bpo-46720: Add support for path-like objects to multiprocessing.set_executable for Windows to be on a par with Unix-like systems

Doc/library/multiprocessing.rst

@@ -1075,6 +1075,9 @@ Miscellaneous
  .. versionchanged:: 3.4
  Now supported on Unix when the ``'spawn'`` start method is used.
 
+ .. versionchanged:: 3.11
+ Accepts a :term:`path-like object`.
+
 .. function:: set_start_method(method)
 
  Set the method which should be used to start child processes.

Lib/multiprocessing/spawn.py

@@ -33,18 +33,21 @@
  WINEXE = getattr(sys, 'frozen', False)
  WINSERVICE = sys.executable.lower().endswith("pythonservice.exe")
 
-if WINSERVICE:
- _python_exe = os.path.join(sys.exec_prefix, 'python.exe')
-else:
- _python_exe = sys.executable
-
 def set_executable(exe):
  global _python_exe
- _python_exe = exe
+ if sys.platform == 'win32':
+ _python_exe = os.fsdecode(exe)
+ else:
+ _python_exe = os.fsencode(exe)
 
 def get_executable():
  return _python_exe
 
+if WINSERVICE:
+ set_executable(os.path.join(sys.exec_prefix, 'python.exe'))
+else:
+ set_executable(sys.executable)
+
 #
 #
 #
@@ -86,7 +89,8 @@ def get_command_line(**kwds):
  prog = 'from multiprocessing.spawn import spawn_main; spawn_main(%s)'
  prog %= ', '.join('%s=%r' % item for item in kwds.items())
  opts = util._args_from_interpreter_flags()
- return [_python_exe] + opts + ['-c', prog, '--multiprocessing-fork']
+ exe = get_executable()
+ return [exe] + opts + ['-c', prog, '--multiprocessing-fork']
 
 
 def spawn_main(pipe_handle, parent_pid=None, tracker_fd=None):

Lib/multiprocessing/util.py

@@ -450,7 +450,7 @@ def spawnv_passfds(path, args, passfds):
  errpipe_read, errpipe_write = os.pipe()
  try:
  return _posixsubprocess.fork_exec(
- args, [os.fsencode(path)], True, passfds, None, None,
+ args, [path], True, passfds, None, None,
  -1, -1, -1, -1, -1, -1, errpipe_read, errpipe_write,
  False, False, None, None, None, -1, None)
  finally:

Lib/test/_test_multiprocessing.py

@@ -20,6 +20,7 @@
 import subprocess
 import struct
 import operator
+import pathlib
 import pickle
 import weakref
 import warnings
@@ -253,6 +254,21 @@ def test_current(self):
  self.assertEqual(current.ident, os.getpid())
  self.assertEqual(current.exitcode, None)
 
+ def test_set_executable(self):
+ if self.TYPE == 'threads':
+ self.skipTest(f'test not appropriate for {self.TYPE}')
+ paths = [
+ sys.executable, # str
+ sys.executable.encode(), # bytes
+ pathlib.Path(sys.executable) # os.PathLike
+ ]
+ for path in paths:
+ self.set_executable(path)
+ p = self.Process()
+ p.start()
+ p.join()
+ self.assertEqual(p.exitcode, 0)
+
  def test_args_argument(self):
  # bpo-45735: Using list or tuple as *args* in constructor could
  # achieve the same effect.
@@ -5779,6 +5795,7 @@ class ProcessesMixin(BaseMixin):
  current_process = staticmethod(multiprocessing.current_process)
  parent_process = staticmethod(multiprocessing.parent_process)
  active_children = staticmethod(multiprocessing.active_children)
+ set_executable = staticmethod(multiprocessing.set_executable)
  Pool = staticmethod(multiprocessing.Pool)
  Pipe = staticmethod(multiprocessing.Pipe)
  Queue = staticmethod(multiprocessing.Queue)

Misc/NEWS.d/next/Library/2022-02-11-23-11-35.bpo-46720.nY8spB.rst

@@ -0,0 +1,2 @@
+Add support for path-like objects to :func:`multiprocessing.set_executable` for
+Windows to be on a par with Unix-like systems. Patch by Géry Ogam.