Add PYTHONMALLOC env var

Issue #26516:

* Add PYTHONMALLOC environment variable to set the Python memory
  allocators and/or install debug hooks.
* PyMem_SetupDebugHooks() can now also be used on Python compiled in release
  mode.
* The PYTHONMALLOCSTATS environment variable can now also be used on Python
  compiled in release mode. It now has no effect if set to an empty string.
* In debug mode, debug hooks are now also installed on Python memory allocators
  when Python is configured without pymalloc.

1 files changed, 4 insertions, 2 deletions

diff --git a/Python/sysmodule.c b/Python/sysmodule.c
index 702e8f0f9f..c5b4ac1ae9 100644
--- a/Python/sysmodule.c
+++ b/Python/sysmodule.c
@@ -1151,8 +1151,10 @@ static PyObject *
 sys_debugmallocstats(PyObject *self, PyObject *args)
 {
 #ifdef WITH_PYMALLOC
-    _PyObject_DebugMallocStats(stderr);
-    fputc('\n', stderr);
+    if (_PyMem_PymallocEnabled()) {
+        _PyObject_DebugMallocStats(stderr);
+        fputc('\n', stderr);
+    }
 #endif
     _PyObject_DebugTypeStats(stderr);