`opentelemetry-instrumentation-system-metrics`: Add `cpython.gc.collected_objects` and `cpython.gc.uncollectable_objects` metrics (#3666)

* `opentelemetry-instrumentation-system-metrics`: Add `cpython.gc.collected_objects` and `cpython.gc.uncollectable_objects` metrics

* Update __init__.py

* Update CHANGELOG.md

---------

Co-authored-by: Riccardo Magliocchetti <riccardo.magliocchetti@gmail.com>
Co-authored-by: Emídio Neto <9735060+emdneto@users.noreply.github.com>

CHANGELOG.md

@@ -24,6 +24,9 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 
 - `opentelemetry-instrumentation-confluent-kafka` Add support for confluent-kafka <=2.11.0
   ([#3685](https://github.com/open-telemetry/opentelemetry-python-contrib/pull/3685))
+- `opentelemetry-instrumentation-system-metrics`: Add `cpython.gc.collected_objects` and `cpython.gc.uncollectable_objects` metrics
+  ([#3666](https://github.com/open-telemetry/opentelemetry-python-contrib/pull/3666))
+
 
 ## Version 1.36.0/0.57b0 (2025-07-29)
 

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

@@ -11,6 +11,8 @@
 # WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 # See the License for the specific language governing permissions and
 # limitations under the License.
+# pylint: disable=too-many-lines
+
 """
 Instrument to report system (CPU, memory, network) and
 process (CPU, memory, garbage collection) metrics. By default, the
@@ -45,6 +47,8 @@ following metrics are configured:
         "process.runtime.cpu.time": ["user", "system"],
         "process.runtime.gc_count": None,
         "cpython.gc.collections": None,
+        "cpython.gc.collected_objects": None,
+        "cpython.gc.uncollectable_objects": None,
         "process.runtime.thread_count": None,
         "process.runtime.cpu.utilization": None,
         "process.runtime.context_switches": ["involuntary", "voluntary"],
@@ -138,6 +142,8 @@ _DEFAULT_CONFIG: dict[str, list[str] | None] = {
     "process.runtime.cpu.time": ["user", "system"],
     "process.runtime.gc_count": None,
     "cpython.gc.collections": None,
+    "cpython.gc.collected_objects": None,
+    "cpython.gc.uncollectable_objects": None,
     "process.runtime.thread_count": None,
     "process.runtime.cpu.utilization": None,
     "process.runtime.context_switches": ["involuntary", "voluntary"],
@@ -199,6 +205,8 @@ class SystemMetricsInstrumentor(BaseInstrumentor):
         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_gc_collected_objects_labels = self._labels.copy()
+        self._runtime_gc_uncollectable_objects_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()
@@ -486,6 +494,32 @@ class SystemMetricsInstrumentor(BaseInstrumentor):
                     unit="{collection}",
                 )
 
+        if "cpython.gc.collected_objects" in self._config:
+            if self._python_implementation == "pypy":
+                _logger.warning(
+                    "The cpython.gc.collected_objects metric won't be collected because the interpreter is PyPy"
+                )
+            else:
+                self._meter.create_observable_counter(
+                    name="cpython.gc.collected_objects",
+                    callbacks=[self._get_runtime_gc_collected_objects],
+                    description="The total number of objects collected since interpreter start.",
+                    unit="{object}",
+                )
+
+        if "cpython.gc.uncollectable_objects" in self._config:
+            if self._python_implementation == "pypy":
+                _logger.warning(
+                    "The cpython.gc.uncollectable_objects metric won't be collected because the interpreter is PyPy"
+                )
+            else:
+                self._meter.create_observable_counter(
+                    name="cpython.gc.uncollectable_objects",
+                    callbacks=[self._get_runtime_gc_uncollectable_objects],
+                    description="The total number of uncollectable objects found since interpreter start.",
+                    unit="{object}",
+                )
+
         if "process.runtime.thread_count" in self._config:
             self._meter.create_observable_up_down_counter(
                 name=f"process.runtime.{self._python_implementation}.thread_count",
@@ -911,6 +945,32 @@ class SystemMetricsInstrumentor(BaseInstrumentor):
                 stat["collections"], self._runtime_gc_collections_labels.copy()
             )
 
+    def _get_runtime_gc_collected_objects(
+        self, options: CallbackOptions
+    ) -> Iterable[Observation]:
+        """Observer callback for garbage collection collected objects"""
+        for index, stat in enumerate(gc.get_stats()):
+            self._runtime_gc_collected_objects_labels["generation"] = str(
+                index
+            )
+            yield Observation(
+                stat["collected"],
+                self._runtime_gc_collected_objects_labels.copy(),
+            )
+
+    def _get_runtime_gc_uncollectable_objects(
+        self, options: CallbackOptions
+    ) -> Iterable[Observation]:
+        """Observer callback for garbage collection uncollectable objects"""
+        for index, stat in enumerate(gc.get_stats()):
+            self._runtime_gc_uncollectable_objects_labels["generation"] = str(
+                index
+            )
+            yield Observation(
+                stat["uncollectable"],
+                self._runtime_gc_uncollectable_objects_labels.copy(),
+            )
+
     def _get_runtime_thread_count(
         self, options: CallbackOptions
     ) -> Iterable[Observation]:

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

@@ -139,6 +139,12 @@ class TestSystemMetrics(TestBase):
             observer_names.append(
                 "cpython.gc.collections",
             )
+            observer_names.append(
+                "cpython.gc.collected_objects",
+            )
+            observer_names.append(
+                "cpython.gc.uncollectable_objects",
+            )
         if sys.platform != "darwin":
             observer_names.append("system.network.connections")
 
@@ -983,6 +989,54 @@ class TestSystemMetrics(TestBase):
             expected_gc_collections,
         )
 
+    @mock.patch("gc.get_stats")
+    @skipIf(
+        python_implementation().lower() == "pypy", "not supported for pypy"
+    )
+    def test_runtime_get_gc_collected_objects(self, mock_gc_get_stats):
+        mock_gc_get_stats.configure_mock(
+            **{
+                "return_value": [
+                    {"collections": 10, "collected": 100, "uncollectable": 1},
+                    {"collections": 20, "collected": 200, "uncollectable": 2},
+                    {"collections": 30, "collected": 300, "uncollectable": 3},
+                ]
+            }
+        )
+        expected_gc_collected_objects = [
+            _SystemMetricsResult({"generation": "0"}, 100),
+            _SystemMetricsResult({"generation": "1"}, 200),
+            _SystemMetricsResult({"generation": "2"}, 300),
+        ]
+        self._test_metrics(
+            "cpython.gc.collected_objects",
+            expected_gc_collected_objects,
+        )
+
+    @mock.patch("gc.get_stats")
+    @skipIf(
+        python_implementation().lower() == "pypy", "not supported for pypy"
+    )
+    def test_runtime_get_gc_uncollectable_objects(self, mock_gc_get_stats):
+        mock_gc_get_stats.configure_mock(
+            **{
+                "return_value": [
+                    {"collections": 10, "collected": 100, "uncollectable": 1},
+                    {"collections": 20, "collected": 200, "uncollectable": 2},
+                    {"collections": 30, "collected": 300, "uncollectable": 3},
+                ]
+            }
+        )
+        expected_gc_uncollectable_objects = [
+            _SystemMetricsResult({"generation": "0"}, 1),
+            _SystemMetricsResult({"generation": "1"}, 2),
+            _SystemMetricsResult({"generation": "2"}, 3),
+        ]
+        self._test_metrics(
+            "cpython.gc.uncollectable_objects",
+            expected_gc_uncollectable_objects,
+        )
+
     @mock.patch("psutil.Process.num_ctx_switches")
     def test_runtime_context_switches(self, mock_process_num_ctx_switches):
         PCtxSwitches = namedtuple("PCtxSwitches", ["voluntary", "involuntary"])