gh-154032: Scale elided flamegraph values

Author: pablogsal

Lib/profiling/sampling/stack_collector.py

@@ -764,6 +764,7 @@ def _build_elided_flamegraph(self, baseline_stats, scale):
         if not self._extract_elided_nodes(baseline_data, path=()):
             return None
 
+        self._scale_flamegraph_values(baseline_data, scale)
         self._add_elided_metadata(baseline_data, baseline_stats, scale, path=())
 
         # Merge only profiling metadata, not thread-level stats
@@ -777,6 +778,13 @@ def _build_elided_flamegraph(self, baseline_stats, scale):
 
         return baseline_data
 
+    def _scale_flamegraph_values(self, node, scale):
+        """Express flamegraph values in units of the current sample interval."""
+        node["value"] = node.get("value", 0) * scale
+        node["self"] = node.get("self", 0) * scale
+        for child in node.get("children", ()):
+            self._scale_flamegraph_values(child, scale)
+
     def _extract_elided_nodes(self, node, path):
         """Remove non-elided nodes and recalculate values bottom-up."""
         if not node:

Lib/test/test_profiling/test_sampling_profiler/test_collectors.py

@@ -1663,6 +1663,33 @@ def test_diff_flamegraph_scale_factor_uses_sample_intervals(self):
         self.assertAlmostEqual(data["diff"], 0.0)
         self.assertAlmostEqual(data["diff_pct"], 0.0)
 
+    def test_diff_flamegraph_elided_values_use_current_interval(self):
+        """Elided geometry and metadata use the same sample units."""
+        baseline_frames = [
+            MockInterpreterInfo(0, [
+                MockThreadInfo(1, [MockFrameInfo("file.py", 10, "old_func")])
+            ])
+        ]
+        current_frames = [
+            MockInterpreterInfo(0, [
+                MockThreadInfo(1, [MockFrameInfo("file.py", 20, "new_func")])
+            ])
+        ]
+
+        diff = make_diff_collector_with_mock_baseline(
+            [baseline_frames] * 10,
+            baseline_interval=1000,
+            current_interval=10000,
+        )
+        diff.collect(current_frames)
+
+        data = diff._convert_to_flamegraph_format()
+        elided = data["stats"]["elided_flamegraph"]
+        self.assertAlmostEqual(elided["value"], 1.0)
+        self.assertAlmostEqual(elided["self"], 1.0)
+        self.assertAlmostEqual(elided["baseline"], 1.0)
+        self.assertAlmostEqual(elided["diff"], -1.0)
+
     def test_diff_flamegraph_elided_stacks(self):
         """Paths in baseline but not current produce elided stacks."""
         baseline_frames_1 = [