gh-104090: Add exit code to multiprocessing ResourceTracker (GH-115410)

This builds on https://github.com/python/cpython/pull/106807, which adds
a return code to ResourceTracker, to make future debugging easier.
Testing this “in situ” proved difficult, since the global ResourceTracker is
involved in test infrastructure. So, the tests here create a new instance and
feed it fake data.

---------

Co-authored-by: Yonatan Bitton <yonatan.bitton@perception-point.io>
Co-authored-by: Yonatan Bitton <bityob@gmail.com>
Co-authored-by: Antoine Pitrou <antoine@python.org>

1 files changed, 34 insertions, 1 deletions

diff --git a/Lib/test/_test_multiprocessing.py b/Lib/test/_test_multiprocessing.py
index 94ce85c..e4183ee 100644
--- a/Lib/test/_test_multiprocessing.py
+++ b/Lib/test/_test_multiprocessing.py
@@ -5609,8 +5609,9 @@ class TestResourceTracker(unittest.TestCase):
         '''
         for rtype in resource_tracker._CLEANUP_FUNCS:
             with self.subTest(rtype=rtype):
-                if rtype == "noop":
+                if rtype in ("noop", "dummy"):
                     # Artefact resource type used by the resource_tracker
+                    # or tests
                     continue
                 r, w = os.pipe()
                 p = subprocess.Popen([sys.executable,
@@ -5730,6 +5731,38 @@ class TestResourceTracker(unittest.TestCase):
         with self.assertRaises(ValueError):
             resource_tracker.register(too_long_name_resource, rtype)
 
+    def _test_resource_tracker_leak_resources(self, cleanup):
+        # We use a separate instance for testing, since the main global
+        # _resource_tracker may be used to watch test infrastructure.
+        from multiprocessing.resource_tracker import ResourceTracker
+        tracker = ResourceTracker()
+        tracker.ensure_running()
+        self.assertTrue(tracker._check_alive())
+
+        self.assertIsNone(tracker._exitcode)
+        tracker.register('somename', 'dummy')
+        if cleanup:
+            tracker.unregister('somename', 'dummy')
+            expected_exit_code = 0
+        else:
+            expected_exit_code = 1
+
+        self.assertTrue(tracker._check_alive())
+        self.assertIsNone(tracker._exitcode)
+        tracker._stop()
+        self.assertEqual(tracker._exitcode, expected_exit_code)
+
+    def test_resource_tracker_exit_code(self):
+        """
+        Test the exit code of the resource tracker.
+
+        If no leaked resources were found, exit code should be 0, otherwise 1
+        """
+        for cleanup in [True, False]:
+            with self.subTest(cleanup=cleanup):
+                self._test_resource_tracker_leak_resources(
+                    cleanup=cleanup,
+                )
 
 class TestSimpleQueue(unittest.TestCase):