Issue #3329: Implement the PEP 445

Add new enum:

* PyMemAllocatorDomain

Add new structures:

* PyMemAllocator
* PyObjectArenaAllocator

Add new functions:

* PyMem_RawMalloc(), PyMem_RawRealloc(), PyMem_RawFree()
* PyMem_GetAllocator(), PyMem_SetAllocator()
* PyObject_GetArenaAllocator(), PyObject_SetArenaAllocator()
* PyMem_SetupDebugHooks()

Changes:

* PyMem_Malloc()/PyObject_Realloc() now always call malloc()/realloc(), instead
  of calling PyObject_Malloc()/PyObject_Realloc() in debug mode.
* PyObject_Malloc()/PyObject_Realloc() now falls back to
  PyMem_Malloc()/PyMem_Realloc() for allocations larger than 512 bytes.
* Redesign debug checks on memory block allocators as hooks, instead of using C
  macros

Doc/c-api/memory.rst

@@ -84,6 +84,48 @@ the C library allocator as shown in the previous example, the allocated memory
 for the I/O buffer escapes completely the Python memory manager.
 
 
+Raw Memory Interface
+====================
+
+The following function sets are wrappers to the system allocator. These
+functions are thread-safe, the :term:`GIL <global interpreter lock>` does not
+need to be held.
+
+The default raw memory block allocator uses the following functions:
+:c:func:`malloc`, :c:func:`realloc` and :c:func:`free`; call ``malloc(1)`` when
+requesting zero bytes.
+
+.. versionadded:: 3.4
+
+.. c:function:: void* PyMem_RawMalloc(size_t n)
+
+   Allocates *n* bytes and returns a pointer of type :c:type:`void\*` to the
+   allocated memory, or *NULL* if the request fails. Requesting zero bytes
+   returns a distinct non-*NULL* pointer if possible, as if
+   ``PyMem_RawMalloc(1)`` had been called instead. The memory will not have
+   been initialized in any way.
+
+
+.. c:function:: void* PyMem_RawRealloc(void *p, size_t n)
+
+   Resizes the memory block pointed to by *p* to *n* bytes. The contents will
+   be unchanged to the minimum of the old and the new sizes. If *p* is *NULL*,
+   the call is equivalent to ``PyMem_RawMalloc(n)``; else if *n* is equal to
+   zero, the memory block is resized but is not freed, and the returned pointer
+   is non-*NULL*. Unless *p* is *NULL*, it must have been returned by a
+   previous call to :c:func:`PyMem_RawMalloc` or :c:func:`PyMem_RawRealloc`. If
+   the request fails, :c:func:`PyMem_RawRealloc` returns *NULL* and *p* remains
+   a valid pointer to the previous memory area.
+
+
+.. c:function:: void PyMem_RawFree(void *p)
+
+   Frees the memory block pointed to by *p*, which must have been returned by a
+   previous call to :c:func:`PyMem_RawMalloc` or :c:func:`PyMem_RawRealloc`.
+   Otherwise, or if ``PyMem_Free(p)`` has been called before, undefined
+   behavior occurs. If *p* is *NULL*, no operation is performed.
+
+
 .. _memoryinterface:
 
 Memory Interface
@@ -91,8 +133,16 @@ Memory Interface
 
 The following function sets, modeled after the ANSI C standard, but specifying
 behavior when requesting zero bytes, are available for allocating and releasing
-memory from the Python heap:
+memory from the Python heap.
+
+The default memory block allocator uses the following functions:
+:c:func:`malloc`, :c:func:`realloc` and :c:func:`free`; call ``malloc(1)`` when
+requesting zero bytes.
+
+.. warning::
 
+   The :term:`GIL <global interpreter lock>` must be held when using these
+   functions.
 
 .. c:function:: void* PyMem_Malloc(size_t n)
 
@@ -155,6 +205,125 @@ versions and is therefore deprecated in extension modules.
 :c:func:`PyMem_NEW`, :c:func:`PyMem_RESIZE`, :c:func:`PyMem_DEL`.
 
 
+Customize Memory Allocators
+===========================
+
+.. versionadded:: 3.4
+
+.. c:type:: PyMemAllocator
+
+   Structure used to describe a memory block allocator. The structure has
+   four fields:
+
+   +----------------------------------------------------------+---------------------------------------+
+   | Field                                                    | Meaning                               |
+   +==========================================================+=======================================+
+   | ``void *ctx``                                            | user context passed as first argument |
+   +----------------------------------------------------------+---------------------------------------+
+   | ``void* malloc(void *ctx, size_t size)``                 | allocate a memory block               |
+   +----------------------------------------------------------+---------------------------------------+
+   | ``void* realloc(void *ctx, void *ptr, size_t new_size)`` | allocate or resize a memory block     |
+   +----------------------------------------------------------+---------------------------------------+
+   | ``void free(void *ctx, void *ptr)``                      | free a memory block                   |
+   +----------------------------------------------------------+---------------------------------------+
+
+.. c:type:: PyMemAllocatorDomain
+
+   Enum used to identify an allocator domain. Domains:
+
+   * :c:data:`PYMEM_DOMAIN_RAW`: functions :c:func:`PyMem_RawMalloc`,
+     :c:func:`PyMem_RawRealloc` and :c:func:`PyMem_RawFree`
+   * :c:data:`PYMEM_DOMAIN_MEM`: functions :c:func:`PyMem_Malloc`,
+     :c:func:`PyMem_Realloc` and :c:func:`PyMem_Free`
+   * :c:data:`PYMEM_DOMAIN_OBJ`: functions :c:func:`PyObject_Malloc`,
+     :c:func:`PyObject_Realloc` and :c:func:`PyObject_Free`
+
+
+.. c:function:: void PyMem_GetAllocator(PyMemAllocatorDomain domain, PyMemAllocator *allocator)
+
+   Get the memory block allocator of the specified domain.
+
+
+.. c:function:: void PyMem_SetAllocator(PyMemAllocatorDomain domain, PyMemAllocator *allocator)
+
+   Set the memory block allocator of the specified domain.
+
+   The new allocator must return a distinct non-NULL pointer when requesting
+   zero bytes.
+
+   For the :c:data:`PYMEM_DOMAIN_RAW` domain, the allocator must be
+   thread-safe: the :term:`GIL <global interpreter lock>` is not held when the
+   allocator is called.
+
+   If the new allocator is not a hook (does not call the previous allocator),
+   the :c:func:`PyMem_SetupDebugHooks` function must be called to reinstall the
+   debug hooks on top on the new allocator.
+
+
+.. c:function:: void PyMem_SetupDebugHooks(void)
+
+   Setup hooks to detect bugs in the following Python memory allocator
+   functions:
+
+   - :c:func:`PyMem_RawMalloc`, :c:func:`PyMem_RawRealloc`,
+     :c:func:`PyMem_RawFree`
+   - :c:func:`PyMem_Malloc`, :c:func:`PyMem_Realloc`, :c:func:`PyMem_Free`
+   - :c:func:`PyObject_Malloc`, :c:func:`PyObject_Realloc`,
+     :c:func:`PyObject_Free`
+
+   Newly allocated memory is filled with the byte ``0xCB``, freed memory is
+   filled with the byte ``0xDB``. Additionnal checks:
+
+   - detect API violations, ex: :c:func:`PyObject_Free` called on a buffer
+     allocated by :c:func:`PyMem_Malloc`
+   - detect write before the start of the buffer (buffer underflow)
+   - detect write after the end of the buffer (buffer overflow)
+
+   The function does nothing if Python is not compiled is debug mode.
+
+
+Customize PyObject Arena Allocator
+==================================
+
+Python has a *pymalloc* allocator for allocations smaller than 512 bytes. This
+allocator is optimized for small objects with a short lifetime. It uses memory
+mappings called "arenas" with a fixed size of 256 KB. It falls back to
+:c:func:`PyMem_Malloc` and :c:func:`PyMem_Realloc` for allocations larger than
+512 bytes.  *pymalloc* is the default allocator used by
+:c:func:`PyObject_Malloc`.
+
+The default arena allocator uses the following functions:
+
+* :c:func:`VirtualAlloc` and :c:func:`VirtualFree` on Windows,
+* :c:func:`mmap` and :c:func:`munmap` if available,
+* :c:func:`malloc` and :c:func:`free` otherwise.
+
+.. versionadded:: 3.4
+
+.. c:type:: PyObjectArenaAllocator
+
+   Structure used to describe an arena allocator. The structure has
+   three fields:
+
+   +--------------------------------------------------+---------------------------------------+
+   | Field                                            | Meaning                               |
+   +==================================================+=======================================+
+   | ``void *ctx``                                    | user context passed as first argument |
+   +--------------------------------------------------+---------------------------------------+
+   | ``void* alloc(void *ctx, size_t size)``          | allocate an arena of size bytes       |
+   +--------------------------------------------------+---------------------------------------+
+   | ``void free(void *ctx, size_t size, void *ptr)`` | free an arena                         |
+   +--------------------------------------------------+---------------------------------------+
+
+.. c:function:: PyObject_GetArenaAllocator(PyObjectArenaAllocator *allocator)
+
+   Get the arena allocator.
+
+.. c:function:: PyObject_SetArenaAllocator(PyObjectArenaAllocator *allocator)
+
+   Set the arena allocator.
+
+
 .. _memoryexamples:
 
 Examples

Doc/whatsnew/3.4.rst

@@ -112,21 +112,11 @@ Security improvements:
 Please read on for a comprehensive list of user-facing changes.
 
 
-.. PEP-sized items next.
-
-.. _pep-4XX:
-
-.. PEP 4XX: Example PEP
-.. ====================
-
-
-.. (Implemented by Foo Bar.)
-
-.. .. seealso::
-
-   :pep:`4XX` - Example PEP
-      PEP written by Example Author
+PEP 445: Add new APIs to customize Python memory allocators
+===========================================================
 
+The :pep:`445` adds new Application Programming Interfaces (API) to customize
+Python memory allocators.
 
 
 

Include/objimpl.h

@@ -94,9 +94,9 @@ PyObject_{New, NewVar, Del}.
    the object gets initialized via PyObject_{Init, InitVar} after obtaining
    the raw memory.
 */
-PyAPI_FUNC(void *) PyObject_Malloc(size_t);
-PyAPI_FUNC(void *) PyObject_Realloc(void *, size_t);
-PyAPI_FUNC(void) PyObject_Free(void *);
+PyAPI_FUNC(void *) PyObject_Malloc(size_t size);
+PyAPI_FUNC(void *) PyObject_Realloc(void *ptr, size_t new_size);
+PyAPI_FUNC(void) PyObject_Free(void *ptr);
 
 /* This function returns the number of allocated memory blocks, regardless of size */
 PyAPI_FUNC(Py_ssize_t) _Py_GetAllocatedBlocks(void);
@@ -106,41 +106,15 @@ PyAPI_FUNC(Py_ssize_t) _Py_GetAllocatedBlocks(void);
 #ifndef Py_LIMITED_API
 PyAPI_FUNC(void) _PyObject_DebugMallocStats(FILE *out);
 #endif /* #ifndef Py_LIMITED_API */
-#ifdef PYMALLOC_DEBUG   /* WITH_PYMALLOC && PYMALLOC_DEBUG */
-PyAPI_FUNC(void *) _PyObject_DebugMalloc(size_t nbytes);
-PyAPI_FUNC(void *) _PyObject_DebugRealloc(void *p, size_t nbytes);
-PyAPI_FUNC(void) _PyObject_DebugFree(void *p);
-PyAPI_FUNC(void) _PyObject_DebugDumpAddress(const void *p);
-PyAPI_FUNC(void) _PyObject_DebugCheckAddress(const void *p);
-PyAPI_FUNC(void *) _PyObject_DebugMallocApi(char api, size_t nbytes);
-PyAPI_FUNC(void *) _PyObject_DebugReallocApi(char api, void *p, size_t nbytes);
-PyAPI_FUNC(void) _PyObject_DebugFreeApi(char api, void *p);
-PyAPI_FUNC(void) _PyObject_DebugCheckAddressApi(char api, const void *p);
-PyAPI_FUNC(void *) _PyMem_DebugMalloc(size_t nbytes);
-PyAPI_FUNC(void *) _PyMem_DebugRealloc(void *p, size_t nbytes);
-PyAPI_FUNC(void) _PyMem_DebugFree(void *p);
-#define PyObject_MALLOC         _PyObject_DebugMalloc
-#define PyObject_Malloc         _PyObject_DebugMalloc
-#define PyObject_REALLOC        _PyObject_DebugRealloc
-#define PyObject_Realloc        _PyObject_DebugRealloc
-#define PyObject_FREE           _PyObject_DebugFree
-#define PyObject_Free           _PyObject_DebugFree
-
-#else   /* WITH_PYMALLOC && ! PYMALLOC_DEBUG */
+#endif
+
+/* Macros */
 #define PyObject_MALLOC         PyObject_Malloc
 #define PyObject_REALLOC        PyObject_Realloc
 #define PyObject_FREE           PyObject_Free
-#endif
-
-#else   /* ! WITH_PYMALLOC */
-#define PyObject_MALLOC         PyMem_MALLOC
-#define PyObject_REALLOC        PyMem_REALLOC
-#define PyObject_FREE           PyMem_FREE
-
-#endif  /* WITH_PYMALLOC */
-
 #define PyObject_Del            PyObject_Free
-#define PyObject_DEL            PyObject_FREE
+#define PyObject_DEL            PyObject_Free
+
 
 /*
  * Generic object allocator interface
@@ -224,6 +198,26 @@ PyAPI_FUNC(PyVarObject *) _PyObject_NewVar(PyTypeObject *, Py_ssize_t);
    constructor you would start directly with PyObject_Init/InitVar
 */
 
+#ifndef Py_LIMITED_API
+typedef struct {
+    /* user context passed as the first argument to the 2 functions */
+    void *ctx;
+
+    /* allocate an arena of size bytes */
+    void* (*alloc) (void *ctx, size_t size);
+
+    /* free an arena */
+    void (*free) (void *ctx, void *ptr, size_t size);
+} PyObjectArenaAllocator;
+
+/* Get the arena allocator. */
+PyAPI_FUNC(void) PyObject_GetArenaAllocator(PyObjectArenaAllocator *allocator);
+
+/* Set the arena allocator. */
+PyAPI_FUNC(void) PyObject_SetArenaAllocator(PyObjectArenaAllocator *allocator);
+#endif
+
+
 /*
  * Garbage Collection Support
  * ==========================

Include/pymem.h

@@ -11,6 +11,11 @@
 extern "C" {
 #endif
 
+PyAPI_FUNC(void *) PyMem_RawMalloc(size_t size);
+PyAPI_FUNC(void *) PyMem_RawRealloc(void *ptr, size_t new_size);
+PyAPI_FUNC(void) PyMem_RawFree(void *ptr);
+
+
 /* BEWARE:
 
    Each interface exports both functions and macros.  Extension modules should
@@ -49,21 +54,11 @@ extern "C" {
    performed on failure (no exception is set, no warning is printed, etc).
 */
 
-PyAPI_FUNC(void *) PyMem_Malloc(size_t);
-PyAPI_FUNC(void *) PyMem_Realloc(void *, size_t);
-PyAPI_FUNC(void) PyMem_Free(void *);
-
-/* Starting from Python 1.6, the wrappers Py_{Malloc,Realloc,Free} are
-   no longer supported. They used to call PyErr_NoMemory() on failure. */
+PyAPI_FUNC(void *) PyMem_Malloc(size_t size);
+PyAPI_FUNC(void *) PyMem_Realloc(void *ptr, size_t new_size);
+PyAPI_FUNC(void) PyMem_Free(void *ptr);
 
 /* Macros. */
-#ifdef PYMALLOC_DEBUG
-/* Redirect all memory operations to Python's debugging allocator. */
-#define PyMem_MALLOC		_PyMem_DebugMalloc
-#define PyMem_REALLOC		_PyMem_DebugRealloc
-#define PyMem_FREE		_PyMem_DebugFree
-
-#else	/* ! PYMALLOC_DEBUG */
 
 /* PyMem_MALLOC(0) means malloc(1). Some systems would return NULL
    for malloc(0), which would be treated as an error. Some platforms
@@ -71,13 +66,9 @@ PyAPI_FUNC(void) PyMem_Free(void *);
    pymalloc. To solve these problems, allocate an extra byte. */
 /* Returns NULL to indicate error if a negative size or size larger than
    Py_ssize_t can represent is supplied.  Helps prevents security holes. */
-#define PyMem_MALLOC(n)		((size_t)(n) > (size_t)PY_SSIZE_T_MAX ? NULL \
-				: malloc((n) ? (n) : 1))
-#define PyMem_REALLOC(p, n)	((size_t)(n) > (size_t)PY_SSIZE_T_MAX  ? NULL \
-				: realloc((p), (n) ? (n) : 1))
-#define PyMem_FREE		free
-
-#endif	/* PYMALLOC_DEBUG */
+#define PyMem_MALLOC(n)         PyMem_Malloc(n)
+#define PyMem_REALLOC(p, n)     PyMem_Realloc(p, n)
+#define PyMem_FREE(p)           PyMem_Free(p)
 
 /*
  * Type-oriented memory interface
@@ -115,6 +106,69 @@ PyAPI_FUNC(void) PyMem_Free(void *);
 #define PyMem_Del		PyMem_Free
 #define PyMem_DEL		PyMem_FREE
 
+#ifndef Py_LIMITED_API
+typedef enum {
+    /* PyMem_RawMalloc(), PyMem_RawRealloc() and PyMem_RawFree() */
+    PYMEM_DOMAIN_RAW,
+
+    /* PyMem_Malloc(), PyMem_Realloc() and PyMem_Free() */
+    PYMEM_DOMAIN_MEM,
+
+    /* PyObject_Malloc(), PyObject_Realloc() and PyObject_Free() */
+    PYMEM_DOMAIN_OBJ
+} PyMemAllocatorDomain;
+
+typedef struct {
+    /* user context passed as the first argument to the 3 functions */
+    void *ctx;
+
+    /* allocate a memory block */
+    void* (*malloc) (void *ctx, size_t size);
+
+    /* allocate or resize a memory block */
+    void* (*realloc) (void *ctx, void *ptr, size_t new_size);
+
+    /* release a memory block */
+    void (*free) (void *ctx, void *ptr);
+} PyMemAllocator;
+
+/* Get the memory block allocator of the specified domain. */
+PyAPI_FUNC(void) PyMem_GetAllocator(PyMemAllocatorDomain domain,
+                                    PyMemAllocator *allocator);
+
+/* Set the memory block allocator of the specified domain.
+
+   The new allocator must return a distinct non-NULL pointer when requesting
+   zero bytes.
+
+   For the PYMEM_DOMAIN_RAW domain, the allocator must be thread-safe: the GIL
+   is not held when the allocator is called.
+
+   If the new allocator is not a hook (don't call the previous allocator), the
+   PyMem_SetupDebugHooks() function must be called to reinstall the debug hooks
+   on top on the new allocator. */
+PyAPI_FUNC(void) PyMem_SetAllocator(PyMemAllocatorDomain domain,
+                                    PyMemAllocator *allocator);
+
+/* Setup hooks to detect bugs in the following Python memory allocator
+   functions:
+
+   - PyMem_RawMalloc(), PyMem_RawRealloc(), PyMem_RawFree()
+   - PyMem_Malloc(), PyMem_Realloc(), PyMem_Free()
+   - PyObject_Malloc(), PyObject_Realloc() and PyObject_Free()
+
+   Newly allocated memory is filled with the byte 0xCB, freed memory is filled
+   with the byte 0xDB. Additionnal checks:
+
+   - detect API violations, ex: PyObject_Free() called on a buffer allocated
+     by PyMem_Malloc()
+   - detect write before the start of the buffer (buffer underflow)
+   - detect write after the end of the buffer (buffer overflow)
+
+   The function does nothing if Python is not compiled is debug mode. */
+PyAPI_FUNC(void) PyMem_SetupDebugHooks(void);
+#endif
+
 #ifdef __cplusplus
 }
 #endif

Misc/NEWS

@@ -10,6 +10,9 @@ What's New in Python 3.4.0 Alpha 1?
 Core and Builtins
 -----------------
 
+- Issue #3329: Implement the PEP 445: Add new APIs to customize Python memory
+  allocators.
+
 - Issue #18328: Reorder ops in PyThreadState_Delete*() functions. Now the
   tstate is first removed from TLS and then deallocated.
 

Modules/_testcapimodule.c

@@ -2511,6 +2511,161 @@ test_decref_doesnt_leak(PyObject *ob)
     Py_RETURN_NONE;
 }
 
+static PyObject *
+test_pymem_alloc0(PyObject *self)
+{
+    void *ptr;
+
+    ptr = PyMem_Malloc(0);
+    if (ptr == NULL) {
+        PyErr_SetString(PyExc_RuntimeError, "PyMem_Malloc(0) returns NULL");
+        return NULL;
+    }
+    PyMem_Free(ptr);
+
+    ptr = PyObject_Malloc(0);
+    if (ptr == NULL) {
+        PyErr_SetString(PyExc_RuntimeError, "PyObject_Malloc(0) returns NULL");
+        return NULL;
+    }
+    PyObject_Free(ptr);
+
+    Py_RETURN_NONE;
+}
+
+typedef struct {
+    PyMemAllocator alloc;
+
+    size_t malloc_size;
+    void *realloc_ptr;
+    size_t realloc_new_size;
+    void *free_ptr;
+} alloc_hook_t;
+
+static void* hook_malloc (void* ctx, size_t size)
+{
+    alloc_hook_t *hook = (alloc_hook_t *)ctx;
+    hook->malloc_size = size;
+    return hook->alloc.malloc(hook->alloc.ctx, size);
+}
+
+static void* hook_realloc (void* ctx, void* ptr, size_t new_size)
+{
+    alloc_hook_t *hook = (alloc_hook_t *)ctx;
+    hook->realloc_ptr = ptr;
+    hook->realloc_new_size = new_size;
+    return hook->alloc.realloc(hook->alloc.ctx, ptr, new_size);
+}
+
+static void hook_free (void *ctx, void *ptr)
+{
+    alloc_hook_t *hook = (alloc_hook_t *)ctx;
+    hook->free_ptr = ptr;
+    hook->alloc.free(hook->alloc.ctx, ptr);
+}
+
+static PyObject *
+test_setallocators(PyMemAllocatorDomain domain)
+{
+    PyObject *res = NULL;
+    const char *error_msg;
+    alloc_hook_t hook;
+    PyMemAllocator alloc;
+    size_t size, size2;
+    void *ptr, *ptr2;
+
+    hook.malloc_size = 0;
+    hook.realloc_ptr = NULL;
+    hook.realloc_new_size = 0;
+    hook.free_ptr = NULL;
+
+    alloc.ctx = &hook;
+    alloc.malloc = &hook_malloc;
+    alloc.realloc = &hook_realloc;
+    alloc.free = &hook_free;
+    PyMem_GetAllocator(domain, &hook.alloc);
+    PyMem_SetAllocator(domain, &alloc);
+
+    size = 42;
+    switch(domain)
+    {
+    case PYMEM_DOMAIN_RAW: ptr = PyMem_RawMalloc(size); break;
+    case PYMEM_DOMAIN_MEM: ptr = PyMem_Malloc(size); break;
+    case PYMEM_DOMAIN_OBJ: ptr = PyObject_Malloc(size); break;
+    default: ptr = NULL; break;
+    }
+
+    if (ptr == NULL) {
+        error_msg = "malloc failed";
+        goto fail;
+    }
+
+    if (hook.malloc_size != size) {
+        error_msg = "malloc invalid size";
+        goto fail;
+    }
+
+    size2 = 200;
+    switch(domain)
+    {
+    case PYMEM_DOMAIN_RAW: ptr2 = PyMem_RawRealloc(ptr, size2); break;
+    case PYMEM_DOMAIN_MEM: ptr2 = PyMem_Realloc(ptr, size2); break;
+    case PYMEM_DOMAIN_OBJ: ptr2 = PyObject_Realloc(ptr, size2); break;
+    }
+
+    if (ptr2 == NULL) {
+        error_msg = "realloc failed";
+        goto fail;
+    }
+
+    if (hook.realloc_ptr != ptr
+        || hook.realloc_new_size != size2) {
+        error_msg = "realloc invalid parameters";
+        goto fail;
+    }
+
+    switch(domain)
+    {
+    case PYMEM_DOMAIN_RAW: PyMem_RawFree(ptr2); break;
+    case PYMEM_DOMAIN_MEM: PyMem_Free(ptr2); break;
+    case PYMEM_DOMAIN_OBJ: PyObject_Free(ptr2); break;
+    }
+
+    if (hook.free_ptr != ptr2) {
+        error_msg = "free invalid pointer";
+        goto fail;
+    }
+
+    Py_INCREF(Py_None);
+    res = Py_None;
+    goto finally;
+
+fail:
+    PyErr_SetString(PyExc_RuntimeError, error_msg);
+
+finally:
+    PyMem_SetAllocator(domain, &hook.alloc);
+    return res;
+}
+
+static PyObject *
+test_pymem_setrawallocators(PyObject *self)
+{
+    return test_setallocators(PYMEM_DOMAIN_RAW);
+}
+
+static PyObject *
+test_pymem_setallocators(PyObject *self)
+{
+    return test_setallocators(PYMEM_DOMAIN_MEM);
+}
+
+static PyObject *
+test_pyobject_setallocators(PyObject *self)
+{
+    return test_setallocators(PYMEM_DOMAIN_OBJ);
+}
+
 static PyMethodDef TestMethods[] = {
     {"raise_exception",         raise_exception,                 METH_VARARGS},
     {"raise_memoryerror",   (PyCFunction)raise_memoryerror,  METH_NOARGS},
@@ -2611,6 +2766,14 @@ static PyMethodDef TestMethods[] = {
     {"pytime_object_to_time_t", test_pytime_object_to_time_t,  METH_VARARGS},
     {"pytime_object_to_timeval", test_pytime_object_to_timeval,  METH_VARARGS},
     {"pytime_object_to_timespec", test_pytime_object_to_timespec,  METH_VARARGS},
+    {"test_pymem",
+     (PyCFunction)test_pymem_alloc0, METH_NOARGS},
+    {"test_pymem_alloc0",
+     (PyCFunction)test_pymem_setrawallocators, METH_NOARGS},
+    {"test_pymem_setallocators",
+     (PyCFunction)test_pymem_setallocators, METH_NOARGS},
+    {"test_pyobject_setallocators",
+     (PyCFunction)test_pyobject_setallocators, METH_NOARGS},
     {NULL, NULL} /* sentinel */
 };
 

Objects/object.c

@@ -1859,26 +1859,6 @@ PyTypeObject *_PyCapsule_hack = &PyCapsule_Type;
 Py_ssize_t (*_Py_abstract_hack)(PyObject *) = PyObject_Size;
 
 
-/* Python's malloc wrappers (see pymem.h) */
-
-void *
-PyMem_Malloc(size_t nbytes)
-{
-    return PyMem_MALLOC(nbytes);
-}
-
-void *
-PyMem_Realloc(void *p, size_t nbytes)
-{
-    return PyMem_REALLOC(p, nbytes);
-}
-
-void
-PyMem_Free(void *p)
-{
-    PyMem_FREE(p);
-}
-
 void
 _PyObject_DebugTypeStats(FILE *out)
 {