GH-148726: Add heap_size to generational GC (#149195)

Modules/_remote_debugging/clinic/module.c.h

@@ -601,6 +601,7 @@ PyDoc_STRVAR(_remote_debugging_GCMonitor_get_gc_stats__doc__,
 "        - collected: Total number of collected objects.\n"
 "        - uncollectable: Total number of uncollectable objects.\n"
 "        - candidates: Total objects considered and traversed.\n"
+"        - heap_size: number of live objects.\n"
 "        - duration: Total collection time, in seconds.\n"
 "\n"
 "Raises:\n"
@@ -1563,4 +1564,4 @@ skip_optional_kwonly:
 exit:
     return return_value;
 }
-/*[clinic end generated code: output=1151e58683dab9f4 input=a9049054013a1b77]*/
+/*[clinic end generated code: output=36674f4cb8a653f3 input=a9049054013a1b77]*/

Modules/_remote_debugging/gc_stats.c

@@ -53,6 +53,7 @@ read_gc_stats(struct gc_stats *stats, int64_t iid, PyObject *result,
             SET_FIELD(PyLong_FromSsize_t, items->collected);
             SET_FIELD(PyLong_FromSsize_t, items->uncollectable);
             SET_FIELD(PyLong_FromSsize_t, items->candidates);
+            SET_FIELD(PyLong_FromSsize_t, items->heap_size);
 
             SET_FIELD(PyFloat_FromDouble, items->duration);
 

Modules/_remote_debugging/module.c

@@ -143,6 +143,7 @@ static PyStructSequence_Field GCStatsInfo_fields[] = {
     {"collected", "Total number of collected objects"},
     {"uncollectable", "Total number of uncollectable objects"},
     {"candidates", "Total objects considered and traversed"},
+    {"heap_size", "Number of live objects"},
     {"duration", "Total collection time, in seconds"},
     {NULL}
 };
@@ -151,7 +152,7 @@ PyStructSequence_Desc GCStatsInfo_desc = {
     "_remote_debugging.GCStatsInfo",
     "Information about a garbage collector stats sample",
     GCStatsInfo_fields,
-    9
+    10
 };
 
 /* ============================================================================
@@ -1225,6 +1226,7 @@ Returns:
         - collected: Total number of collected objects.
         - uncollectable: Total number of uncollectable objects.
         - candidates: Total objects considered and traversed.
+        - heap_size: number of live objects.
         - duration: Total collection time, in seconds.
 
 Raises:
@@ -1235,7 +1237,7 @@ Raises:
 static PyObject *
 _remote_debugging_GCMonitor_get_gc_stats_impl(GCMonitorObject *self,
                                               int all_interpreters)
-/*[clinic end generated code: output=f73f365725224f7a input=09e647719c65f9e4]*/
+/*[clinic end generated code: output=f73f365725224f7a input=12f7c1a288cf2741]*/
 {
     RemoteDebuggingState *st = RemoteDebugging_GetStateFromType(Py_TYPE(self));
     return get_gc_stats(&self->offsets, all_interpreters, st->GCStatsInfo_Type);

Modules/_testinternalcapi.c

@@ -2731,8 +2731,7 @@ has_deferred_refcount(PyObject *self, PyObject *op)
 static PyObject *
 get_tracked_heap_size(PyObject *self, PyObject *Py_UNUSED(ignored))
 {
-    // Generational GC doesn't track heap_size, return -1.
-    return PyLong_FromInt64(-1);
+    return PyLong_FromInt64(PyInterpreterState_Get()->gc.heap_size);
 }
 
 static PyObject *