bpo-38546: multiprocessing tests stop the resource tracker (GH-17641)

Multiprocessing and concurrent.futures tests now stop the resource
tracker process when tests complete.

Add ResourceTracker._stop() method to
multiprocessing.resource_tracker.

Add _cleanup_tests() helper function to multiprocessing.util: share
code between multiprocessing and concurrent.futures tests.

2 files changed, 38 insertions, 0 deletions

diff --git a/Lib/multiprocessing/resource_tracker.py b/Lib/multiprocessing/resource_tracker.py
index 61a6dd6..c9bfa9b 100644
--- a/Lib/multiprocessing/resource_tracker.py
+++ b/Lib/multiprocessing/resource_tracker.py
@@ -50,6 +50,19 @@ class ResourceTracker(object):
         self._fd = None
         self._pid = None
 
+    def _stop(self):
+        with self._lock:
+            if self._fd is None:
+                # not running
+                return
+
+            # closing the "alive" file descriptor stops main()
+            os.close(self._fd)
+            self._fd = None
+
+            os.waitpid(self._pid, 0)
+            self._pid = None
+
     def getfd(self):
         self.ensure_running()
         return self._fd
diff --git a/Lib/multiprocessing/util.py b/Lib/multiprocessing/util.py
index 3e640b9..4bc7782 100644
--- a/Lib/multiprocessing/util.py
+++ b/Lib/multiprocessing/util.py
@@ -439,3 +439,28 @@ def close_fds(*fds):
     """Close each file descriptor given as an argument"""
     for fd in fds:
         os.close(fd)
+
+
+def _cleanup_tests():
+    """Cleanup multiprocessing resources when multiprocessing tests
+    completed."""
+
+    from test import support
+
+    # cleanup multiprocessing
+    process._cleanup()
+
+    # Stop the ForkServer process if it's running
+    from multiprocessing import forkserver
+    forkserver._forkserver._stop()
+
+    # Stop the ResourceTracker process if it's running
+    from multiprocessing import resource_tracker
+    resource_tracker._resource_tracker._stop()
+
+    # bpo-37421: Explicitly call _run_finalizers() to remove immediately
+    # temporary directories created by multiprocessing.util.get_temp_dir().
+    _run_finalizers()
+    support.gc_collect()
+
+    support.reap_children()