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b1694cf588
This allows different parts of a program to use different methods for starting processes without interfering with each other.
259 lines
7.4 KiB
Python
259 lines
7.4 KiB
Python
#
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# Code used to start processes when using the spawn or forkserver
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# start methods.
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#
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# multiprocessing/spawn.py
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#
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# Copyright (c) 2006-2008, R Oudkerk
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# Licensed to PSF under a Contributor Agreement.
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#
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import os
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import pickle
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import sys
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from . import get_start_method, set_start_method
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from . import process
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from . import util
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__all__ = ['_main', 'freeze_support', 'set_executable', 'get_executable',
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'get_preparation_data', 'get_command_line', 'import_main_path']
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#
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# _python_exe is the assumed path to the python executable.
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# People embedding Python want to modify it.
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#
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if sys.platform != 'win32':
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WINEXE = False
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WINSERVICE = False
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else:
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WINEXE = (sys.platform == 'win32' and getattr(sys, 'frozen', False))
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WINSERVICE = sys.executable.lower().endswith("pythonservice.exe")
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if WINSERVICE:
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_python_exe = os.path.join(sys.exec_prefix, 'python.exe')
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else:
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_python_exe = sys.executable
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def set_executable(exe):
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global _python_exe
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_python_exe = exe
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def get_executable():
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return _python_exe
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#
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#
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#
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def is_forking(argv):
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'''
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Return whether commandline indicates we are forking
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'''
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if len(argv) >= 2 and argv[1] == '--multiprocessing-fork':
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return True
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else:
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return False
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def freeze_support():
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'''
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Run code for process object if this in not the main process
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'''
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if is_forking(sys.argv):
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main()
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sys.exit()
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def get_command_line(**kwds):
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'''
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Returns prefix of command line used for spawning a child process
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'''
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if getattr(sys, 'frozen', False):
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return [sys.executable, '--multiprocessing-fork']
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else:
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prog = 'from multiprocessing.spawn import spawn_main; spawn_main(%s)'
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prog %= ', '.join('%s=%r' % item for item in kwds.items())
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opts = util._args_from_interpreter_flags()
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return [_python_exe] + opts + ['-c', prog, '--multiprocessing-fork']
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def spawn_main(pipe_handle, parent_pid=None, tracker_fd=None):
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'''
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Run code specifed by data received over pipe
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'''
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assert is_forking(sys.argv)
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if sys.platform == 'win32':
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import msvcrt
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from .reduction import steal_handle
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new_handle = steal_handle(parent_pid, pipe_handle)
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fd = msvcrt.open_osfhandle(new_handle, os.O_RDONLY)
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else:
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from . import semaphore_tracker
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semaphore_tracker._semaphore_tracker._fd = tracker_fd
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fd = pipe_handle
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exitcode = _main(fd)
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sys.exit(exitcode)
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def _main(fd):
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with os.fdopen(fd, 'rb', closefd=True) as from_parent:
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process.current_process()._inheriting = True
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try:
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preparation_data = pickle.load(from_parent)
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prepare(preparation_data)
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self = pickle.load(from_parent)
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finally:
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del process.current_process()._inheriting
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return self._bootstrap()
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def _check_not_importing_main():
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if getattr(process.current_process(), '_inheriting', False):
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raise RuntimeError('''
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An attempt has been made to start a new process before the
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current process has finished its bootstrapping phase.
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This probably means that you are not using fork to start your
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child processes and you have forgotten to use the proper idiom
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in the main module:
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if __name__ == '__main__':
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freeze_support()
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...
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The "freeze_support()" line can be omitted if the program
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is not going to be frozen to produce an executable.''')
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def get_preparation_data(name):
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'''
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Return info about parent needed by child to unpickle process object
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'''
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_check_not_importing_main()
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d = dict(
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log_to_stderr=util._log_to_stderr,
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authkey=process.current_process().authkey,
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)
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if util._logger is not None:
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d['log_level'] = util._logger.getEffectiveLevel()
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sys_path=sys.path.copy()
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try:
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i = sys_path.index('')
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except ValueError:
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pass
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else:
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sys_path[i] = process.ORIGINAL_DIR
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d.update(
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name=name,
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sys_path=sys_path,
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sys_argv=sys.argv,
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orig_dir=process.ORIGINAL_DIR,
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dir=os.getcwd(),
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start_method=get_start_method(),
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)
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if sys.platform != 'win32' or (not WINEXE and not WINSERVICE):
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main_path = getattr(sys.modules['__main__'], '__file__', None)
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if not main_path and sys.argv[0] not in ('', '-c'):
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main_path = sys.argv[0]
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if main_path is not None:
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if (not os.path.isabs(main_path) and
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process.ORIGINAL_DIR is not None):
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main_path = os.path.join(process.ORIGINAL_DIR, main_path)
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d['main_path'] = os.path.normpath(main_path)
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return d
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#
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# Prepare current process
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#
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old_main_modules = []
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def prepare(data):
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'''
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Try to get current process ready to unpickle process object
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'''
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if 'name' in data:
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process.current_process().name = data['name']
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if 'authkey' in data:
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process.current_process().authkey = data['authkey']
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if 'log_to_stderr' in data and data['log_to_stderr']:
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util.log_to_stderr()
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if 'log_level' in data:
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util.get_logger().setLevel(data['log_level'])
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if 'sys_path' in data:
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sys.path = data['sys_path']
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if 'sys_argv' in data:
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sys.argv = data['sys_argv']
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if 'dir' in data:
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os.chdir(data['dir'])
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if 'orig_dir' in data:
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process.ORIGINAL_DIR = data['orig_dir']
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if 'start_method' in data:
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set_start_method(data['start_method'])
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if 'main_path' in data:
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import_main_path(data['main_path'])
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def import_main_path(main_path):
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'''
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Set sys.modules['__main__'] to module at main_path
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'''
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# XXX (ncoghlan): The following code makes several bogus
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# assumptions regarding the relationship between __file__
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# and a module's real name. See PEP 302 and issue #10845
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if getattr(sys.modules['__main__'], '__file__', None) == main_path:
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return
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main_name = os.path.splitext(os.path.basename(main_path))[0]
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if main_name == '__init__':
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main_name = os.path.basename(os.path.dirname(main_path))
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if main_name == '__main__':
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main_module = sys.modules['__main__']
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main_module.__file__ = main_path
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elif main_name != 'ipython':
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# Main modules not actually called __main__.py may
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# contain additional code that should still be executed
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import importlib
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import types
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if main_path is None:
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dirs = None
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elif os.path.basename(main_path).startswith('__init__.py'):
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dirs = [os.path.dirname(os.path.dirname(main_path))]
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else:
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dirs = [os.path.dirname(main_path)]
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assert main_name not in sys.modules, main_name
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sys.modules.pop('__mp_main__', None)
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# We should not try to load __main__
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# since that would execute 'if __name__ == "__main__"'
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# clauses, potentially causing a psuedo fork bomb.
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loader = importlib.find_loader(main_name, path=dirs)
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main_module = types.ModuleType(main_name)
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try:
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loader.init_module_attrs(main_module)
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except AttributeError: # init_module_attrs is optional
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pass
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main_module.__name__ = '__mp_main__'
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code = loader.get_code(main_name)
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exec(code, main_module.__dict__)
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old_main_modules.append(sys.modules['__main__'])
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sys.modules['__main__'] = sys.modules['__mp_main__'] = main_module
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