ENH test check pid of semaphore_tracker

Author: tomMoral

Lib/multiprocessing/spawn.py

@@ -169,6 +169,11 @@ def get_preparation_data(name):
     else:
         sys_path[i] = process.ORIGINAL_DIR
 
+    if sys.platform != "win32":
+        from .semaphore_tracker import _semaphore_tracker
+        _semaphore_tracker.ensure_running()
+        d['semaphore_tracker_pid'] = _semaphore_tracker._pid
+
     d.update(
         name=name,
         sys_path=sys_path,
@@ -231,6 +236,10 @@ def prepare(data):
     if 'start_method' in data:
         set_start_method(data['start_method'], force=True)
 
+    if 'semaphore_tracker_pid' in data:
+        from .semaphore_tracker import _semaphore_tracker
+        _semaphore_tracker._pid = data['semaphore_tracker_pid']
+
     if 'init_main_from_name' in data:
         _fixup_main_from_name(data['init_main_from_name'])
     elif 'init_main_from_path' in data:

Lib/test/_test_multiprocessing.py

@@ -4896,10 +4896,10 @@ def test_semaphore_tracker_sigkill(self):
         self.check_semaphore_tracker_death(signal.SIGKILL, True)
 
     @staticmethod
-    def _is_semaphore_tracker_reused(conn):
+    def _is_semaphore_tracker_reused(conn, pid):
         from multiprocessing.semaphore_tracker import _semaphore_tracker
         _semaphore_tracker.ensure_running()
-        reused = _semaphore_tracker._pid is None
+        reused = _semaphore_tracker._pid  == pid
         reused &= _semaphore_tracker._check_alive()
         conn.send(reused)
 
@@ -4911,7 +4911,7 @@ def test_semaphore_tracker_reused(self):
         ctx = multiprocessing.get_context("spawn")
         r, w = ctx.Pipe(duplex=False)
         p = ctx.Process(target=self._is_semaphore_tracker_reused,
-                        args=(w,))
+                        args=(w, pid))
         p.start()
         is_semaphore_tracker_reused = r.recv()