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add the multiprocessing package to fulfill PEP 371
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Benjamin Peterson
parent
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commit
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32 changed files with 12500 additions and 0 deletions
429
Lib/multiprocessing/forking.py
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429
Lib/multiprocessing/forking.py
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#
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# Module for starting a process object using os.fork() or CreateProcess()
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#
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# multiprocessing/forking.py
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#
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# Copyright (c) 2006-2008, R Oudkerk --- see COPYING.txt
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#
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import os
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import sys
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import signal
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from multiprocessing import util, process
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__all__ = ['Popen', 'assert_spawning', 'exit', 'duplicate', 'close']
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#
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# Check that the current thread is spawning a child process
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#
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def assert_spawning(self):
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if not Popen.thread_is_spawning():
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raise RuntimeError(
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'%s objects should only be shared between processes'
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' through inheritance' % type(self).__name__
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)
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#
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# Unix
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#
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if sys.platform != 'win32':
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import time
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exit = os._exit
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duplicate = os.dup
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close = os.close
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#
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# We define a Popen class similar to the one from subprocess, but
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# whose constructor takes a process object as its argument.
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#
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class Popen(object):
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def __init__(self, process_obj):
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sys.stdout.flush()
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sys.stderr.flush()
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self.returncode = None
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self.pid = os.fork()
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if self.pid == 0:
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if 'random' in sys.modules:
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import random
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random.seed()
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code = process_obj._bootstrap()
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sys.stdout.flush()
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sys.stderr.flush()
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os._exit(code)
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def poll(self, flag=os.WNOHANG):
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if self.returncode is None:
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pid, sts = os.waitpid(self.pid, flag)
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if pid == self.pid:
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if os.WIFSIGNALED(sts):
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self.returncode = -os.WTERMSIG(sts)
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else:
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assert os.WIFEXITED(sts)
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self.returncode = os.WEXITSTATUS(sts)
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return self.returncode
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def wait(self, timeout=None):
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if timeout is None:
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return self.poll(0)
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deadline = time.time() + timeout
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delay = 0.0005
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while 1:
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res = self.poll()
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if res is not None:
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break
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remaining = deadline - time.time()
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if remaining <= 0:
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break
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delay = min(delay * 2, remaining, 0.05)
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time.sleep(delay)
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return res
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def terminate(self):
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if self.returncode is None:
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try:
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os.kill(self.pid, signal.SIGTERM)
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except OSError, e:
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if self.wait(timeout=0.1) is None:
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raise
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@staticmethod
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def thread_is_spawning():
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return False
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#
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# Windows
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#
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else:
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import thread
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import msvcrt
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import _subprocess
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import copy_reg
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import time
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from ._multiprocessing import win32, Connection, PipeConnection
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from .util import Finalize
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try:
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from cPickle import dump, load, HIGHEST_PROTOCOL
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except ImportError:
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from pickle import dump, load, HIGHEST_PROTOCOL
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#
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#
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#
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TERMINATE = 0x10000
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WINEXE = (sys.platform == 'win32' and getattr(sys, 'frozen', False))
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exit = win32.ExitProcess
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close = win32.CloseHandle
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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.executable.lower().endswith('pythonservice.exe'):
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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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#
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#
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#
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def duplicate(handle, target_process=None, inheritable=False):
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if target_process is None:
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target_process = _subprocess.GetCurrentProcess()
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return _subprocess.DuplicateHandle(
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_subprocess.GetCurrentProcess(), handle, target_process,
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0, inheritable, _subprocess.DUPLICATE_SAME_ACCESS
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).Detach()
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#
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# We define a Popen class similar to the one from subprocess, but
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# whose constructor takes a process object as its argument.
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#
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class Popen(object):
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'''
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Start a subprocess to run the code of a process object
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'''
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_tls = thread._local()
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def __init__(self, process_obj):
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# create pipe for communication with child
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rfd, wfd = os.pipe()
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# get handle for read end of the pipe and make it inheritable
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rhandle = duplicate(msvcrt.get_osfhandle(rfd), inheritable=True)
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os.close(rfd)
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# start process
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cmd = get_command_line() + [rhandle]
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cmd = ' '.join('"%s"' % x for x in cmd)
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hp, ht, pid, tid = _subprocess.CreateProcess(
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_python_exe, cmd, None, None, 1, 0, None, None, None
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)
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ht.Close()
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close(rhandle)
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# set attributes of self
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self.pid = pid
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self.returncode = None
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self._handle = hp
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# send information to child
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prep_data = get_preparation_data(process_obj._name)
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to_child = os.fdopen(wfd, 'wb')
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Popen._tls.process_handle = int(hp)
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try:
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dump(prep_data, to_child, HIGHEST_PROTOCOL)
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dump(process_obj, to_child, HIGHEST_PROTOCOL)
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finally:
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del Popen._tls.process_handle
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to_child.close()
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@staticmethod
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def thread_is_spawning():
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return getattr(Popen._tls, 'process_handle', None) is not None
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@staticmethod
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def duplicate_for_child(handle):
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return duplicate(handle, Popen._tls.process_handle)
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def wait(self, timeout=None):
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if self.returncode is None:
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if timeout is None:
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msecs = _subprocess.INFINITE
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else:
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msecs = max(0, int(timeout * 1000 + 0.5))
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res = _subprocess.WaitForSingleObject(int(self._handle), msecs)
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if res == _subprocess.WAIT_OBJECT_0:
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code = _subprocess.GetExitCodeProcess(self._handle)
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if code == TERMINATE:
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code = -signal.SIGTERM
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self.returncode = code
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return self.returncode
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def poll(self):
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return self.wait(timeout=0)
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def terminate(self):
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if self.returncode is None:
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try:
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_subprocess.TerminateProcess(int(self._handle), TERMINATE)
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except WindowsError:
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if self.wait(timeout=0.1) is None:
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raise
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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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assert len(argv) == 3
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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():
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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 process.current_process()._identity==() and is_forking(sys.argv):
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raise RuntimeError('''
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Attempt to start a new process before the current process
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has finished its bootstrapping phase.
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This probably means that you are on Windows and you have
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forgotten to use the proper idiom 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 a Windows executable.''')
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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.forking import main; main()'
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return [_python_exe, '-c', prog, '--multiprocessing-fork']
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def main():
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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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handle = int(sys.argv[-1])
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fd = msvcrt.open_osfhandle(handle, os.O_RDONLY)
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from_parent = os.fdopen(fd, 'rb')
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process.current_process()._inheriting = True
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preparation_data = load(from_parent)
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prepare(preparation_data)
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self = load(from_parent)
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process.current_process()._inheriting = False
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from_parent.close()
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exitcode = self._bootstrap()
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exit(exitcode)
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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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from .util import _logger, _log_to_stderr
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d = dict(
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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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log_to_stderr=_log_to_stderr,
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orig_dir=process.ORIGINAL_DIR,
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authkey=process.current_process().get_authkey(),
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)
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if _logger is not None:
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d['log_level'] = _logger.getEffectiveLevel()
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if not WINEXE:
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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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# Make (Pipe)Connection picklable
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#
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def reduce_connection(conn):
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if not Popen.thread_is_spawning():
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raise RuntimeError(
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'By default %s objects can only be shared between processes\n'
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'using inheritance' % type(conn).__name__
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)
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return type(conn), (Popen.duplicate_for_child(conn.fileno()),
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conn.readable, conn.writable)
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copy_reg.pickle(Connection, reduce_connection)
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copy_reg.pickle(PipeConnection, reduce_connection)
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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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old_main_modules.append(sys.modules['__main__'])
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if 'name' in data:
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process.current_process().set_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 'main_path' in data:
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main_path = data['main_path']
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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 != 'ipython':
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import imp
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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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file, path_name, etc = imp.find_module(main_name, dirs)
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try:
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# We would like to do "imp.load_module('__main__', ...)"
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# here. However, that would cause 'if __name__ ==
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# "__main__"' clauses to be executed.
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main_module = imp.load_module(
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'__parents_main__', file, path_name, etc
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)
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finally:
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if file:
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file.close()
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sys.modules['__main__'] = main_module
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main_module.__name__ = '__main__'
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# Try to make the potentially picklable objects in
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# sys.modules['__main__'] realize they are in the main
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# module -- somewhat ugly.
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for obj in main_module.__dict__.values():
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try:
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if obj.__module__ == '__parents_main__':
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obj.__module__ = '__main__'
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except Exception:
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pass
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