gh-118830: Bump DEFAULT_PROTOCOL to 5 (#118830)

mdkcore0 · mdkcore0 · commit a19e48a3561b · 2024-06-18T00:12:24.000-03:00
diff --git a/Doc/library/pickle.rst b/Doc/library/pickle.rst
@@ -156,13 +156,14 @@ to read the pickle produced.
 
 * Protocol version 4 was added in Python 3.4.  It adds support for very large
   objects, pickling more kinds of objects, and some data format
-  optimizations.  It is the default protocol starting with Python 3.8.
+  optimizations.  This was the default protocol in Python 3.8--3.14.
   Refer to :pep:`3154` for information about improvements brought by
   protocol 4.
 
 * Protocol version 5 was added in Python 3.8.  It adds support for out-of-band
-  data and speedup for in-band data.  Refer to :pep:`574` for information about
-  improvements brought by protocol 5.
+  data and speedup for in-band data.  It is the default protocol starting with
+  Python 3.14.  Refer to :pep:`574` for information about improvements brought
+  by protocol 5.
 
 .. note::
    Serialization is a more primitive notion than persistence; although
@@ -199,8 +200,10 @@ The :mod:`pickle` module provides the following constants:
 
    An integer, the default :ref:`protocol version <pickle-protocols>` used
    for pickling.  May be less than :data:`HIGHEST_PROTOCOL`.  Currently the
-   default protocol is 4, first introduced in Python 3.4 and incompatible
-   with previous versions.
+   default protocol is 5, introduced in Python 3.8 and incompatible
+   with previous versions. This version introduces support for out-of-band
+   buffers, where :pep:`3118`-compatible data can be transmitted separately
+   from the main pickle stream.
 
    .. versionchanged:: 3.0
 
@@ -210,6 +213,10 @@ The :mod:`pickle` module provides the following constants:
 
       The default protocol is 4.
 
+   .. versionchanged:: 3.14
+
+      The default protocol is 5.
+
 The :mod:`pickle` module provides the following functions to make the pickling
 process more convenient:
 
diff --git a/Doc/whatsnew/3.14.rst b/Doc/whatsnew/3.14.rst
@@ -115,6 +115,8 @@ symtable
 Optimizations
 =============
 
+* Set the default protocol version on the :mod:`pickle` module to 5.
+  For more details, please see :ref:`pickle protocols <pickle-protocols>`.
 
 
 
diff --git a/Lib/pickle.py b/Lib/pickle.py
@@ -51,7 +51,7 @@
 bytes_types = (bytes, bytearray)
 
 # These are purely informational; no code uses these.
-format_version = "4.0"                  # File format version we write
+format_version = "5.0"                  # File format version we write
 compatible_formats = ["1.0",            # Original protocol 0
                       "1.1",            # Protocol 0 with INST added
                       "1.2",            # Original protocol 1
@@ -68,7 +68,7 @@
 # The protocol we write by default.  May be less than HIGHEST_PROTOCOL.
 # Only bump this if the oldest still supported version of Python already
 # includes it.
-DEFAULT_PROTOCOL = 4
+DEFAULT_PROTOCOL = 5
 
 class PickleError(Exception):
     """A common base class for the other pickling exceptions."""
@@ -408,7 +408,7 @@ def __init__(self, file, protocol=None, *, fix_imports=True,
 
         The optional *protocol* argument tells the pickler to use the
         given protocol; supported protocols are 0, 1, 2, 3, 4 and 5.
-        The default protocol is 4. It was introduced in Python 3.4, and
+        The default protocol is 5. It was introduced in Python 3.8, and
         is incompatible with previous versions.
 
         Specifying a negative protocol version selects the highest
diff --git a/Misc/NEWS.d/next/Library/2024-05-21-23-39-22.gh-issue-118830.YTqvEo.rst b/Misc/NEWS.d/next/Library/2024-05-21-23-39-22.gh-issue-118830.YTqvEo.rst
@@ -0,0 +1 @@
+Bump :mod:`pickle` default protocol to ``5``.
diff --git a/Modules/_pickle.c b/Modules/_pickle.c
@@ -40,7 +40,7 @@ class _pickle.UnpicklerMemoProxy "UnpicklerMemoProxyObject *" ""
    already includes it. */
 enum {
     HIGHEST_PROTOCOL = 5,
-    DEFAULT_PROTOCOL = 4
+    DEFAULT_PROTOCOL = 5
 };
 
 #ifdef MS_WINDOWS
@@ -4693,7 +4693,7 @@ This takes a binary file for writing a pickle data stream.
 
 The optional *protocol* argument tells the pickler to use the given
 protocol; supported protocols are 0, 1, 2, 3, 4 and 5.  The default
-protocol is 4. It was introduced in Python 3.4, and is incompatible
+protocol is 5. It was introduced in Python 3.8, and is incompatible
 with previous versions.
 
 Specifying a negative protocol version selects the highest protocol
@@ -7504,7 +7504,7 @@ be more efficient.
 
 The optional *protocol* argument tells the pickler to use the given
 protocol; supported protocols are 0, 1, 2, 3, 4 and 5.  The default
-protocol is 4. It was introduced in Python 3.4, and is incompatible
+protocol is 5. It was introduced in Python 3.8, and is incompatible
 with previous versions.
 
 Specifying a negative protocol version selects the highest protocol
@@ -7575,7 +7575,7 @@ Return the pickled representation of the object as a bytes object.
 
 The optional *protocol* argument tells the pickler to use the given
 protocol; supported protocols are 0, 1, 2, 3, 4 and 5.  The default
-protocol is 4. It was introduced in Python 3.4, and is incompatible
+protocol is 5. It was introduced in Python 3.8, and is incompatible
 with previous versions.
 
 Specifying a negative protocol version selects the highest protocol

Original file line number	Diff line number	Diff line change
`@@ -0,0 +1 @@`
	`1`	+Bump :mod:`pickle` default protocol to ``5``.