collect threads count in opentelemetry-instrumentation-system-metrics (#1339)

* collect threads count in opentelemetry-instrumentation-system-metrics

* update

* avoid devidedByZero exception when sawp memory is 0

* add ut

* change log

* lint

* lint

Co-authored-by: Srikanth Chekuri <srikanth.chekuri92@gmail.com>

Author: yulin-li

CHANGELOG.md

@@ -7,6 +7,10 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 
 ## [Unreleased](https://github.com/open-telemetry/opentelemetry-python/compare/v1.13.0-0.34b0...HEAD)
 
+### Added
+
+- `opentelemetry-instrumentation-system-metrics` add supports to collect system thread count. ([#1339](https://github.com/open-telemetry/opentelemetry-python-contrib/pull/1339))
+
 ## [1.13.0-0.34b0](https://github.com/open-telemetry/opentelemetry-python/releases/tag/v1.13.0-0.34b0) - 2022-09-26
 
 
@@ -26,14 +30,14 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
   ([#1253](https://github.com/open-telemetry/opentelemetry-python-contrib/pull/1253))
 - Add metric instrumentation in starlette
   ([#1327](https://github.com/open-telemetry/opentelemetry-python-contrib/pull/1327))
-  
+
 
 ### Fixed
 
 - `opentelemetry-instrumentation-boto3sqs` Make propagation compatible with other SQS instrumentations, add 'messaging.url' span attribute, and fix missing package dependencies.
-  ([#1234](https://github.com/open-telemetry/opentelemetry-python-contrib/pull/1234)) 
+  ([#1234](https://github.com/open-telemetry/opentelemetry-python-contrib/pull/1234))
 - `opentelemetry-instrumentation-pymongo` Change span names to not contain queries but only database name and command name
-  ([#1247](https://github.com/open-telemetry/opentelemetry-python-contrib/pull/1247)) 
+  ([#1247](https://github.com/open-telemetry/opentelemetry-python-contrib/pull/1247))
 - restoring metrics in django framework
   ([#1208](https://github.com/open-telemetry/opentelemetry-python-contrib/pull/1208))
 - `opentelemetry-instrumentation-aiohttp-client` Fix producing additional spans with each newly created ClientSession

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

@@ -33,6 +33,7 @@
         "system.network.errors": ["transmit", "receive"],
         "system.network.io": ["transmit", "receive"],
         "system.network.connections": ["family", "type"],
+        "system.thread_count": None
         "runtime.memory": ["rss", "vms"],
         "runtime.cpu.time": ["user", "system"],
     }
@@ -71,6 +72,7 @@
 
 import gc
 import os
+import threading
 from platform import python_implementation
 from typing import Collection, Dict, Iterable, List, Optional
 
@@ -99,6 +101,7 @@
     "system.network.errors": ["transmit", "receive"],
     "system.network.io": ["transmit", "receive"],
     "system.network.connections": ["family", "type"],
+    "system.thread_count": None,
     "runtime.memory": ["rss", "vms"],
     "runtime.cpu.time": ["user", "system"],
     "runtime.gc_count": None,
@@ -142,6 +145,8 @@ def __init__(
         self._system_network_io_labels = self._labels.copy()
         self._system_network_connections_labels = self._labels.copy()
 
+        self._system_thread_count_labels = self._labels.copy()
+
         self._runtime_memory_labels = self._labels.copy()
         self._runtime_cpu_time_labels = self._labels.copy()
         self._runtime_gc_count_labels = self._labels.copy()
@@ -311,6 +316,13 @@ def _instrument(self, **kwargs):
                 unit="connections",
             )
 
+        if "system.thread_count" in self._config:
+            self._meter.create_observable_gauge(
+                name="system.thread_count",
+                callbacks=[self._get_system_thread_count],
+                description="System active threads count",
+            )
+
         if "runtime.memory" in self._config:
             self._meter.create_observable_counter(
                 name=f"runtime.{self._python_implementation}.memory",
@@ -593,6 +605,14 @@ def _get_system_network_connections(
                 connection_counter["labels"],
             )
 
+    def _get_system_thread_count(
+        self, options: CallbackOptions
+    ) -> Iterable[Observation]:
+        """Observer callback for active thread count"""
+        yield Observation(
+            threading.active_count(), self._system_thread_count_labels
+        )
+
     def _get_runtime_memory(
         self, options: CallbackOptions
     ) -> Iterable[Observation]:

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

@@ -51,6 +51,7 @@ def __init__(self, attributes, value) -> None:
         self.value = value
 
 
+# pylint:disable=too-many-public-methods
 class TestSystemMetrics(TestBase):
     def setUp(self):
         super().setUp()
@@ -75,7 +76,7 @@ def test_system_metrics_instrument(self):
             for scope_metrics in resource_metrics.scope_metrics:
                 for metric in scope_metrics.metrics:
                     metric_names.append(metric.name)
-        self.assertEqual(len(metric_names), 17)
+        self.assertEqual(len(metric_names), 18)
 
         observer_names = [
             "system.cpu.time",
@@ -92,6 +93,7 @@ def test_system_metrics_instrument(self):
             "system.network.errors",
             "system.network.io",
             "system.network.connections",
+            "system.thread_count",
             f"runtime.{self.implementation}.memory",
             f"runtime.{self.implementation}.cpu_time",
             f"runtime.{self.implementation}.gc_count",
@@ -680,6 +682,13 @@ def test_system_network_connections(self, mock_net_connections):
         ]
         self._test_metrics("system.network.connections", expected)
 
+    @mock.patch("threading.active_count")
+    def test_system_thread_count(self, threading_active_count):
+        threading_active_count.return_value = 42
+
+        expected = [_SystemMetricsResult({}, 42)]
+        self._test_metrics("system.thread_count", expected)
+
     @mock.patch("psutil.Process.memory_info")
     def test_runtime_memory(self, mock_process_memory_info):