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multiprocessing

Source code for multiprocessing

#
# Package analogous to 'threading.py' but using processes
#
# multiprocessing/__init__.py
#
# This package is intended to duplicate the functionality (and much of
# the API) of threading.py but uses processes instead of threads.  A
# subpackage 'multiprocessing.dummy' has the same API but is a simple
# wrapper for 'threading'.
#
# Try calling `multiprocessing.doc.main()` to read the html
# documentation in a webbrowser.
#
#
# Copyright (c) 2006-2008, R Oudkerk
# All rights reserved.
#
# Redistribution and use in source and binary forms, with or without
# modification, are permitted provided that the following conditions
# are met:
#
# 1. Redistributions of source code must retain the above copyright
#    notice, this list of conditions and the following disclaimer.
# 2. Redistributions in binary form must reproduce the above copyright
#    notice, this list of conditions and the following disclaimer in the
#    documentation and/or other materials provided with the distribution.
# 3. Neither the name of author nor the names of any contributors may be
#    used to endorse or promote products derived from this software
#    without specific prior written permission.
#
# THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS "AS IS" AND
# ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
# IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
# ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
# FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
# DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
# OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
# HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
# LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
# OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
# SUCH DAMAGE.
#

__version__ = '0.70a1'

__all__ = [
    'Process', 'current_process', 'active_children', 'freeze_support',
    'Manager', 'Pipe', 'cpu_count', 'log_to_stderr', 'get_logger',
    'allow_connection_pickling', 'BufferTooShort', 'TimeoutError',
    'Lock', 'RLock', 'Semaphore', 'BoundedSemaphore', 'Condition',
    'Event', 'Queue', 'JoinableQueue', 'Pool', 'Value', 'Array',
    'RawValue', 'RawArray', 'SUBDEBUG', 'SUBWARNING',
    ]

__author__ = 'R. Oudkerk (r.m.oudkerk@gmail.com)'

#
# Imports
#

import os
import sys

from multiprocessing.process import Process, current_process, active_children
from multiprocessing.util import SUBDEBUG, SUBWARNING

#
# Exceptions
#

class ProcessError(Exception):
    pass

[docs]class BufferTooShort(ProcessError): pass
class TimeoutError(ProcessError): pass
[docs]class AuthenticationError(ProcessError): pass
# This is down here because _multiprocessing uses BufferTooShort import _multiprocessing # # Definitions not depending on native semaphores # def Manager(): ''' Returns a manager associated with a running server process The managers methods such as `Lock()`, `Condition()` and `Queue()` can be used to create shared objects. ''' from multiprocessing.managers import SyncManager m = SyncManager() m.start() return m
[docs]def Pipe(duplex=True): ''' Returns two connection object connected by a pipe ''' from multiprocessing.connection import Pipe return Pipe(duplex)
[docs]def cpu_count(): ''' Returns the number of CPUs in the system ''' if sys.platform == 'win32': try: num = int(os.environ['NUMBER_OF_PROCESSORS']) except (ValueError, KeyError): num = 0 elif 'bsd' in sys.platform or sys.platform == 'darwin': comm = '/sbin/sysctl -n hw.ncpu' if sys.platform == 'darwin': comm = '/usr' + comm try: with os.popen(comm) as p: num = int(p.read()) except ValueError: num = 0 else: try: num = os.sysconf('SC_NPROCESSORS_ONLN') except (ValueError, OSError, AttributeError): num = 0 if num >= 1: return num else: raise NotImplementedError('cannot determine number of cpus')
[docs]def freeze_support(): ''' Check whether this is a fake forked process in a frozen executable. If so then run code specified by commandline and exit. ''' if sys.platform == 'win32' and getattr(sys, 'frozen', False): from multiprocessing.forking import freeze_support freeze_support()
[docs]def get_logger(): ''' Return package logger -- if it does not already exist then it is created ''' from multiprocessing.util import get_logger return get_logger()
[docs]def log_to_stderr(level=None): ''' Turn on logging and add a handler which prints to stderr ''' from multiprocessing.util import log_to_stderr return log_to_stderr(level)
def allow_connection_pickling(): ''' Install support for sending connections and sockets between processes ''' from multiprocessing import reduction # # Definitions depending on native semaphores #
[docs]def Lock(): ''' Returns a non-recursive lock object ''' from multiprocessing.synchronize import Lock return Lock()
[docs]def RLock(): ''' Returns a recursive lock object ''' from multiprocessing.synchronize import RLock return RLock()
[docs]def Condition(lock=None): ''' Returns a condition object ''' from multiprocessing.synchronize import Condition return Condition(lock)
[docs]def Semaphore(value=1): ''' Returns a semaphore object ''' from multiprocessing.synchronize import Semaphore return Semaphore(value)
[docs]def BoundedSemaphore(value=1): ''' Returns a bounded semaphore object ''' from multiprocessing.synchronize import BoundedSemaphore return BoundedSemaphore(value)
[docs]def Event(): ''' Returns an event object ''' from multiprocessing.synchronize import Event return Event()
[docs]def Queue(maxsize=0): ''' Returns a queue object ''' from multiprocessing.queues import Queue return Queue(maxsize)
[docs]def JoinableQueue(maxsize=0): ''' Returns a queue object ''' from multiprocessing.queues import JoinableQueue return JoinableQueue(maxsize)
def Pool(processes=None, initializer=None, initargs=(), maxtasksperchild=None): ''' Returns a process pool object ''' from multiprocessing.pool import Pool return Pool(processes, initializer, initargs, maxtasksperchild) def RawValue(typecode_or_type, *args): ''' Returns a shared object ''' from multiprocessing.sharedctypes import RawValue return RawValue(typecode_or_type, *args) def RawArray(typecode_or_type, size_or_initializer): ''' Returns a shared array ''' from multiprocessing.sharedctypes import RawArray return RawArray(typecode_or_type, size_or_initializer)
[docs]def Value(typecode_or_type, *args, **kwds): ''' Returns a synchronized shared object ''' from multiprocessing.sharedctypes import Value return Value(typecode_or_type, *args, **kwds)
[docs]def Array(typecode_or_type, size_or_initializer, **kwds): ''' Returns a synchronized shared array ''' from multiprocessing.sharedctypes import Array return Array(typecode_or_type, size_or_initializer, **kwds)
# # # if sys.platform == 'win32': def set_executable(executable): ''' Sets the path to a python.exe or pythonw.exe binary used to run child processes on Windows instead of sys.executable. Useful for people embedding Python. ''' from multiprocessing.forking import set_executable set_executable(executable) __all__ += ['set_executable']