add gc_count metrics with correct collection unit .

fixes #3549

Author: david-gang

CHANGELOG.md

@@ -25,11 +25,11 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
   ([#3601](https://github.com/open-telemetry/opentelemetry-python-contrib/pull/3601))
 
 ### Fixed
-
 - `opentelemetry-instrumentation-asgi`: fix excluded_urls in instrumentation-asgi
   ([#3567](https://github.com/open-telemetry/opentelemetry-python-contrib/pull/3567))
 - `opentelemetry-resource-detector-containerid`: make it more quiet on platforms without cgroups
   ([#3579](https://github.com/open-telemetry/opentelemetry-python-contrib/pull/3579))
+- `opentelemetry-instrumentation-system-metrics`: Add process.runtime.cpython.gc_count metrics with collection unit is specified in semconv ([3617](https://github.com/open-telemetry/opentelemetry-python-contrib/pull/3617))
 
 ## Version 1.34.0/0.55b0 (2025-06-04)
 

instrumentation/opentelemetry-instrumentation-system-metrics/src/opentelemetry/instrumentation/system_metrics/__init__.py

@@ -196,6 +196,7 @@ def __init__(
         self._runtime_memory_labels = self._labels.copy()
         self._runtime_cpu_time_labels = self._labels.copy()
         self._runtime_gc_count_labels = self._labels.copy()
+        self._runtime_gc_collections_labels = self._labels.copy()
         self._runtime_thread_count_labels = self._labels.copy()
         self._runtime_cpu_utilization_labels = self._labels.copy()
         self._runtime_context_switches_labels = self._labels.copy()
@@ -469,6 +470,12 @@ def _instrument(self, **kwargs: Any):
                     description=f"Runtime {self._python_implementation} GC count",
                     unit="By",
                 )
+                self._meter.create_observable_counter(
+                    name=f"process.runtime.{self._python_implementation}.gc_count",
+                    callbacks=[self._get_runtime_gc_collections],
+                    description="The number of times a generation was collected since interpreter start.",
+                    unit="{collection}",
+                )
 
         if "process.runtime.thread_count" in self._config:
             self._meter.create_observable_up_down_counter(
@@ -885,6 +892,16 @@ def _get_runtime_gc_count(
             self._runtime_gc_count_labels["count"] = str(index)
             yield Observation(count, self._runtime_gc_count_labels.copy())
 
+    def _get_runtime_gc_collections(
+        self, options: CallbackOptions
+    ) -> Iterable[Observation]:
+        """Observer callback for garbage collection"""
+        for index, count in enumerate(gc.get_count()):
+            self._runtime_gc_collections_labels["generation"] = str(index)
+            yield Observation(
+                count, self._runtime_gc_collections_labels.copy()
+            )
+
     def _get_runtime_thread_count(
         self, options: CallbackOptions
     ) -> Iterable[Observation]:

instrumentation/opentelemetry-instrumentation-system-metrics/tests/test_system_metrics.py

@@ -136,6 +136,9 @@ def test_system_metrics_instrument(self):
             observer_names.append(
                 f"process.runtime.{self.implementation}.gc_count",
             )
+            observer_names.append(
+                f"process.runtime.{self.implementation}.gc_count",
+            )
         if sys.platform != "darwin":
             observer_names.append("system.network.connections")
 
@@ -939,6 +942,32 @@ def test_runtime_cpu_time(self, mock_process_cpu_times):
             f"process.runtime.{self.implementation}.cpu_time", expected
         )
 
+    @mock.patch("gc.get_count")
+    @skipIf(
+        python_implementation().lower() == "pypy", "not supported for pypy"
+    )
+    def test_runtime_get_count(self, mock_gc_get_count):
+        mock_gc_get_count.configure_mock(**{"return_value": (1, 2, 3)})
+
+        expected_gc_count = [
+            _SystemMetricsResult({"count": "0"}, 1),
+            _SystemMetricsResult({"count": "1"}, 2),
+            _SystemMetricsResult({"count": "2"}, 3),
+        ]
+        self._test_metrics(
+            f"process.runtime.{self.implementation}.gc_count",
+            expected_gc_count,
+        )
+        expected_gc_collections = [
+            _SystemMetricsResult({"generation": "0"}, 1),
+            _SystemMetricsResult({"generation": "1"}, 2),
+            _SystemMetricsResult({"generation": "2"}, 3),
+        ]
+        self._test_metrics(
+            f"process.runtime.{self.implementation}.gc_collections",
+            expected_gc_collections,
+        )
+
     @mock.patch("gc.get_count")
     @skipIf(
         python_implementation().lower() == "pypy", "not supported for pypy"