fix(ray): stop instrumenting ray internal actors (#15083)

Before this change, we were instrumenting internal/private ray actors
which was leading to noise/orphan spans.

We now don't instrument internal actors and actors whose names start by
`_`

Author: dubloom

ddtrace/contrib/internal/ray/__init__.py

@@ -66,4 +66,5 @@
 
 - The integration disables Ray's built-in OpenTelemetry tracing to avoid duplicate telemetry.
 - Actor methods like ``ping`` and ``_polling`` are excluded from tracing to reduce noise.
+- Actors whose names start with an underscore (_) are not instrumented.
 """

ddtrace/contrib/internal/ray/patch.py

@@ -71,6 +71,7 @@
 RAY_MODULE_DENYLIST = {
     "ray.dag",
     "ray.experimental",
+    "ray.data._internal",
 }
 
 
@@ -499,6 +500,10 @@ def inject_tracing_into_actor_class(wrapped, instance, args, kwargs):
     if any(module_name.startswith(denied_module) for denied_module in RAY_MODULE_DENYLIST):
         return cls
 
+    # Actor beginning with _ are considered internal and will not be traced
+    if class_name.startswith("_"):
+        return cls
+
     # Determine if the class is a JobSupervisor
     is_job_supervisor = f"{module_name}.{class_name}" == "ray.dashboard.modules.job.job_supervisor.JobSupervisor"
     # We do not want to instrument ping and polling to remove noise

releasenotes/notes/ray-fix-internal-actors-57d41ebbcb000b98.yaml

@@ -0,0 +1,5 @@
+---
+fixes:
+  - |
+    ray: This fix stops instrumenting internal Ray actors (those starting with underscore) that were
+    causing excessive noise, and adds ``ray.data._internal`` to the module denylist.

tests/contrib/ray/test_ray.py

@@ -104,6 +104,28 @@ def increment_get_and_double(self):
 
         assert current_value == 2, f"Unexpected result: {current_value}"
 
+    @pytest.mark.snapshot(token="tests.contrib.ray.test_ray.test_ignored_actored", ignores=RAY_SNAPSHOT_IGNORES)
+    def test_ignored_actors(self):
+        @ray.remote
+        class _InternalActor:
+            def one(self):
+                return 1
+
+        actor = _InternalActor.remote()
+        current_value = ray.get(actor.one.remote())
+        assert current_value == 1, f"Unexpected result: {current_value}"
+
+        class MockDeniedActor:
+            def get_value(self):
+                return 42
+
+        MockDeniedActor.__module__ = "ray.data._internal"
+        MockDeniedActor = ray.remote(MockDeniedActor)
+
+        denied_actor = MockDeniedActor.remote()
+        value = ray.get(denied_actor.get_value.remote())
+        assert value == 42, f"Unexpected result: {value}"
+
     @pytest.mark.snapshot(token="tests.contrib.ray.test_ray.test_nested_tasks", ignores=RAY_SNAPSHOT_IGNORES)
     def test_nested_tasks(self):
         @ray.remote