent
+        err = re.escape("new() argument 'name' must be str, not int")
+        self.assertRaises(TypeError, err, get_builtin_constructor, 3)
         constructor = get_builtin_constructor('md5')
         self.assertIs(constructor, _md5.md5)
         self.assertEqual(sorted(builtin_constructor_cache), ['MD5', 'md5'])

Lib/test/test_hmac.py

@@ -960,7 +960,7 @@ def raiser():
         with self.assertRaisesRegex(RuntimeError, "custom exception"):
             func(b'key', b'msg', raiser)
 
-        with self.assertRaisesRegex(ValueError, 'hash type'):
+        with self.assertRaisesRegex(ValueError, 'unsupported hash algorithm'):
             func(b'key', b'msg', 'unknown')
 
         with self.assertRaisesRegex(AttributeError, 'new'):

Lib/test/test_remote_pdb.py

@@ -11,7 +11,7 @@
 import unittest
 import unittest.mock
 from contextlib import closing, contextmanager, redirect_stdout, redirect_stderr, ExitStack
-from test.support import is_wasi, cpython_only, force_color, requires_subprocess, SHORT_TIMEOUT
+from test.support import is_wasi, cpython_only, force_color, requires_subprocess, SHORT_TIMEOUT, subTests
 from test.support.os_helper import TESTFN, unlink
 from typing import List
 
@@ -279,37 +279,50 @@ def test_handling_other_message(self):
             expected_stdout="Some message.\n",
         )
 
-    def test_handling_help_for_command(self):
-        """Test handling a request to display help for a command."""
+    @unittest.skipIf(sys.flags.optimize >= 2, "Help not available for -OO")
+    @subTests(
+        "help_request,expected_substring",
+        [
+            # a request to display help for a command
+            ({"help": "ll"}, "Usage: ll | longlist"),
+            # a request to display a help overview
+            ({"help": ""}, "type help <topic>"),
+            # a request to display the full PDB manual
+            ({"help": "pdb"}, ">>> import pdb"),
+        ],
+    )
+    def test_handling_help_when_available(self, help_request, expected_substring):
+        """Test handling help requests when help is available."""
         incoming = [
-            ("server", {"help": "ll"}),
+            ("server", help_request),
         ]
         self.do_test(
             incoming=incoming,
             expected_outgoing=[],
-            expected_stdout_substring="Usage: ll | longlist",
+            expected_stdout_substring=expected_substring,
         )
 
-    def test_handling_help_without_a_specific_topic(self):
-        """Test handling a request to display a help overview."""
+    @unittest.skipIf(sys.flags.optimize < 2, "Needs -OO")
+    @subTests(
+        "help_request,expected_substring",
+        [
+            # a request to display help for a command
+            ({"help": "ll"}, "No help for 'll'"),
+            # a request to display a help overview
+            ({"help": ""}, "Undocumented commands"),
+            # a request to display the full PDB manual
+            ({"help": "pdb"}, "No help for 'pdb'"),
+        ],
+    )
+    def test_handling_help_when_not_available(self, help_request, expected_substring):
+        """Test handling help requests when help is not available."""
         incoming = [
-            ("server", {"help": ""}),
+            ("server", help_request),
         ]
         self.do_test(
             incoming=incoming,
             expected_outgoing=[],
-            expected_stdout_substring="type help <topic>",
-        )
-
-    def test_handling_help_pdb(self):
-        """Test handling a request to display the full PDB manual."""
-        incoming = [
-            ("server", {"help": "pdb"}),
-        ]
-        self.do_test(
-            incoming=incoming,
-            expected_outgoing=[],
-            expected_stdout_substring=">>> import pdb",
+            expected_stdout_substring=expected_substring,
         )
 
     def test_handling_pdb_prompts(self):

Misc/NEWS.d/next/Library/2025-07-20-10-21-49.gh-issue-136787._0Rbp_.rst

@@ -0,0 +1,4 @@
+:mod:`hashlib`: improve exception messages when a hash algorithm is not
+recognized, blocked by the current security policy or incompatible with
+the desired operation (for instance, using HMAC with SHAKE).
+Patch by Bénédikt Tran.