gh-90815: Add mimalloc memory allocator (#109914)

* Add mimalloc v2.12

Modified src/alloc.c to remove include of alloc-override.c and not
compile new handler.

Did not include the following files:

 - include/mimalloc-new-delete.h
 - include/mimalloc-override.h
 - src/alloc-override-osx.c
 - src/alloc-override.c
 - src/static.c
 - src/region.c

mimalloc is thread safe and shares a single heap across all runtimes,
therefore finalization and getting global allocated blocks across all
runtimes is different.

* mimalloc: minimal changes for use in Python:

 - remove debug spam for freeing large allocations
 - use same bytes (0xDD) for freed allocations in CPython and mimalloc
   This is important for the test_capi debug memory tests

* Don't export mimalloc symbol in libpython.
* Enable mimalloc as Python allocator option.
* Add mimalloc MIT license.
* Log mimalloc in Lib/test/pythoninfo.py.
* Document new mimalloc support.
* Use macro defs for exports as done in:
  https://github.com/python/cpython/pull/31164/

Co-authored-by: Sam Gross <colesbury@gmail.com>
Co-authored-by: Christian Heimes <christian@python.org>
Co-authored-by: Victor Stinner <vstinner@python.org>

2 files changed, 22 insertions, 0 deletions

diff --git a/Doc/c-api/init_config.rst b/Doc/c-api/init_config.rst
index 1d4e0fb..0c2ed8a 100644
--- a/Doc/c-api/init_config.rst
+++ b/Doc/c-api/init_config.rst
@@ -253,11 +253,21 @@ PyPreConfig
       * ``PYMEM_ALLOCATOR_PYMALLOC_DEBUG`` (``6``): :ref:`Python pymalloc
         memory allocator <pymalloc>` with :ref:`debug hooks
         <pymem-debug-hooks>`.
+      * ``PYMEM_ALLOCATOR_MIMALLOC`` (``6``): use ``mimalloc``, a fast
+        malloc replacement.
+      * ``PYMEM_ALLOCATOR_MIMALLOC_DEBUG`` (``7``): use ``mimalloc``, a fast
+        malloc replacement with :ref:`debug hooks <pymem-debug-hooks>`.
+
 
       ``PYMEM_ALLOCATOR_PYMALLOC`` and ``PYMEM_ALLOCATOR_PYMALLOC_DEBUG`` are
       not supported if Python is :option:`configured using --without-pymalloc
       <--without-pymalloc>`.
 
+      ``PYMEM_ALLOCATOR_MIMALLOC`` and ``PYMEM_ALLOCATOR_MIMALLOC_DEBUG`` are
+      not supported if Python is :option:`configured using --without-mimalloc
+      <--without-mimalloc>` or if the underlying atomic support isn't
+      available.
+
       See :ref:`Memory Management <memory>`.
 
       Default: ``PYMEM_ALLOCATOR_NOT_SET``.
diff --git a/Doc/c-api/memory.rst b/Doc/c-api/memory.rst
index 52ef417..1f392e5 100644
--- a/Doc/c-api/memory.rst
+++ b/Doc/c-api/memory.rst
@@ -391,6 +391,8 @@ Legend:
 * ``malloc``: system allocators from the standard C library, C functions:
   :c:func:`malloc`, :c:func:`calloc`, :c:func:`realloc` and :c:func:`free`.
 * ``pymalloc``: :ref:`pymalloc memory allocator <pymalloc>`.
+* ``mimalloc``: :ref:`mimalloc memory allocator <mimalloc>`.  The pymalloc
+  allocator will be used if mimalloc support isn't available.
 * "+ debug": with :ref:`debug hooks on the Python memory allocators
   <pymem-debug-hooks>`.
 * "Debug build": :ref:`Python build in debug mode <debug-build>`.
@@ -672,6 +674,16 @@ Customize pymalloc Arena Allocator
 
    Set the arena allocator.
 
+.. _mimalloc:
+
+The mimalloc allocator
+======================
+
+.. versionadded:: 3.13
+
+Python supports the mimalloc allocator when the underlying platform support is available.
+mimalloc "is a general purpose allocator with excellent performance characteristics.
+Initially developed by Daan Leijen for the runtime systems of the Koka and Lean languages."
 
 tracemalloc C API
 =================