pythongh-109888: Fix test_os _kill_with_event() on Windows (python#11…

…0421)

Replace os.kill() with proc.kill() which catchs PermissionError.

Rewrite _kill_with_event():

* Use subprocess context manager ("with proc:").
* Use sleeping_retry() to wait until the child process is ready.
* Replace SIGINT with proc.kill() on error.
* Replace 10 seconds with SHORT_TIMEOUT to wait until the process is
  ready.
* Replace 0.5 seconds with SHORT_TIMEOUT to wait for the process
  exit.

Lib/test/test_os.py

@@ -2566,30 +2566,34 @@ def _kill_with_event(self, event, name):
         tagname = "test_os_%s" % uuid.uuid1()
         m = mmap.mmap(-1, 1, tagname)
         m[0] = 0
+
         # Run a script which has console control handling enabled.
-        proc = subprocess.Popen([sys.executable,
-                   os.path.join(os.path.dirname(__file__),
-                                "win_console_handler.py"), tagname],
-                   creationflags=subprocess.CREATE_NEW_PROCESS_GROUP)
-        # Let the interpreter startup before we send signals. See #3137.
-        count, max = 0, 100
-        while count < max and proc.poll() is None:
-            if m[0] == 1:
-                break
-            time.sleep(0.1)
-            count += 1
-        else:
-            # Forcefully kill the process if we weren't able to signal it.
-            os.kill(proc.pid, signal.SIGINT)
-            self.fail("Subprocess didn't finish initialization")
-        os.kill(proc.pid, event)
-        # proc.send_signal(event) could also be done here.
-        # Allow time for the signal to be passed and the process to exit.
-        time.sleep(0.5)
-        if not proc.poll():
-            # Forcefully kill the process if we weren't able to signal it.
-            os.kill(proc.pid, signal.SIGINT)
-            self.fail("subprocess did not stop on {}".format(name))
+        script = os.path.join(os.path.dirname(__file__),
+                              "win_console_handler.py")
+        cmd = [sys.executable, script, tagname]
+        proc = subprocess.Popen(cmd,
+                                creationflags=subprocess.CREATE_NEW_PROCESS_GROUP)
+
+        with proc:
+            # Let the interpreter startup before we send signals. See #3137.
+            for _ in support.sleeping_retry(support.SHORT_TIMEOUT):
+                if proc.poll() is None:
+                    break
+            else:
+                # Forcefully kill the process if we weren't able to signal it.
+                proc.kill()
+                self.fail("Subprocess didn't finish initialization")
+
+            os.kill(proc.pid, event)
+
+            try:
+                # proc.send_signal(event) could also be done here.
+                # Allow time for the signal to be passed and the process to exit.
+                proc.wait(timeout=support.SHORT_TIMEOUT)
+            except subprocess.TimeoutExpired:
+                # Forcefully kill the process if we weren't able to signal it.
+                proc.kill()
+                self.fail("subprocess did not stop on {}".format(name))
 
     @unittest.skip("subprocesses aren't inheriting Ctrl+C property")
     @support.requires_subprocess()