Error occured when trying to use `ProcessLocal` with `concurrent.futures`

[Chris-fullerton]

Python 3.10.11 (main, Apr 20 2023, 13:58:42) [Clang 14.0.6 ] on darwin

Error occured when trying to use ProcessLocal with concurrent.futures:

Traceback (most recent call last):
  File "<string>", line 1, in <module>
  File "/Users/christopherchang/miniconda3/envs/facepcs/lib/python3.10/multiprocessing/spawn.py", line 116, in spawn_main
Traceback (most recent call last):
  File "<string>", line 1, in <module>
  File "/Users/christopherchang/miniconda3/envs/facepcs/lib/python3.10/multiprocessing/spawn.py", line 116, in spawn_main
    exitcode = _main(fd, parent_sentinel)
  File "/Users/christopherchang/miniconda3/envs/facepcs/lib/python3.10/multiprocessing/spawn.py", line 125, in _main
    exitcode = _main(fd, parent_sentinel)
  File "/Users/christopherchang/miniconda3/envs/facepcs/lib/python3.10/multiprocessing/spawn.py", line 125, in _main
Traceback (most recent call last):
  File "<string>", line 1, in <module>
  File "/Users/christopherchang/miniconda3/envs/facepcs/lib/python3.10/multiprocessing/spawn.py", line 116, in spawn_main
    prepare(preparation_data)
  File "/Users/christopherchang/miniconda3/envs/facepcs/lib/python3.10/multiprocessing/spawn.py", line 236, in prepare
    prepare(preparation_data)
  File "/Users/christopherchang/miniconda3/envs/facepcs/lib/python3.10/multiprocessing/spawn.py", line 236, in prepare
Traceback (most recent call last):
  File "<string>", line 1, in <module>
  File "/Users/christopherchang/miniconda3/envs/facepcs/lib/python3.10/multiprocessing/spawn.py", line 116, in spawn_main
    exitcode = _main(fd, parent_sentinel)
  File "/Users/christopherchang/miniconda3/envs/facepcs/lib/python3.10/multiprocessing/spawn.py", line 125, in _main
    _fixup_main_from_path(data['init_main_from_path'])
  File "/Users/christopherchang/miniconda3/envs/facepcs/lib/python3.10/multiprocessing/spawn.py", line 287, in _fixup_main_from_path
    _fixup_main_from_path(data['init_main_from_path'])
  File "/Users/christopherchang/miniconda3/envs/facepcs/lib/python3.10/multiprocessing/spawn.py", line 287, in _fixup_main_from_path
    prepare(preparation_data)
  File "/Users/christopherchang/miniconda3/envs/facepcs/lib/python3.10/multiprocessing/spawn.py", line 236, in prepare
    main_content = runpy.run_path(main_path,
  File "/Users/christopherchang/miniconda3/envs/facepcs/lib/python3.10/runpy.py", line 289, in run_path
    exitcode = _main(fd, parent_sentinel)
  File "/Users/christopherchang/miniconda3/envs/facepcs/lib/python3.10/multiprocessing/spawn.py", line 125, in _main
    main_content = runpy.run_path(main_path,
  File "/Users/christopherchang/miniconda3/envs/facepcs/lib/python3.10/runpy.py", line 289, in run_path
    _fixup_main_from_path(data['init_main_from_path'])
  File "/Users/christopherchang/miniconda3/envs/facepcs/lib/python3.10/multiprocessing/spawn.py", line 287, in _fixup_main_from_path
    return _run_module_code(code, init_globals, run_name,
  File "/Users/christopherchang/miniconda3/envs/facepcs/lib/python3.10/runpy.py", line 96, in _run_module_code
Traceback (most recent call last):
  File "<string>", line 1, in <module>
    prepare(preparation_data)
  File "/Users/christopherchang/miniconda3/envs/facepcs/lib/python3.10/multiprocessing/spawn.py", line 236, in prepare
  File "/Users/christopherchang/miniconda3/envs/facepcs/lib/python3.10/multiprocessing/spawn.py", line 116, in spawn_main
    _run_code(code, mod_globals, init_globals,
  File "/Users/christopherchang/miniconda3/envs/facepcs/lib/python3.10/runpy.py", line 86, in _run_code
    _fixup_main_from_path(data['init_main_from_path'])
  File "/Users/christopherchang/miniconda3/envs/facepcs/lib/python3.10/multiprocessing/spawn.py", line 287, in _fixup_main_from_path
    return _run_module_code(code, init_globals, run_name,
  File "/Users/christopherchang/miniconda3/envs/facepcs/lib/python3.10/runpy.py", line 96, in _run_module_code
    main_content = runpy.run_path(main_path,
  File "/Users/christopherchang/miniconda3/envs/facepcs/lib/python3.10/runpy.py", line 289, in run_path
    exitcode = _main(fd, parent_sentinel)
  File "/Users/christopherchang/miniconda3/envs/facepcs/lib/python3.10/multiprocessing/spawn.py", line 125, in _main
    main_content = runpy.run_path(main_path,
  File "/Users/christopherchang/miniconda3/envs/facepcs/lib/python3.10/runpy.py", line 289, in run_path
    _run_code(code, mod_globals, init_globals,
  File "/Users/christopherchang/miniconda3/envs/facepcs/lib/python3.10/runpy.py", line 86, in _run_code
    prepare(preparation_data)
  File "/Users/christopherchang/miniconda3/envs/facepcs/lib/python3.10/multiprocessing/spawn.py", line 236, in prepare
    exec(code, run_globals)
  File "/Users/christopherchang/TEST/python_test/test.py", line 8, in <module>
    return _run_module_code(code, init_globals, run_name,
  File "/Users/christopherchang/miniconda3/envs/facepcs/lib/python3.10/runpy.py", line 96, in _run_module_code
    multi_process()
  File "/Users/christopherchang/TEST/python_test/test.py", line 7, in multi_process
    exec(code, run_globals)
  File "/Users/christopherchang/TEST/python_test/test.py", line 8, in <module>
    _fixup_main_from_path(data['init_main_from_path'])
  File "/Users/christopherchang/miniconda3/envs/facepcs/lib/python3.10/multiprocessing/spawn.py", line 287, in _fixup_main_from_path
    return _run_module_code(code, init_globals, run_name,
  File "/Users/christopherchang/miniconda3/envs/facepcs/lib/python3.10/runpy.py", line 96, in _run_module_code
    _run_code(code, mod_globals, init_globals,
  File "/Users/christopherchang/miniconda3/envs/facepcs/lib/python3.10/runpy.py", line 86, in _run_code
    executor.submit(tapo.SessionProcess, i) 
  File "/Users/christopherchang/miniconda3/envs/facepcs/lib/python3.10/concurrent/futures/process.py", line 737, in submit
    main_content = runpy.run_path(main_path,
  File "/Users/christopherchang/miniconda3/envs/facepcs/lib/python3.10/runpy.py", line 289, in run_path
    _run_code(code, mod_globals, init_globals,
  File "/Users/christopherchang/miniconda3/envs/facepcs/lib/python3.10/runpy.py", line 86, in _run_code
    multi_process()
  File "/Users/christopherchang/TEST/python_test/test.py", line 7, in multi_process
    exec(code, run_globals)
  File "/Users/christopherchang/TEST/python_test/test.py", line 8, in <module>
    self._adjust_process_count()
  File "/Users/christopherchang/miniconda3/envs/facepcs/lib/python3.10/concurrent/futures/process.py", line 697, in _adjust_process_count
    multi_process()
  File "/Users/christopherchang/TEST/python_test/test.py", line 7, in multi_process
    return _run_module_code(code, init_globals, run_name,
  File "/Users/christopherchang/miniconda3/envs/facepcs/lib/python3.10/runpy.py", line 96, in _run_module_code
    executor.submit(tapo.SessionProcess, i) 
  File "/Users/christopherchang/miniconda3/envs/facepcs/lib/python3.10/concurrent/futures/process.py", line 737, in submit
    exec(code, run_globals)
  File "/Users/christopherchang/TEST/python_test/test.py", line 8, in <module>
    self._spawn_process()
  File "/Users/christopherchang/miniconda3/envs/facepcs/lib/python3.10/concurrent/futures/process.py", line 714, in _spawn_process
    executor.submit(tapo.SessionProcess, i) 
  File "/Users/christopherchang/miniconda3/envs/facepcs/lib/python3.10/concurrent/futures/process.py", line 737, in submit
    _run_code(code, mod_globals, init_globals,
  File "/Users/christopherchang/miniconda3/envs/facepcs/lib/python3.10/runpy.py", line 86, in _run_code
    self._adjust_process_count()
  File "/Users/christopherchang/miniconda3/envs/facepcs/lib/python3.10/concurrent/futures/process.py", line 697, in _adjust_process_count
    multi_process()
  File "/Users/christopherchang/TEST/python_test/test.py", line 7, in multi_process
    p.start()
  File "/Users/christopherchang/miniconda3/envs/facepcs/lib/python3.10/multiprocessing/process.py", line 121, in start
    exec(code, run_globals)
  File "/Users/christopherchang/TEST/python_test/test.py", line 8, in <module>
    self._popen = self._Popen(self)
    self._adjust_process_count()
  File "/Users/christopherchang/miniconda3/envs/facepcs/lib/python3.10/multiprocessing/context.py", line 288, in _Popen
  File "/Users/christopherchang/miniconda3/envs/facepcs/lib/python3.10/concurrent/futures/process.py", line 697, in _adjust_process_count
    executor.submit(tapo.SessionProcess, i) 
  File "/Users/christopherchang/miniconda3/envs/facepcs/lib/python3.10/concurrent/futures/process.py", line 737, in submit
    self._spawn_process()
  File "/Users/christopherchang/miniconda3/envs/facepcs/lib/python3.10/concurrent/futures/process.py", line 714, in _spawn_process
    return Popen(process_obj)
    multi_process()
  File "/Users/christopherchang/miniconda3/envs/facepcs/lib/python3.10/multiprocessing/popen_spawn_posix.py", line 32, in __init__
  File "/Users/christopherchang/TEST/python_test/test.py", line 7, in multi_process
    self._adjust_process_count()
  File "/Users/christopherchang/miniconda3/envs/facepcs/lib/python3.10/concurrent/futures/process.py", line 697, in _adjust_process_count
    p.start()
  File "/Users/christopherchang/miniconda3/envs/facepcs/lib/python3.10/multiprocessing/process.py", line 121, in start
    self._spawn_process()
  File "/Users/christopherchang/miniconda3/envs/facepcs/lib/python3.10/concurrent/futures/process.py", line 714, in _spawn_process
    super().__init__(process_obj)
  File "/Users/christopherchang/miniconda3/envs/facepcs/lib/python3.10/multiprocessing/popen_fork.py", line 19, in __init__
    self._spawn_process()
  File "/Users/christopherchang/miniconda3/envs/facepcs/lib/python3.10/concurrent/futures/process.py", line 714, in _spawn_process
    executor.submit(tapo.SessionProcess, i) 
  File "/Users/christopherchang/miniconda3/envs/facepcs/lib/python3.10/concurrent/futures/process.py", line 737, in submit
    self._popen = self._Popen(self)
  File "/Users/christopherchang/miniconda3/envs/facepcs/lib/python3.10/multiprocessing/context.py", line 288, in _Popen
    p.start()
  File "/Users/christopherchang/miniconda3/envs/facepcs/lib/python3.10/multiprocessing/process.py", line 121, in start
    self._launch(process_obj)
  File "/Users/christopherchang/miniconda3/envs/facepcs/lib/python3.10/multiprocessing/popen_spawn_posix.py", line 42, in _launch
    self._popen = self._Popen(self)
  File "/Users/christopherchang/miniconda3/envs/facepcs/lib/python3.10/multiprocessing/context.py", line 288, in _Popen
    return Popen(process_obj)
  File "/Users/christopherchang/miniconda3/envs/facepcs/lib/python3.10/multiprocessing/popen_spawn_posix.py", line 32, in __init__
    self._adjust_process_count()
  File "/Users/christopherchang/miniconda3/envs/facepcs/lib/python3.10/concurrent/futures/process.py", line 697, in _adjust_process_count
Traceback (most recent call last):
  File "<string>", line 1, in <module>
    p.start()
  File "/Users/christopherchang/miniconda3/envs/facepcs/lib/python3.10/multiprocessing/process.py", line 121, in start
  File "/Users/christopherchang/miniconda3/envs/facepcs/lib/python3.10/multiprocessing/spawn.py", line 116, in spawn_main
Traceback (most recent call last):
  File "<string>", line 1, in <module>
  File "/Users/christopherchang/miniconda3/envs/facepcs/lib/python3.10/multiprocessing/spawn.py", line 116, in spawn_main
    prep_data = spawn.get_preparation_data(process_obj._name)
  File "/Users/christopherchang/miniconda3/envs/facepcs/lib/python3.10/multiprocessing/spawn.py", line 154, in get_preparation_data
    return Popen(process_obj)
  File "/Users/christopherchang/miniconda3/envs/facepcs/lib/python3.10/multiprocessing/popen_spawn_posix.py", line 32, in __init__
    self._popen = self._Popen(self)
  File "/Users/christopherchang/miniconda3/envs/facepcs/lib/python3.10/multiprocessing/context.py", line 288, in _Popen
    super().__init__(process_obj)
  File "/Users/christopherchang/miniconda3/envs/facepcs/lib/python3.10/multiprocessing/popen_fork.py", line 19, in __init__
    exitcode = _main(fd, parent_sentinel)
  File "/Users/christopherchang/miniconda3/envs/facepcs/lib/python3.10/multiprocessing/spawn.py", line 125, in _main
    self._spawn_process()
  File "/Users/christopherchang/miniconda3/envs/facepcs/lib/python3.10/concurrent/futures/process.py", line 714, in _spawn_process
    exitcode = _main(fd, parent_sentinel)
  File "/Users/christopherchang/miniconda3/envs/facepcs/lib/python3.10/multiprocessing/spawn.py", line 125, in _main
    _check_not_importing_main()
    return Popen(process_obj)
  File "/Users/christopherchang/miniconda3/envs/facepcs/lib/python3.10/multiprocessing/popen_spawn_posix.py", line 32, in __init__
    prepare(preparation_data)
  File "/Users/christopherchang/miniconda3/envs/facepcs/lib/python3.10/multiprocessing/spawn.py", line 134, in _check_not_importing_main
  File "/Users/christopherchang/miniconda3/envs/facepcs/lib/python3.10/multiprocessing/spawn.py", line 236, in prepare
    super().__init__(process_obj)
  File "/Users/christopherchang/miniconda3/envs/facepcs/lib/python3.10/multiprocessing/popen_fork.py", line 19, in __init__
    prepare(preparation_data)
    self._launch(process_obj)
  File "/Users/christopherchang/miniconda3/envs/facepcs/lib/python3.10/multiprocessing/spawn.py", line 236, in prepare
  File "/Users/christopherchang/miniconda3/envs/facepcs/lib/python3.10/multiprocessing/popen_spawn_posix.py", line 42, in _launch
    p.start()
  File "/Users/christopherchang/miniconda3/envs/facepcs/lib/python3.10/multiprocessing/process.py", line 121, in start
    super().__init__(process_obj)
  File "/Users/christopherchang/miniconda3/envs/facepcs/lib/python3.10/multiprocessing/popen_fork.py", line 19, in __init__
    _fixup_main_from_path(data['init_main_from_path'])
  File "/Users/christopherchang/miniconda3/envs/facepcs/lib/python3.10/multiprocessing/spawn.py", line 287, in _fixup_main_from_path
    self._launch(process_obj)
  File "/Users/christopherchang/miniconda3/envs/facepcs/lib/python3.10/multiprocessing/popen_spawn_posix.py", line 42, in _launch
    prep_data = spawn.get_preparation_data(process_obj._name)
  File "/Users/christopherchang/miniconda3/envs/facepcs/lib/python3.10/multiprocessing/spawn.py", line 154, in get_preparation_data
    self._popen = self._Popen(self)
  File "/Users/christopherchang/miniconda3/envs/facepcs/lib/python3.10/multiprocessing/context.py", line 288, in _Popen
    raise RuntimeError('''
RuntimeError: 
        An attempt has been made to start a new process before the
        current process has finished its bootstrapping phase.

        This probably means that you are not using fork to start your
        child processes and you have forgotten to use the proper idiom
        in the main module:

            if __name__ == '__main__':
                freeze_support()
                ...

        The "freeze_support()" line can be omitted if the program
        is not going to be frozen to produce an executable.    _fixup_main_from_path(data['init_main_from_path'])

  File "/Users/christopherchang/miniconda3/envs/facepcs/lib/python3.10/multiprocessing/spawn.py", line 287, in _fixup_main_from_path
    main_content = runpy.run_path(main_path,
  File "/Users/christopherchang/miniconda3/envs/facepcs/lib/python3.10/runpy.py", line 289, in run_path
    self._launch(process_obj)
  File "/Users/christopherchang/miniconda3/envs/facepcs/lib/python3.10/multiprocessing/popen_spawn_posix.py", line 42, in _launch
    prep_data = spawn.get_preparation_data(process_obj._name)
  File "/Users/christopherchang/miniconda3/envs/facepcs/lib/python3.10/multiprocessing/spawn.py", line 154, in get_preparation_data
    return Popen(process_obj)
  File "/Users/christopherchang/miniconda3/envs/facepcs/lib/python3.10/multiprocessing/popen_spawn_posix.py", line 32, in __init__
    _check_not_importing_main()
  File "/Users/christopherchang/miniconda3/envs/facepcs/lib/python3.10/multiprocessing/spawn.py", line 134, in _check_not_importing_main
    main_content = runpy.run_path(main_path,
    return _run_module_code(code, init_globals, run_name,
  File "/Users/christopherchang/miniconda3/envs/facepcs/lib/python3.10/runpy.py", line 96, in _run_module_code
  File "/Users/christopherchang/miniconda3/envs/facepcs/lib/python3.10/runpy.py", line 289, in run_path
    prep_data = spawn.get_preparation_data(process_obj._name)
  File "/Users/christopherchang/miniconda3/envs/facepcs/lib/python3.10/multiprocessing/spawn.py", line 154, in get_preparation_data
    raise RuntimeError('''
RuntimeError: 
        An attempt has been made to start a new process before the
        current process has finished its bootstrapping phase.

        This probably means that you are not using fork to start your
        child processes and you have forgotten to use the proper idiom
        in the main module:

            if __name__ == '__main__':
                freeze_support()
                ...

        The "freeze_support()" line can be omitted if the program
        is not going to be frozen to produce an executable.
    _check_not_importing_main()
  File "/Users/christopherchang/miniconda3/envs/facepcs/lib/python3.10/multiprocessing/spawn.py", line 134, in _check_not_importing_main
    super().__init__(process_obj)
  File "/Users/christopherchang/miniconda3/envs/facepcs/lib/python3.10/multiprocessing/popen_fork.py", line 19, in __init__
    _run_code(code, mod_globals, init_globals,
  File "/Users/christopherchang/miniconda3/envs/facepcs/lib/python3.10/runpy.py", line 86, in _run_code
    _check_not_importing_main()
    self._launch(process_obj)
  File "/Users/christopherchang/miniconda3/envs/facepcs/lib/python3.10/multiprocessing/spawn.py", line 134, in _check_not_importing_main
  File "/Users/christopherchang/miniconda3/envs/facepcs/lib/python3.10/multiprocessing/popen_spawn_posix.py", line 42, in _launch
    raise RuntimeError('''
RuntimeError: 
        An attempt has been made to start a new process before the
        current process has finished its bootstrapping phase.

        This probably means that you are not using fork to start your
        child processes and you have forgotten to use the proper idiom
        in the main module:

            if __name__ == '__main__':
                freeze_support()
                ...

        The "freeze_support()" line can be omitted if the program
        is not going to be frozen to produce an executable.
    return _run_module_code(code, init_globals, run_name,
  File "/Users/christopherchang/miniconda3/envs/facepcs/lib/python3.10/runpy.py", line 96, in _run_module_code
    exec(code, run_globals)
    prep_data = spawn.get_preparation_data(process_obj._name)
  File "/Users/christopherchang/miniconda3/envs/facepcs/lib/python3.10/multiprocessing/spawn.py", line 154, in get_preparation_data
  File "/Users/christopherchang/TEST/python_test/test.py", line 8, in <module>
    raise RuntimeError('''
RuntimeError: 
        An attempt has been made to start a new process before the
        current process has finished its bootstrapping phase.

        This probably means that you are not using fork to start your
        child processes and you have forgotten to use the proper idiom
        in the main module:

            if __name__ == '__main__':
                freeze_support()
                ...

        The "freeze_support()" line can be omitted if the program
        is not going to be frozen to produce an executable.
    _run_code(code, mod_globals, init_globals,
  File "/Users/christopherchang/miniconda3/envs/facepcs/lib/python3.10/runpy.py", line 86, in _run_code
    exec(code, run_globals)
    multi_process()
  File "/Users/christopherchang/TEST/python_test/test.py", line 7, in multi_process
  File "/Users/christopherchang/TEST/python_test/test.py", line 8, in <module>
    _check_not_importing_main()
  File "/Users/christopherchang/miniconda3/envs/facepcs/lib/python3.10/multiprocessing/spawn.py", line 134, in _check_not_importing_main
    executor.submit(tapo.SessionProcess, i) 
  File "/Users/christopherchang/miniconda3/envs/facepcs/lib/python3.10/concurrent/futures/process.py", line 737, in submit
/Users/christopherchang/miniconda3/envs/facepcs/lib/python3.10/multiprocessing/resource_tracker.py:224: UserWarning: resource_tracker: There appear to be 15 leaked semaphore objects to clean up at shutdown
  warnings.warn('resource_tracker: There appear to be %d '

---

Un-comment # multi_process() and comment the codes below it. Run python test.py.

tapo.py:

from pytutils.mappings import ProcessLocal
plocal = ProcessLocal()
def PRINT():
    print(plocal.userName)  
def SessionProcess(userName_in):
    plocal.userName = userName_in
    print(plocal.userName) 
    PRINT() 

test.py:

import concurrent.futures
import tapo

def multi_process(): 
    with concurrent.futures.ProcessPoolExecutor(max_workers=10) as executor: 
        for i in range(10): 
            executor.submit(tapo.SessionProcess, i) 
# multi_process()

import multiprocessing as mp

def task(num):
  print('This is Process: ', num)

if __name__=='__main__':
  num_process = 5
  process_list = []
  for i in range(num_process):
    process_list.append(mp.Process(target = tapo.SessionProcess, args = (i,)))
    process_list[i].start()

  for i in range(num_process):
    process_list[i].join()