bpo-32030: Add pymain_get_global_config() (#4735)

* Py_Main() now starts by reading Py_xxx configuration variables to
  only work on its own private structure, and then later writes back
  the configuration into these variables.
* Replace Py_GETENV() with pymain_get_env_var() which ignores empty
  variables.
* Add _PyCoreConfig.dump_refs
* Add _PyCoreConfig.malloc_stats
* _PyObject_DebugMallocStats() is now responsible to check if debug
  hooks are installed. The function returns 1 if stats were written,
  or 0 if the hooks are disabled. Mark _PyMem_PymallocEnabled() as
  static.

Include/objimpl.h

@@ -109,7 +109,7 @@ PyAPI_FUNC(Py_ssize_t) _Py_GetAllocatedBlocks(void);
 /* Macros */
 #ifdef WITH_PYMALLOC
 #ifndef Py_LIMITED_API
-PyAPI_FUNC(void) _PyObject_DebugMallocStats(FILE *out);
+PyAPI_FUNC(int) _PyObject_DebugMallocStats(FILE *out);
 #endif /* #ifndef Py_LIMITED_API */
 #endif
 

Include/pymem.h

@@ -24,10 +24,6 @@ PyAPI_FUNC(int) _PyMem_SetupAllocators(const char *opt);
 /* Try to get the allocators name set by _PyMem_SetupAllocators(). */
 PyAPI_FUNC(const char*) _PyMem_GetAllocatorsName(void);
 
-#ifdef WITH_PYMALLOC
-PyAPI_FUNC(int) _PyMem_PymallocEnabled(void);
-#endif
-
 /* Track an allocated memory block in the tracemalloc module.
    Return 0 on success, return -1 on error (failed to allocate memory to store
    the trace).

Include/pystate.h

@@ -36,6 +36,8 @@ typedef struct {
     int import_time;        /* -X importtime */
     int show_ref_count;     /* -X showrefcount */
     int show_alloc_count;   /* -X showalloccount */
+    int dump_refs;          /* PYTHONDUMPREFS */
+    int malloc_stats;       /* PYTHONMALLOCSTATS */
 } _PyCoreConfig;
 
 #define _PyCoreConfig_INIT (_PyCoreConfig){.use_hash_seed = -1}
@@ -111,7 +113,7 @@ typedef struct _is {
     PyObject *after_forkers_child;
 #endif
 } PyInterpreterState;
-#endif
+#endif   /* !Py_LIMITED_API */
 
 
 /* State unique per thread */
@@ -133,7 +135,7 @@ typedef int (*Py_tracefunc)(PyObject *, struct _frame *, int, PyObject *);
 #define PyTrace_C_EXCEPTION 5
 #define PyTrace_C_RETURN 6
 #define PyTrace_OPCODE 7
-#endif
+#endif   /* Py_LIMITED_API */
 
 #ifdef Py_LIMITED_API
 typedef struct _ts PyThreadState;
@@ -238,7 +240,7 @@ typedef struct _ts {
     /* XXX signal handlers should also be here */
 
 } PyThreadState;
-#endif
+#endif   /* !Py_LIMITED_API */
 
 
 PyAPI_FUNC(PyInterpreterState *) PyInterpreterState_New(void);
@@ -363,7 +365,7 @@ PyAPI_FUNC(int) PyGILState_Check(void);
    Return NULL before _PyGILState_Init() is called and after _PyGILState_Fini()
    is called. */
 PyAPI_FUNC(PyInterpreterState *) _PyGILState_GetInterpreterStateUnsafe(void);
-#endif
+#endif   /* !Py_LIMITED_API */
 
 
 /* The implementation of sys._current_frames()  Returns a dict mapping

Objects/obmalloc.c

@@ -379,7 +379,7 @@ _PyMem_DebugEnabled(void)
     return (_PyObject.malloc == _PyMem_DebugMalloc);
 }
 
-int
+static int
 _PyMem_PymallocEnabled(void)
 {
     if (_PyMem_DebugEnabled()) {
@@ -2467,10 +2467,17 @@ pool_is_in_list(const poolp target, poolp list)
 /* Print summary info to "out" about the state of pymalloc's structures.
  * In Py_DEBUG mode, also perform some expensive internal consistency
  * checks.
+ *
+ * Return 0 if the memory debug hooks are not installed or no statistics was
+ * writen into out, return 1 otherwise.
  */
-void
+int
 _PyObject_DebugMallocStats(FILE *out)
 {
+    if (!_PyMem_PymallocEnabled()) {
+        return 0;
+    }
+
     uint i;
     const uint numclasses = SMALL_REQUEST_THRESHOLD >> ALIGNMENT_SHIFT;
     /* # of pools, allocated blocks, and free blocks per class index */
@@ -2603,6 +2610,7 @@ _PyObject_DebugMallocStats(FILE *out)
     total += printone(out, "# bytes lost to quantization", quantization);
     total += printone(out, "# bytes lost to arena alignment", arena_alignment);
     (void)printone(out, "Total", total);
+    return 1;
 }
 
 #endif /* #ifdef WITH_PYMALLOC */

Python/pylifecycle.c

@@ -1103,6 +1103,10 @@ Py_FinalizeEx(void)
     tstate = PyThreadState_GET();
     interp = tstate->interp;
 
+    /* Copy the core config to be able to use it even
+       after PyInterpreterState_Delete() */
+    _PyCoreConfig core_config = interp->core_config;
+
     /* Remaining threads (e.g. daemon threads) will automatically exit
        after taking the GIL (in PyEval_RestoreThread()). */
     _PyRuntime.finalizing = tstate;
@@ -1186,7 +1190,7 @@ Py_FinalizeEx(void)
     _PyHash_Fini();
 
 #ifdef Py_REF_DEBUG
-    if (interp->core_config.show_ref_count) {
+    if (core_config.show_ref_count) {
         _PyDebug_PrintTotalRefs();
     }
 #endif
@@ -1197,8 +1201,9 @@ Py_FinalizeEx(void)
      * Alas, a lot of stuff may still be alive now that will be cleaned
      * up later.
      */
-    if (Py_GETENV("PYTHONDUMPREFS"))
+    if (core_config.dump_refs) {
         _Py_PrintReferences(stderr);
+    }
 #endif /* Py_TRACE_REFS */
 
     /* Clear interpreter state and all thread states. */
@@ -1260,14 +1265,13 @@ Py_FinalizeEx(void)
      * An address can be used to find the repr of the object, printed
      * above by _Py_PrintReferences.
      */
-    if (Py_GETENV("PYTHONDUMPREFS"))
+    if (core_config.dump_refs) {
         _Py_PrintReferenceAddresses(stderr);
+    }
 #endif /* Py_TRACE_REFS */
 #ifdef WITH_PYMALLOC
-    if (_PyMem_PymallocEnabled()) {
-        char *opt = Py_GETENV("PYTHONMALLOCSTATS");
-        if (opt != NULL && *opt != '\0')
-            _PyObject_DebugMallocStats(stderr);
+    if (core_config.malloc_stats) {
+        _PyObject_DebugMallocStats(stderr);
     }
 #endif
 

Python/sysmodule.c

@@ -1368,8 +1368,7 @@ static PyObject *
 sys_debugmallocstats(PyObject *self, PyObject *args)
 {
 #ifdef WITH_PYMALLOC
-    if (_PyMem_PymallocEnabled()) {
-        _PyObject_DebugMallocStats(stderr);
+    if (_PyObject_DebugMallocStats(stderr)) {
         fputc('\n', stderr);
     }
 #endif