fix(profiling): fix allocation metrics (#2839) (#2860)

* fix(profiling): fix allocated space estimates

The proposed fix adjusts the estimated allocated space by normalising by
the capture rate.

* update tests

Co-authored-by: mergify[bot] <37929162+mergify[bot]@users.noreply.github.com>
Co-authored-by: Brett Langdon <[email protected]>
(cherry picked from commit 2b23499)

Co-authored-by: Gabriele N. Tornetta <[email protected]>

Author: mergify[bot]

ddtrace/profiling/exporter/pprof.pyx

@@ -181,14 +181,10 @@ class _PprofConverter(object):
             ),
         )
 
-        nevents = len(events)
-        sampling_ratio_avg = sum(event.capture_pct for event in events) / nevents / 100.0
-        total_alloc = sum(event.nevents for event in events)
-        number_of_alloc = total_alloc * sampling_ratio_avg
-        average_alloc_size = sum(event.size for event in events) / float(nevents)
-
-        self._location_values[location_key]["alloc-samples"] = nevents
-        self._location_values[location_key]["alloc-space"] = round(number_of_alloc * average_alloc_size)
+        self._location_values[location_key]["alloc-samples"] = sum(event.nevents for event in events)
+        self._location_values[location_key]["alloc-space"] = round(
+            sum(event.size / event.capture_pct * 100.0 for event in events)
+        )
 
     def convert_memalloc_heap_event(self, event):
         location_key = (

releasenotes/notes/fix-profiler-allocation-metrics-96b88193d7810065.yaml

@@ -0,0 +1,5 @@
+---
+fixes:
+  - |
+    Fix the reporting of the allocated memory and the number of allocations in
+    the profiler.

tests/profiling/exporter/test-pprof-exporter.txt

@@ -152,8 +152,8 @@ sample {
   value: 0
   value: 0
   value: 0
-  value: 2
-  value: 59689
+  value: 3072
+  value: 104
   value: 58
   label {
     key: 22
@@ -402,8 +402,8 @@ sample {
   value: 0
   value: 0
   value: 0
-  value: 1
-  value: 174080
+  value: 1024
+  value: 680
   value: 340
   label {
     key: 22
@@ -564,8 +564,8 @@ sample {
   value: 0
   value: 0
   value: 0
-  value: 1
-  value: 69632
+  value: 2048
+  value: 136
   value: 68
   label {
     key: 22
@@ -726,8 +726,8 @@ sample {
   value: 0
   value: 0
   value: 0
-  value: 1
-  value: 14868
+  value: 1024
+  value: 133
   value: 44
   label {
     key: 22
@@ -933,8 +933,8 @@ sample {
   value: 0
   value: 0
   value: 0
-  value: 1
-  value: 101376
+  value: 1024
+  value: 99
   value: 99
   label {
     key: 22
@@ -1094,8 +1094,8 @@ sample {
   value: 0
   value: 0
   value: 0
-  value: 1
-  value: 24576
+  value: 2048
+  value: 12
   value: 12
   label {
     key: 22

tests/profiling/exporter/test_pprof.py

@@ -687,7 +687,7 @@ def test_to_str_none():
 
 
 @mock.patch("ddtrace.utils.config.get_application_name")
-def test_ppprof_exporter(gan):
+def test_pprof_exporter(gan):
     gan.return_value = "bonjour"
     exp = pprof.PprofExporter()
     exports = exp.export(TEST_EVENTS, 1, 7)