cpython/Lib/multiprocessing/__init__.py

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#
# 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
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# documentation in a webbrowser.
#
#
# Copyright (c) 2006-2008, R Oudkerk
# Licensed to PSF under a Contributor Agreement.
#
__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', 'SimpleQueue', 'JoinableQueue', 'Pool', 'Value', 'Array',
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'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
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from multiprocessing.util import SUBDEBUG, SUBWARNING
#
# Exceptions
#
class ProcessError(Exception):
pass
class BufferTooShort(ProcessError):
pass
class TimeoutError(ProcessError):
pass
class AuthenticationError(ProcessError):
pass
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
def Pipe(duplex=True):
'''
Returns two connection object connected by a pipe
'''
from multiprocessing.connection import Pipe
return Pipe(duplex)
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
Merged revisions 67348,67355,67359,67362,67364-67365,67367-67368,67398,67423-67424,67432,67440-67441,67444-67445,67454-67455,67457-67458 via svnmerge from svn+ssh://pythondev@svn.python.org/python/trunk ........ r67348 | benjamin.peterson | 2008-11-22 20:09:41 -0600 (Sat, 22 Nov 2008) | 1 line raise a better error ........ r67355 | georg.brandl | 2008-11-23 13:17:25 -0600 (Sun, 23 Nov 2008) | 2 lines #4392: fix parameter name. ........ r67359 | georg.brandl | 2008-11-23 15:57:30 -0600 (Sun, 23 Nov 2008) | 2 lines #4399: fix typo. ........ r67362 | gregory.p.smith | 2008-11-23 18:41:43 -0600 (Sun, 23 Nov 2008) | 2 lines Document PY_SSIZE_T_CLEAN for PyArg_ParseTuple. ........ r67364 | benjamin.peterson | 2008-11-23 19:16:29 -0600 (Sun, 23 Nov 2008) | 2 lines replace reference to debugger-hooks ........ r67365 | benjamin.peterson | 2008-11-23 22:09:03 -0600 (Sun, 23 Nov 2008) | 1 line #4396 make the parser module correctly validate the with syntax ........ r67367 | georg.brandl | 2008-11-24 10:16:07 -0600 (Mon, 24 Nov 2008) | 2 lines Fix typo. ........ r67368 | georg.brandl | 2008-11-24 13:56:47 -0600 (Mon, 24 Nov 2008) | 2 lines #4404: make clear what "path" is. ........ r67398 | benjamin.peterson | 2008-11-26 11:39:17 -0600 (Wed, 26 Nov 2008) | 1 line fix typo in sqlite3 docs ........ r67423 | jesse.noller | 2008-11-28 12:59:35 -0600 (Fri, 28 Nov 2008) | 2 lines issue4238: bsd support for cpu_count ........ r67424 | christian.heimes | 2008-11-28 13:33:33 -0600 (Fri, 28 Nov 2008) | 1 line Retain copyright of processing examples. This was requested by a Debian maintainer during packaging of the multiprocessing package for 2.4/2.5 ........ r67432 | benjamin.peterson | 2008-11-28 17:18:46 -0600 (Fri, 28 Nov 2008) | 1 line SVN format 9 is the same it seems ........ r67440 | jeremy.hylton | 2008-11-28 17:42:59 -0600 (Fri, 28 Nov 2008) | 4 lines Move definition int sval into branch of ifdef where it is used. Otherwise, you get a warning about an undefined variable. ........ r67441 | jeremy.hylton | 2008-11-28 18:09:16 -0600 (Fri, 28 Nov 2008) | 2 lines Reflow long lines. ........ r67444 | amaury.forgeotdarc | 2008-11-28 20:03:32 -0600 (Fri, 28 Nov 2008) | 2 lines Fix a small typo in docstring ........ r67445 | benjamin.peterson | 2008-11-29 21:07:33 -0600 (Sat, 29 Nov 2008) | 1 line StringIO.close() stops you from using the buffer, too ........ r67454 | benjamin.peterson | 2008-11-30 08:43:23 -0600 (Sun, 30 Nov 2008) | 1 line note the version that works ........ r67455 | martin.v.loewis | 2008-11-30 13:28:27 -0600 (Sun, 30 Nov 2008) | 1 line Issue #4365: Add crtassem.h constants to the msvcrt module. ........ r67457 | christian.heimes | 2008-11-30 15:16:28 -0600 (Sun, 30 Nov 2008) | 1 line w# requires Py_ssize_t ........ r67458 | benjamin.peterson | 2008-11-30 15:46:16 -0600 (Sun, 30 Nov 2008) | 1 line fix pyspecific extensions that were broken by Sphinx's grand renaming ........
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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')
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()
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()
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
'''
# This is undocumented. In previous versions of multiprocessing
# its only effect was to make socket objects inheritable on Windows.
import multiprocessing.connection
#
# Definitions depending on native semaphores
#
def Lock():
'''
Returns a non-recursive lock object
'''
from multiprocessing.synchronize import Lock
return Lock()
def RLock():
'''
Returns a recursive lock object
'''
from multiprocessing.synchronize import RLock
return RLock()
def Condition(lock=None):
'''
Returns a condition object
'''
from multiprocessing.synchronize import Condition
return Condition(lock)
def Semaphore(value=1):
'''
Returns a semaphore object
'''
from multiprocessing.synchronize import Semaphore
return Semaphore(value)
def BoundedSemaphore(value=1):
'''
Returns a bounded semaphore object
'''
from multiprocessing.synchronize import BoundedSemaphore
return BoundedSemaphore(value)
def Event():
'''
Returns an event object
'''
from multiprocessing.synchronize import Event
return Event()
def Queue(maxsize=0):
'''
Returns a queue object
'''
from multiprocessing.queues import Queue
return Queue(maxsize)
def JoinableQueue(maxsize=0):
'''
Returns a queue object
'''
from multiprocessing.queues import JoinableQueue
return JoinableQueue(maxsize)
def SimpleQueue():
'''
Returns a queue object
'''
from multiprocessing.queues import SimpleQueue
return SimpleQueue()
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)
def Value(typecode_or_type, *args, **kwds):
'''
Returns a synchronized shared object
'''
from multiprocessing.sharedctypes import Value
return Value(typecode_or_type, *args, **kwds)
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']