Issue #16481: multiprocessing no longer leaks process handles on Windows.

Lib/multiprocessing/forking.py

@@ -233,6 +233,7 @@ else:
                 self.returncode = None
                 self._handle = hp
                 self.sentinel = int(hp)
+                util.Finalize(self, _winapi.CloseHandle, (self.sentinel,))
 
                 # send information to child
                 Popen._tls.process_handle = int(hp)

Misc/NEWS

@@ -85,6 +85,8 @@ Core and Builtins
 Library
 -------
 
+- Issue #16481: multiprocessing no longer leaks process handles on Windows.
+
 - Issue #16140: The subprocess module no longer double closes its child
   subprocess.PIPE parent file descriptors on child error prior to exec().