bw2io.errors.MultiprocessingError

[HeinzStuecke]

Hello everyone, today I ran into a "Multiprocessing" error with Brightway.

First, I created a conda environment. conda create --name brightway-env python=3.9

Next, I installed Brightway and PyPardiso.

`pip install brightway2`
`pip install pypardiso`

I then set up Brightway and tried to import the ecoinvent database.

"""Get started with Brightway."""

import brightway2 as bw2data
import bw2analyzer as bwa

# %% Set-up Brightway

bw_project_name = 'my-project'

# If a project with the `bw_project_name` does not exist yet
if bw_project_name not in bw2data.projects:

    bw2data.projects.set_current(bw_project_name)
    bw2data.bw2setup()  # Add elementary flows and LCIA methods

# Import/write ecoinvent database

bw2data.projects.set_current(bw_project_name)

bw_db_name = "ecoinvent39cutoff"

# If a database with the name `bw_db:_name` does not exist yet
if bw_db_name not in bw2data.databases:

    ei = bw2data.SingleOutputEcospold2Importer(
        "./data/ecoinvent-3.9/datasets/",  # Database files
        bw_db_name  # Database name
        )

    ei.apply_strategies()
    ei.statistics()
    ei.write_database()

    print(bw2data.projects)   # Show projects
    print(bw2data.databases)  # Show databases

db_ei39 = bw2data.Database(bw_db_name)  # Load ecoinvent database

del bw_db_name, bw_project_name  # Clear the clutter

Howeber, this yielded the following error:

bw2io.errors.MultiprocessingError: Multiprocessing error; re-run using `use_mp=False`
Traceback (most recent call last):
  File "C:\Users\jtesc\anaconda3\envs\brightway-env\lib\site-packages\bw2io\importers\ecospold2.py", line 71, in __init__
    self.data = extractor.extract(dirpath, db_name, use_mp=use_mp)
  File "C:\Users\jtesc\anaconda3\envs\brightway-env\lib\site-packages\bw2io\extractors\ecospold2.py", line 78, in extract
    with multiprocessing.Pool(processes=multiprocessing.cpu_count()) as pool:
  File "C:\Users\jtesc\anaconda3\envs\brightway-env\lib\multiprocessing\context.py", line 119, in Pool
    return Pool(processes, initializer, initargs, maxtasksperchild,
  File "C:\Users\jtesc\anaconda3\envs\brightway-env\lib\multiprocessing\pool.py", line 212, in __init__
    self._repopulate_pool()
  File "C:\Users\jtesc\anaconda3\envs\brightway-env\lib\multiprocessing\pool.py", line 303, in _repopulate_pool
    return self._repopulate_pool_static(self._ctx, self.Process,
  File "C:\Users\jtesc\anaconda3\envs\brightway-env\lib\multiprocessing\pool.py", line 326, in _repopulate_pool_static
    w.start()
  File "C:\Users\jtesc\anaconda3\envs\brightway-env\lib\multiprocessing\process.py", line 121, in start
Traceback (most recent call last):
  File "C:\Users\jtesc\anaconda3\envs\brightway-env\lib\site-packages\bw2io\importers\ecospold2.py", line 71, in __init__
    self._popen = self._Popen(self)
  File "C:\Users\jtesc\anaconda3\envs\brightway-env\lib\multiprocessing\context.py", line 327, in _Popen
    return Popen(process_obj)
  File "C:\Users\jtesc\anaconda3\envs\brightway-env\lib\multiprocessing\popen_spawn_win32.py", line 45, in __init__
    self.data = extractor.extract(dirpath, db_name, use_mp=use_mp)
  File "C:\Users\jtesc\anaconda3\envs\brightway-env\lib\site-packages\bw2io\extractors\ecospold2.py", line 78, in extract
    prep_data = spawn.get_preparation_data(process_obj._name)
  File "C:\Users\jtesc\anaconda3\envs\brightway-env\lib\multiprocessing\spawn.py", line 154, in get_preparation_data
    with multiprocessing.Pool(processes=multiprocessing.cpu_count()) as pool:
  File "C:\Users\jtesc\anaconda3\envs\brightway-env\lib\multiprocessing\context.py", line 119, in Pool
    _check_not_importing_main()
  File "C:\Users\jtesc\anaconda3\envs\brightway-env\lib\multiprocessing\spawn.py", line 134, in _check_not_importing_main
    return Pool(processes, initializer, initargs, maxtasksperchild,
  File "C:\Users\jtesc\anaconda3\envs\brightway-env\lib\multiprocessing\pool.py", line 212, in __init__
    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.
During handling of the above exception, another exception occurred:
Traceback (most recent call last):
  File "<string>", line 1, in <module>
    self._repopulate_pool()
  File "C:\Users\jtesc\anaconda3\envs\brightway-env\lib\multiprocessing\pool.py", line 303, in _repopulate_pool
  File "C:\Users\jtesc\anaconda3\envs\brightway-env\lib\multiprocessing\spawn.py", line 116, in spawn_main
    return self._repopulate_pool_static(self._ctx, self.Process,
  File "C:\Users\jtesc\anaconda3\envs\brightway-env\lib\multiprocessing\pool.py", line 326, in _repopulate_pool_static
    exitcode = _main(fd, parent_sentinel)
  File "C:\Users\jtesc\anaconda3\envs\brightway-env\lib\multiprocessing\spawn.py", line 125, in _main
    w.start()
  File "C:\Users\jtesc\anaconda3\envs\brightway-env\lib\multiprocessing\process.py", line 121, in start
    prepare(preparation_data)
  File "C:\Users\jtesc\anaconda3\envs\brightway-env\lib\multiprocessing\spawn.py", line 236, in prepare
    self._popen = self._Popen(self)
  File "C:\Users\jtesc\anaconda3\envs\brightway-env\lib\multiprocessing\context.py", line 327, in _Popen
    _fixup_main_from_path(data['init_main_from_path'])
  File "C:\Users\jtesc\anaconda3\envs\brightway-env\lib\multiprocessing\spawn.py", line 287, in _fixup_main_from_path
    return Popen(process_obj)
  File "C:\Users\jtesc\anaconda3\envs\brightway-env\lib\multiprocessing\popen_spawn_win32.py", line 45, in __init__
    main_content = runpy.run_path(main_path,
  File "C:\Users\jtesc\anaconda3\envs\brightway-env\lib\runpy.py", line 288, in run_path
    prep_data = spawn.get_preparation_data(process_obj._name)
  File "C:\Users\jtesc\anaconda3\envs\brightway-env\lib\multiprocessing\spawn.py", line 154, in get_preparation_data
    return _run_module_code(code, init_globals, run_name,
  File "C:\Users\jtesc\anaconda3\envs\brightway-env\lib\runpy.py", line 97, in _run_module_code
    _check_not_importing_main()
  File "C:\Users\jtesc\anaconda3\envs\brightway-env\lib\multiprocessing\spawn.py", line 134, in _check_not_importing_main
    _run_code(code, mod_globals, init_globals,
  File "C:\Users\jtesc\anaconda3\envs\brightway-env\lib\runpy.py", line 87, in _run_code
    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.
During handling of the above exception, another exception occurred:
Traceback (most recent call last):
  File "<string>", line 1, in <module>
    exec(code, run_globals)
  File "c:\users\jtesc\onedrive\01_johanna\01_uni\01_bachelorarbeit\brightway2\firststep.py", line 28, in <module>
    ei = bw2data.SingleOutputEcospold2Importer(
  File "C:\Users\jtesc\anaconda3\envs\brightway-env\lib\site-packages\bw2io\importers\ecospold2.py", line 73, in __init__
  File "C:\Users\jtesc\anaconda3\envs\brightway-env\lib\multiprocessing\spawn.py", line 116, in spawn_main
    raise MultiprocessingError(
  File "C:\Users\jtesc\anaconda3\envs\brightway-env\lib\site-packages\bw2io\importers\ecospold2.py", line 71, in __init__
    self.data = extractor.extract(dirpath, db_name, use_mp=use_mp)
  File "C:\Users\jtesc\anaconda3\envs\brightway-env\lib\site-packages\bw2io\extractors\ecospold2.py", line 78, in extract
    exitcode = _main(fd, parent_sentinel)
  File "C:\Users\jtesc\anaconda3\envs\brightway-env\lib\multiprocessing\spawn.py", line 125, in _main
    with multiprocessing.Pool(processes=multiprocessing.cpu_count()) as pool:
  File "C:\Users\jtesc\anaconda3\envs\brightway-env\lib\multiprocessing\context.py", line 119, in Pool
    return Pool(processes, initializer, initargs, maxtasksperchild,
  File "C:\Users\jtesc\anaconda3\envs\brightway-env\lib\multiprocessing\pool.py", line 212, in __init__
    prepare(preparation_data)
  File "C:\Users\jtesc\anaconda3\envs\brightway-env\lib\multiprocessing\spawn.py", line 236, in prepare
    self._repopulate_pool()
  File "C:\Users\jtesc\anaconda3\envs\brightway-env\lib\multiprocessing\pool.py", line 303, in _repopulate_pool
    return self._repopulate_pool_static(self._ctx, self.Process,
  File "C:\Users\jtesc\anaconda3\envs\brightway-env\lib\multiprocessing\pool.py", line 326, in _repopulate_pool_static
    _fixup_main_from_path(data['init_main_from_path'])
  File "C:\Users\jtesc\anaconda3\envs\brightway-env\lib\multiprocessing\spawn.py", line 287, in _fixup_main_from_path
    w.start()
  File "C:\Users\jtesc\anaconda3\envs\brightway-env\lib\multiprocessing\process.py", line 121, in start
    self._popen = self._Popen(self)
  File "C:\Users\jtesc\anaconda3\envs\brightway-env\lib\multiprocessing\context.py", line 327, in _Popen
    main_content = runpy.run_path(main_path,
  File "C:\Users\jtesc\anaconda3\envs\brightway-env\lib\runpy.py", line 288, in run_path
    return Popen(process_obj)
  File "C:\Users\jtesc\anaconda3\envs\brightway-env\lib\multiprocessing\popen_spawn_win32.py", line 45, in __init__
    return _run_module_code(code, init_globals, run_name,
  File "C:\Users\jtesc\anaconda3\envs\brightway-env\lib\runpy.py", line 97, in _run_module_code
    prep_data = spawn.get_preparation_data(process_obj._name)
  File "C:\Users\jtesc\anaconda3\envs\brightway-env\lib\multiprocessing\spawn.py", line 154, in get_preparation_data
    _check_not_importing_main()
  File "C:\Users\jtesc\anaconda3\envs\brightway-env\lib\multiprocessing\spawn.py", line 134, in _check_not_importing_main
    _run_code(code, mod_globals, init_globals,
  File "C:\Users\jtesc\anaconda3\envs\brightway-env\lib\runpy.py", line 87, in _run_code
    raise RuntimeError('''
bw2io.errors.MultiprocessingError: Multiprocessing error; re-run using `use_mp=False`
    exec(code, run_globals)
  File "c:\users\jtesc\onedrive\01_johanna\01_uni\01_bachelorarbeit\brightway2\firststep.py", line 28, in <module>
    ei = bw2data.SingleOutputEcospold2Importer(
  File "C:\Users\jtesc\anaconda3\envs\brightway-env\lib\site-packages\bw2io\importers\ecospold2.py", line 73, in __init__
    raise MultiprocessingError(
  File "C:\Users\jtesc\anaconda3\envs\brightway-env\lib\site-packages\bw2io\importers\ecospold2.py", line 71, in __init__
    self.data = extractor.extract(dirpath, db_name, use_mp=use_mp)
  File "C:\Users\jtesc\anaconda3\envs\brightway-env\lib\site-packages\bw2io\extractors\ecospold2.py", line 78, in extract
    with multiprocessing.Pool(processes=multiprocessing.cpu_count()) as pool:
  File "C:\Users\jtesc\anaconda3\envs\brightway-env\lib\multiprocessing\context.py", line 119, in Pool
    return Pool(processes, initializer, initargs, maxtasksperchild,
  File "C:\Users\jtesc\anaconda3\envs\brightway-env\lib\multiprocessing\pool.py", line 212, in __init__
    self._repopulate_pool()
  File "C:\Users\jtesc\anaconda3\envs\brightway-env\lib\multiprocessing\pool.py", line 303, in _repopulate_pool
    return self._repopulate_pool_static(self._ctx, self.Process,
  File "C:\Users\jtesc\anaconda3\envs\brightway-env\lib\multiprocessing\pool.py", line 326, in _repopulate_pool_static
    w.start()
  File "C:\Users\jtesc\anaconda3\envs\brightway-env\lib\multiprocessing\process.py", line 121, in start
    self._popen = self._Popen(self)
  File "C:\Users\jtesc\anaconda3\envs\brightway-env\lib\multiprocessing\context.py", line 327, in _Popen
    return Popen(process_obj)
  File "C:\Users\jtesc\anaconda3\envs\brightway-env\lib\multiprocessing\popen_spawn_win32.py", line 45, in __init__
    prep_data = spawn.get_preparation_data(process_obj._name)
  File "C:\Users\jtesc\anaconda3\envs\brightway-env\lib\multiprocessing\spawn.py", line 154, in get_preparation_data
    _check_not_importing_main()
  File "C:\Users\jtesc\anaconda3\envs\brightway-env\lib\multiprocessing\spawn.py", line 134, in _check_not_importing_main
    raise RuntimeError('''
bw2io.errors.MultiprocessingError: Multiprocessing error; re-run using `use_mp=False`
Traceback (most recent call last):
  File "C:\Users\jtesc\anaconda3\envs\brightway-env\lib\site-packages\bw2io\importers\ecospold2.py", line 71, in __init__
    self.data = extractor.extract(dirpath, db_name, use_mp=use_mp)
  File "C:\Users\jtesc\anaconda3\envs\brightway-env\lib\site-packages\bw2io\extractors\ecospold2.py", line 78, in extract
    with multiprocessing.Pool(processes=multiprocessing.cpu_count()) as pool:
  File "C:\Users\jtesc\anaconda3\envs\brightway-env\lib\multiprocessing\context.py", line 119, in Pool
    return Pool(processes, initializer, initargs, maxtasksperchild,
  File "C:\Users\jtesc\anaconda3\envs\brightway-env\lib\multiprocessing\pool.py", line 212, in __init__
    self._repopulate_pool()
  File "C:\Users\jtesc\anaconda3\envs\brightway-env\lib\multiprocessing\pool.py", line 303, in _repopulate_pool
    return self._repopulate_pool_static(self._ctx, self.Process,
  File "C:\Users\jtesc\anaconda3\envs\brightway-env\lib\multiprocessing\pool.py", line 326, in _repopulate_pool_static
    w.start()
  File "C:\Users\jtesc\anaconda3\envs\brightway-env\lib\multiprocessing\process.py", line 121, in start
    self._popen = self._Popen(self)
  File "C:\Users\jtesc\anaconda3\envs\brightway-env\lib\multiprocessing\context.py", line 327, in _Popen
    return Popen(process_obj)
  File "C:\Users\jtesc\anaconda3\envs\brightway-env\lib\multiprocessing\popen_spawn_win32.py", line 45, in __init__
    prep_data = spawn.get_preparation_data(process_obj._name)
  File "C:\Users\jtesc\anaconda3\envs\brightway-env\lib\multiprocessing\spawn.py", line 154, in get_preparation_data
    _check_not_importing_main()
  File "C:\Users\jtesc\anaconda3\envs\brightway-env\lib\multiprocessing\spawn.py", line 134, in _check_not_importing_main
    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.
During handling of the above exception, another exception occurred:
Traceback (most recent call last):
  File "<string>", line 1, in <module>
  File "C:\Users\jtesc\anaconda3\envs\brightway-env\lib\multiprocessing\spawn.py", line 116, in spawn_main
    exitcode = _main(fd, parent_sentinel)
  File "C:\Users\jtesc\anaconda3\envs\brightway-env\lib\multiprocessing\spawn.py", line 125, in _main
    prepare(preparation_data)
  File "C:\Users\jtesc\anaconda3\envs\brightway-env\lib\multiprocessing\spawn.py", line 236, in prepare
    _fixup_main_from_path(data['init_main_from_path'])
  File "C:\Users\jtesc\anaconda3\envs\brightway-env\lib\multiprocessing\spawn.py", line 287, in _fixup_main_from_path
    main_content = runpy.run_path(main_path,
  File "C:\Users\jtesc\anaconda3\envs\brightway-env\lib\runpy.py", line 288, in run_path
    return _run_module_code(code, init_globals, run_name,
  File "C:\Users\jtesc\anaconda3\envs\brightway-env\lib\runpy.py", line 97, in _run_module_code
    _run_code(code, mod_globals, init_globals,
  File "C:\Users\jtesc\anaconda3\envs\brightway-env\lib\runpy.py", line 87, in _run_code
    exec(code, run_globals)
  File "c:\users\jtesc\onedrive\01_johanna\01_uni\01_bachelorarbeit\brightway2\firststep.py", line 28, in <module>
Traceback (most recent call last):
  File "C:\Users\jtesc\anaconda3\envs\brightway-env\lib\site-packages\bw2io\importers\ecospold2.py", line 71, in __init__
    ei = bw2data.SingleOutputEcospold2Importer(
  File "C:\Users\jtesc\anaconda3\envs\brightway-env\lib\site-packages\bw2io\importers\ecospold2.py", line 73, in __init__
    self.data = extractor.extract(dirpath, db_name, use_mp=use_mp)
  File "C:\Users\jtesc\anaconda3\envs\brightway-env\lib\site-packages\bw2io\extractors\ecospold2.py", line 78, in extract
    raise MultiprocessingError(
  File "C:\Users\jtesc\anaconda3\envs\brightway-env\lib\site-packages\bw2io\importers\ecospold2.py", line 71, in __init__
    with multiprocessing.Pool(processes=multiprocessing.cpu_count()) as pool:
  File "C:\Users\jtesc\anaconda3\envs\brightway-env\lib\multiprocessing\context.py", line 119, in Pool
    self.data = extractor.extract(dirpath, db_name, use_mp=use_mp)
  File "C:\Users\jtesc\anaconda3\envs\brightway-env\lib\site-packages\bw2io\extractors\ecospold2.py", line 78, in extract
    return Pool(processes, initializer, initargs, maxtasksperchild,
    with multiprocessing.Pool(processes=multiprocessing.cpu_count()) as pool:
  File "C:\Users\jtesc\anaconda3\envs\brightway-env\lib\multiprocessing\pool.py", line 212, in __init__
  File "C:\Users\jtesc\anaconda3\envs\brightway-env\lib\multiprocessing\context.py", line 119, in Pool
    self._repopulate_pool()
  File "C:\Users\jtesc\anaconda3\envs\brightway-env\lib\multiprocessing\pool.py", line 303, in _repopulate_pool
    return Pool(processes, initializer, initargs, maxtasksperchild,
  File "C:\Users\jtesc\anaconda3\envs\brightway-env\lib\multiprocessing\pool.py", line 212, in __init__
    return self._repopulate_pool_static(self._ctx, self.Process,
  File "C:\Users\jtesc\anaconda3\envs\brightway-env\lib\multiprocessing\pool.py", line 326, in _repopulate_pool_static
    self._repopulate_pool()
  File "C:\Users\jtesc\anaconda3\envs\brightway-env\lib\multiprocessing\pool.py", line 303, in _repopulate_pool
    w.start()
  File "C:\Users\jtesc\anaconda3\envs\brightway-env\lib\multiprocessing\process.py", line 121, in start
    return self._repopulate_pool_static(self._ctx, self.Process,
  File "C:\Users\jtesc\anaconda3\envs\brightway-env\lib\multiprocessing\pool.py", line 326, in _repopulate_pool_static
    self._popen = self._Popen(self)
  File "C:\Users\jtesc\anaconda3\envs\brightway-env\lib\multiprocessing\context.py", line 327, in _Popen
    w.start()
  File "C:\Users\jtesc\anaconda3\envs\brightway-env\lib\multiprocessing\process.py", line 121, in start
    self._popen = self._Popen(self)
  File "C:\Users\jtesc\anaconda3\envs\brightway-env\lib\multiprocessing\context.py", line 327, in _Popen
    return Popen(process_obj)
  File "C:\Users\jtesc\anaconda3\envs\brightway-env\lib\multiprocessing\popen_spawn_win32.py", line 45, in __init__
    return Popen(process_obj)
  File "C:\Users\jtesc\anaconda3\envs\brightway-env\lib\multiprocessing\popen_spawn_win32.py", line 45, in __init__
    prep_data = spawn.get_preparation_data(process_obj._name)
  File "C:\Users\jtesc\anaconda3\envs\brightway-env\lib\multiprocessing\spawn.py", line 154, in get_preparation_data
    prep_data = spawn.get_preparation_data(process_obj._name)
  File "C:\Users\jtesc\anaconda3\envs\brightway-env\lib\multiprocessing\spawn.py", line 154, in get_preparation_data
    _check_not_importing_main()
  File "C:\Users\jtesc\anaconda3\envs\brightway-env\lib\multiprocessing\spawn.py", line 134, in _check_not_importing_main
    _check_not_importing_main()
  File "C:\Users\jtesc\anaconda3\envs\brightway-env\lib\multiprocessing\spawn.py", line 134, in _check_not_importing_main
    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.
During handling of the above exception, another exception occurred:
Traceback (most recent call last):
  File "<string>", line 1, in <module>
  File "C:\Users\jtesc\anaconda3\envs\brightway-env\lib\multiprocessing\spawn.py", line 116, in spawn_main
    raise RuntimeError('''
bw2io.errors.MultiprocessingError: Multiprocessing error; re-run using `use_mp=False`
    exitcode = _main(fd, parent_sentinel)
  File "C:\Users\jtesc\anaconda3\envs\brightway-env\lib\multiprocessing\spawn.py", line 125, in _main
    prepare(preparation_data)
  File "C:\Users\jtesc\anaconda3\envs\brightway-env\lib\multiprocessing\spawn.py", line 236, in prepare
    _fixup_main_from_path(data['init_main_from_path'])
  File "C:\Users\jtesc\anaconda3\envs\brightway-env\lib\multiprocessing\spawn.py", line 287, in _fixup_main_from_path
    main_content = runpy.run_path(main_path,
  File "C:\Users\jtesc\anaconda3\envs\brightway-env\lib\runpy.py", line 288, in run_path
    return _run_module_code(code, init_globals, run_name,
  File "C:\Users\jtesc\anaconda3\envs\brightway-env\lib\runpy.py", line 97, in _run_module_code
    _run_code(code, mod_globals, init_globals,
  File "C:\Users\jtesc\anaconda3\envs\brightway-env\lib\runpy.py", line 87, in _run_code
    exec(code, run_globals)
  File "c:\users\jtesc\onedrive\01_johanna\01_uni\01_bachelorarbeit\brightway2\firststep.py", line 28, in <module>
    ei = bw2data.SingleOutputEcospold2Importer(
  File "C:\Users\jtesc\anaconda3\envs\brightway-env\lib\site-packages\bw2io\importers\ecospold2.py", line 73, in __init__
    raise MultiprocessingError(
  File "C:\Users\jtesc\anaconda3\envs\brightway-env\lib\site-packages\bw2io\importers\ecospold2.py", line 71, in __init__
    self.data = extractor.extract(dirpath, db_name, use_mp=use_mp)
  File "C:\Users\jtesc\anaconda3\envs\brightway-env\lib\site-packages\bw2io\extractors\ecospold2.py", line 78, in extract
Traceback (most recent call last):
  File "C:\Users\jtesc\anaconda3\envs\brightway-env\lib\site-packages\bw2io\importers\ecospold2.py", line 71, in __init__
    with multiprocessing.Pool(processes=multiprocessing.cpu_count()) as pool:
  File "C:\Users\jtesc\anaconda3\envs\brightway-env\lib\multiprocessing\context.py", line 119, in Pool
    return Pool(processes, initializer, initargs, maxtasksperchild,
  File "C:\Users\jtesc\anaconda3\envs\brightway-env\lib\multiprocessing\pool.py", line 212, in __init__
    self._repopulate_pool()
  File "C:\Users\jtesc\anaconda3\envs\brightway-env\lib\multiprocessing\pool.py", line 303, in _repopulate_pool
    self.data = extractor.extract(dirpath, db_name, use_mp=use_mp)
  File "C:\Users\jtesc\anaconda3\envs\brightway-env\lib\site-packages\bw2io\extractors\ecospold2.py", line 78, in extract
    return self._repopulate_pool_static(self._ctx, self.Process,
  File "C:\Users\jtesc\anaconda3\envs\brightway-env\lib\multiprocessing\pool.py", line 326, in _repopulate_pool_static
    w.start()
  File "C:\Users\jtesc\anaconda3\envs\brightway-env\lib\multiprocessing\process.py", line 121, in start
    with multiprocessing.Pool(processes=multiprocessing.cpu_count()) as pool:
  File "C:\Users\jtesc\anaconda3\envs\brightway-env\lib\multiprocessing\context.py", line 119, in Pool
    self._popen = self._Popen(self)
  File "C:\Users\jtesc\anaconda3\envs\brightway-env\lib\multiprocessing\context.py", line 327, in _Popen
    return Pool(processes, initializer, initargs, maxtasksperchild,
  File "C:\Users\jtesc\anaconda3\envs\brightway-env\lib\multiprocessing\pool.py", line 212, in __init__
    return Popen(process_obj)
  File "C:\Users\jtesc\anaconda3\envs\brightway-env\lib\multiprocessing\popen_spawn_win32.py", line 45, in __init__
    prep_data = spawn.get_preparation_data(process_obj._name)
  File "C:\Users\jtesc\anaconda3\envs\brightway-env\lib\multiprocessing\spawn.py", line 154, in get_preparation_data
    _check_not_importing_main()
  File "C:\Users\jtesc\anaconda3\envs\brightway-env\lib\multiprocessing\spawn.py", line 134, in _check_not_importing_main
    raise RuntimeError('''
bw2io.errors.MultiprocessingError: Multiprocessing error; re-run using `use_mp=False`
    self._repopulate_pool()
  File "C:\Users\jtesc\anaconda3\envs\brightway-env\lib\multiprocessing\pool.py", line 303, in _repopulate_pool
    return self._repopulate_pool_static(self._ctx, self.Process,
  File "C:\Users\jtesc\anaconda3\envs\brightway-env\lib\multiprocessing\pool.py", line 326, in _repopulate_pool_static
    w.start()
  File "C:\Users\jtesc\anaconda3\envs\brightway-env\lib\multiprocessing\process.py", line 121, in start
    self._popen = self._Popen(self)
  File "C:\Users\jtesc\anaconda3\envs\brightway-env\lib\multiprocessing\context.py", line 327, in _Popen
    return Popen(process_obj)
  File "C:\Users\jtesc\anaconda3\envs\brightway-env\lib\multiprocessing\popen_spawn_win32.py", line 45, in __init__
Traceback (most recent call last):
  File "C:\Users\jtesc\anaconda3\envs\brightway-env\lib\site-packages\bw2io\importers\ecospold2.py", line 71, in __init__
    self.data = extractor.extract(dirpath, db_name, use_mp=use_mp)
  File "C:\Users\jtesc\anaconda3\envs\brightway-env\lib\site-packages\bw2io\extractors\ecospold2.py", line 78, in extract
    prep_data = spawn.get_preparation_data(process_obj._name)
  File "C:\Users\jtesc\anaconda3\envs\brightway-env\lib\multiprocessing\spawn.py", line 154, in get_preparation_data
    with multiprocessing.Pool(processes=multiprocessing.cpu_count()) as pool:
  File "C:\Users\jtesc\anaconda3\envs\brightway-env\lib\multiprocessing\context.py", line 119, in Pool
    return Pool(processes, initializer, initargs, maxtasksperchild,
  File "C:\Users\jtesc\anaconda3\envs\brightway-env\lib\multiprocessing\pool.py", line 212, in __init__
    _check_not_importing_main()
  File "C:\Users\jtesc\anaconda3\envs\brightway-env\lib\multiprocessing\spawn.py", line 134, in _check_not_importing_main
    self._repopulate_pool()
  File "C:\Users\jtesc\anaconda3\envs\brightway-env\lib\multiprocessing\pool.py", line 303, in _repopulate_pool
    return self._repopulate_pool_static(self._ctx, self.Process,
  File "C:\Users\jtesc\anaconda3\envs\brightway-env\lib\multiprocessing\pool.py", line 326, in _repopulate_pool_static
    w.start()
  File "C:\Users\jtesc\anaconda3\envs\brightway-env\lib\multiprocessing\process.py", line 121, in start
    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.
During handling of the above exception, another exception occurred:
Traceback (most recent call last):
  File "<string>", line 1, in <module>
    self._popen = self._Popen(self)
  File "C:\Users\jtesc\anaconda3\envs\brightway-env\lib\multiprocessing\context.py", line 327, in _Popen
  File "C:\Users\jtesc\anaconda3\envs\brightway-env\lib\multiprocessing\spawn.py", line 116, in spawn_main
    return Popen(process_obj)
  File "C:\Users\jtesc\anaconda3\envs\brightway-env\lib\multiprocessing\popen_spawn_win32.py", line 45, in __init__
    exitcode = _main(fd, parent_sentinel)
  File "C:\Users\jtesc\anaconda3\envs\brightway-env\lib\multiprocessing\spawn.py", line 125, in _main
    prep_data = spawn.get_preparation_data(process_obj._name)
  File "C:\Users\jtesc\anaconda3\envs\brightway-env\lib\multiprocessing\spawn.py", line 154, in get_preparation_data
    prepare(preparation_data)
  File "C:\Users\jtesc\anaconda3\envs\brightway-env\lib\multiprocessing\spawn.py", line 236, in prepare
    _check_not_importing_main()
  File "C:\Users\jtesc\anaconda3\envs\brightway-env\lib\multiprocessing\spawn.py", line 134, in _check_not_importing_main
    _fixup_main_from_path(data['init_main_from_path'])
  File "C:\Users\jtesc\anaconda3\envs\brightway-env\lib\multiprocessing\spawn.py", line 287, in _fixup_main_from_path
    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.
During handling of the above exception, another exception occurred:
Traceback (most recent call last):
  File "<string>", line 1, in <module>
    main_content = runpy.run_path(main_path,
  File "C:\Users\jtesc\anaconda3\envs\brightway-env\lib\runpy.py", line 288, in run_path
  File "C:\Users\jtesc\anaconda3\envs\brightway-env\lib\multiprocessing\spawn.py", line 116, in spawn_main
    exitcode = _main(fd, parent_sentinel)
  File "C:\Users\jtesc\anaconda3\envs\brightway-env\lib\multiprocessing\spawn.py", line 125, in _main
    return _run_module_code(code, init_globals, run_name,
  File "C:\Users\jtesc\anaconda3\envs\brightway-env\lib\runpy.py", line 97, in _run_module_code
    prepare(preparation_data)
  File "C:\Users\jtesc\anaconda3\envs\brightway-env\lib\multiprocessing\spawn.py", line 236, in prepare
    _run_code(code, mod_globals, init_globals,
  File "C:\Users\jtesc\anaconda3\envs\brightway-env\lib\runpy.py", line 87, in _run_code
    _fixup_main_from_path(data['init_main_from_path'])
  File "C:\Users\jtesc\anaconda3\envs\brightway-env\lib\multiprocessing\spawn.py", line 287, in _fixup_main_from_path
    main_content = runpy.run_path(main_path,
  File "C:\Users\jtesc\anaconda3\envs\brightway-env\lib\runpy.py", line 288, in run_path
    exec(code, run_globals)
  File "c:\users\jtesc\onedrive\01_johanna\01_uni\01_bachelorarbeit\brightway2\firststep.py", line 28, in <module>
    return _run_module_code(code, init_globals, run_name,
  File "C:\Users\jtesc\anaconda3\envs\brightway-env\lib\runpy.py", line 97, in _run_module_code
    ei = bw2data.SingleOutputEcospold2Importer(
  File "C:\Users\jtesc\anaconda3\envs\brightway-env\lib\site-packages\bw2io\importers\ecospold2.py", line 73, in __init__
    _run_code(code, mod_globals, init_globals,
  File "C:\Users\jtesc\anaconda3\envs\brightway-env\lib\runpy.py", line 87, in _run_code
    raise MultiprocessingError(
  File "C:\Users\jtesc\anaconda3\envs\brightway-env\lib\site-packages\bw2io\importers\ecospold2.py", line 71, in __init__
    exec(code, run_globals)
  File "c:\users\jtesc\onedrive\01_johanna\01_uni\01_bachelorarbeit\brightway2\firststep.py", line 28, in <module>
    ei = bw2data.SingleOutputEcospold2Importer(
  File "C:\Users\jtesc\anaconda3\envs\brightway-env\lib\site-packages\bw2io\importers\ecospold2.py", line 73, in __init__
    self.data = extractor.extract(dirpath, db_name, use_mp=use_mp)
  File "C:\Users\jtesc\anaconda3\envs\brightway-env\lib\site-packages\bw2io\extractors\ecospold2.py", line 78, in extract
    raise MultiprocessingError(
  File "C:\Users\jtesc\anaconda3\envs\brightway-env\lib\site-packages\bw2io\importers\ecospold2.py", line 71, in __init__
    self.data = extractor.extract(dirpath, db_name, use_mp=use_mp)
  File "C:\Users\jtesc\anaconda3\envs\brightway-env\lib\site-packages\bw2io\extractors\ecospold2.py", line 78, in extract
    with multiprocessing.Pool(processes=multiprocessing.cpu_count()) as pool:
  File "C:\Users\jtesc\anaconda3\envs\brightway-env\lib\multiprocessing\context.py", line 119, in Pool
    with multiprocessing.Pool(processes=multiprocessing.cpu_count()) as pool:
  File "C:\Users\jtesc\anaconda3\envs\brightway-env\lib\multiprocessing\context.py", line 119, in Pool
    return Pool(processes, initializer, initargs, maxtasksperchild,
  File "C:\Users\jtesc\anaconda3\envs\brightway-env\lib\multiprocessing\pool.py", line 212, in __init__
    return Pool(processes, initializer, initargs, maxtasksperchild,
  File "C:\Users\jtesc\anaconda3\envs\brightway-env\lib\multiprocessing\pool.py", line 212, in __init__
    self._repopulate_pool()
  File "C:\Users\jtesc\anaconda3\envs\brightway-env\lib\multiprocessing\pool.py", line 303, in _repopulate_pool
    self._repopulate_pool()
  File "C:\Users\jtesc\anaconda3\envs\brightway-env\lib\multiprocessing\pool.py", line 303, in _repopulate_pool
    return self._repopulate_pool_static(self._ctx, self.Process,
  File "C:\Users\jtesc\anaconda3\envs\brightway-env\lib\multiprocessing\pool.py", line 326, in _repopulate_pool_static
    w.start()
  File "C:\Users\jtesc\anaconda3\envs\brightway-env\lib\multiprocessing\process.py", line 121, in start
    return self._repopulate_pool_static(self._ctx, self.Process,
  File "C:\Users\jtesc\anaconda3\envs\brightway-env\lib\multiprocessing\pool.py", line 326, in _repopulate_pool_static
    self._popen = self._Popen(self)
  File "C:\Users\jtesc\anaconda3\envs\brightway-env\lib\multiprocessing\context.py", line 327, in _Popen
    w.start()
  File "C:\Users\jtesc\anaconda3\envs\brightway-env\lib\multiprocessing\process.py", line 121, in start
    return Popen(process_obj)
  File "C:\Users\jtesc\anaconda3\envs\brightway-env\lib\multiprocessing\popen_spawn_win32.py", line 45, in __init__
    prep_data = spawn.get_preparation_data(process_obj._name)
  File "C:\Users\jtesc\anaconda3\envs\brightway-env\lib\multiprocessing\spawn.py", line 154, in get_preparation_data
    self._popen = self._Popen(self)
  File "C:\Users\jtesc\anaconda3\envs\brightway-env\lib\multiprocessing\context.py", line 327, in _Popen
    _check_not_importing_main()
  File "C:\Users\jtesc\anaconda3\envs\brightway-env\lib\multiprocessing\spawn.py", line 134, in _check_not_importing_main
    raise RuntimeError('''
bw2io.errors.MultiprocessingError: Multiprocessing error; re-run using `use_mp=False`
    return Popen(process_obj)
  File "C:\Users\jtesc\anaconda3\envs\brightway-env\lib\multiprocessing\popen_spawn_win32.py", line 45, in __init__
    prep_data = spawn.get_preparation_data(process_obj._name)
  File "C:\Users\jtesc\anaconda3\envs\brightway-env\lib\multiprocessing\spawn.py", line 154, in get_preparation_data
    _check_not_importing_main()
  File "C:\Users\jtesc\anaconda3\envs\brightway-env\lib\multiprocessing\spawn.py", line 134, in _check_not_importing_main
    raise RuntimeError('''
bw2io.errors.MultiprocessingError: Multiprocessing error; re-run using `use_mp=False`

Does anyone have an idea what I did wrong?

[Julian-PC]

I have just started using Brightway, and a similar thing happened to me. As suggested by the first line of the error, the resolution was to add use_mp=False to the line which imports the database:

ei = bw2data.SingleOutputEcospold2Importer( "./data/ecoinvent-3.9/datasets/", # Database files bw_db_name, # Database name use_mp=False)

I'm not sure why multi-processing doesn't work on my Brightway / machine, but if I find a solution I will make a post it.