bpo-32030: Rework memory allocators (#4625)

* Fix _PyMem_SetupAllocators("debug"): always restore allocators to
  the defaults, rather than only caling _PyMem_SetupDebugHooks().
* Add _PyMem_SetDefaultAllocator() helper to set the "default"
  allocator.
* Add _PyMem_GetAllocatorsName(): get the name of the allocators
* main() now uses debug hooks on memory allocators if Py_DEBUG is
  defined, rather than calling directly malloc()
* Document default memory allocators in C API documentation
* _Py_InitializeCore() now fails with a fatal user error if
  PYTHONMALLOC value is an unknown memory allocator, instead of
  failing with a fatal internal error.
* Add new tests on the PYTHONMALLOC environment variable
* Add support.with_pymalloc()
* Add the _testcapi.WITH_PYMALLOC constant and expose it as
   support.with_pymalloc().
* sysconfig.get_config_var('WITH_PYMALLOC') doesn't work on Windows, so
   replace it with support.with_pymalloc().
* pythoninfo: add _testcapi collector for pymem

1 files changed, 7 insertions, 12 deletions

diff --git a/Modules/main.c b/Modules/main.c
index 899cbc2..ec33b5f 100644
--- a/Modules/main.c
+++ b/Modules/main.c
@@ -475,11 +475,9 @@ pymain_free_impl(_PyMain *pymain)
 static void
 pymain_free(_PyMain *pymain)
 {
-    /* Force malloc() memory allocator */
-    PyMemAllocatorEx old_alloc, raw_alloc;
-    PyMem_GetAllocator(PYMEM_DOMAIN_RAW, &old_alloc);
-    _PyMem_GetDefaultRawAllocator(&raw_alloc);
-    PyMem_SetAllocator(PYMEM_DOMAIN_RAW, &raw_alloc);
+    /* Force the allocator used by pymain_parse_cmdline_envvars() */
+    PyMemAllocatorEx old_alloc;
+    _PyMem_SetDefaultAllocator(PYMEM_DOMAIN_RAW, &old_alloc);
 
     pymain_free_impl(pymain);
 
@@ -1561,17 +1559,14 @@ pymain_parse_cmdline_envvars_impl(_PyMain *pymain)
 static int
 pymain_parse_cmdline_envvars(_PyMain *pymain)
 {
-    /* Force malloc() memory allocator */
-    PyMemAllocatorEx old_alloc, raw_alloc;
-    PyMem_GetAllocator(PYMEM_DOMAIN_RAW, &old_alloc);
-    _PyMem_GetDefaultRawAllocator(&raw_alloc);
-    PyMem_SetAllocator(PYMEM_DOMAIN_RAW, &raw_alloc);
+    /* Force default allocator, since pymain_free() must use the same allocator
+       than this function. */
+    PyMemAllocatorEx old_alloc;
+    _PyMem_SetDefaultAllocator(PYMEM_DOMAIN_RAW, &old_alloc);
 
     int res = pymain_parse_cmdline_envvars_impl(pymain);
 
-    /* Restore the old memory allocator */
     PyMem_SetAllocator(PYMEM_DOMAIN_RAW, &old_alloc);
-
     return res;
 }