bpo-44895: Introduce PYTHONDUMPREFSFILE variable for refcount dumping

Doc/using/cmdline.rst

@@ -975,3 +975,12 @@ Debug-mode variables
    shutting down the interpreter.
 
    Need Python configured with the :option:`--with-trace-refs` build option.
+
+.. envvar:: PYTHONDUMPFILE
+
+   If set, Python will create a file named `$PYTHONDUMPFILE` as the dump file
+   which is generated by :envvar:`PYTHONDUMPREFS`.
+
+   Need Python configured with the :option:`--with-trace-refs` build option.
+
+   .. versionadded:: 3.11

Include/cpython/initconfig.h

@@ -144,6 +144,7 @@ typedef struct PyConfig {
     int show_ref_count;
     int dump_refs;
     int malloc_stats;
+    wchar_t *python_dump_file;
     wchar_t *filesystem_encoding;
     wchar_t *filesystem_errors;
     wchar_t *pycache_prefix;

Misc/NEWS.d/next/Core and Builtins/2021-08-14-20-13-21.bpo-44895.Ic9m90.rst

@@ -0,0 +1,2 @@
+A debug variable :envvar:`PYTHONDUMPFILE` is added for creating a dump file
+which is generated by :envvar:`PYTHONDUMPREFS`. Patch by Dong-hee Na.

Python/initconfig.c

@@ -898,6 +898,7 @@ _PyConfig_Copy(PyConfig *config, const PyConfig *config2)
     COPY_ATTR(no_debug_ranges);
     COPY_ATTR(show_ref_count);
     COPY_ATTR(dump_refs);
+    COPY_ATTR(python_dump_file);
     COPY_ATTR(malloc_stats);
 
     COPY_WSTR_ATTR(pycache_prefix);
@@ -1701,6 +1702,14 @@ config_read_env_vars(PyConfig *config)
         config->malloc_stats = 1;
     }
 
+    if (config->python_dump_file == NULL) {
+        status = CONFIG_GET_ENV_DUP(config, &config->python_dump_file,
+                                    L"PYTHONDUMPFILE", "PYTHONDUMPFILE");
+        if (_PyStatus_EXCEPTION(status)) {
+            return status;
+        }
+    }
+
     if (config->pythonpath_env == NULL) {
         status = CONFIG_GET_ENV_DUP(config, &config->pythonpath_env,
                                     L"PYTHONPATH", "PYTHONPATH");

Python/pylifecycle.c

@@ -1736,6 +1736,7 @@ Py_FinalizeEx(void)
     int show_ref_count = tstate->interp->config.show_ref_count;
 #endif
 #ifdef Py_TRACE_REFS
+    wchar_t *python_dump_file = tstate->interp->config.python_dump_file;
     int dump_refs = tstate->interp->config.dump_refs;
 #endif
 #ifdef WITH_PYMALLOC
@@ -1835,8 +1836,13 @@ Py_FinalizeEx(void)
      * Alas, a lot of stuff may still be alive now that will be cleaned
      * up later.
      */
+
+    FILE *fp = stderr;
+    if (python_dump_file != NULL) {
+        fp = _Py_wfopen(python_dump_file, L"w");
+    }
     if (dump_refs) {
-        _Py_PrintReferences(stderr);
+        _Py_PrintReferences(fp);
     }
 #endif /* Py_TRACE_REFS */
 
@@ -1849,7 +1855,10 @@ Py_FinalizeEx(void)
      * above by _Py_PrintReferences.
      */
     if (dump_refs) {
-        _Py_PrintReferenceAddresses(stderr);
+        _Py_PrintReferenceAddresses(fp);
+    }
+    if (fp != NULL && fp != stderr) {
+        fclose(fp);
     }
 #endif /* Py_TRACE_REFS */
 #ifdef WITH_PYMALLOC