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Issue #18999: Make multiprocessing use context objects.

Browse source 
This allows different parts of a program to use different methods for
starting processes without interfering with each other.
This commit is contained in:
Richard Oudkerk 2013-10-16 16:41:56 +01:00
parent 3e4b52875e
commit b1694cf588
20 changed files with 733 additions and 611 deletions
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76
Doc/library/multiprocessing.rst
View file

@ -98,8 +98,8 @@ necessary, see :ref:`multiprocessing-programming`.
Start methods
~~~~~~~~~~~~~
Contexts and start methods
~~~~~~~~~~~~~~~~~~~~~~~~~~
Depending on the platform, :mod:`multiprocessing` supports three ways
to start a process. These *start methods* are
@ -132,7 +132,7 @@ to start a process. These *start methods* are
unnecessary resources are inherited.
Available on Unix platforms which support passing file descriptors
over unix pipes.
over Unix pipes.
Before Python 3.4 *fork* was the only option available on Unix. Also,
prior to Python 3.4, child processes would inherit all the parents
@ -153,18 +153,46 @@ example::
import multiprocessing as mp
def foo():
print('hello')
def foo(q):
q.put('hello')
if __name__ == '__main__':
mp.set_start_method('spawn')
p = mp.Process(target=foo)
q = mp.Queue()
p = mp.Process(target=foo, args=(q,))
p.start()
print(q.get())
p.join()
:func:`set_start_method` should not be used more than once in the
program.
Alternatively, you can use :func:`get_context` to obtain a context
object. Context objects have the same API as the multiprocessing
module, and allow one to use multiple start methods in the same
program. ::
import multiprocessing as mp
def foo(q):
q.put('hello')
if __name__ == '__main__':
ctx = mp.get_context('spawn')
q = ctx.Queue()
p = ctx.Process(target=foo, args=(q,))
p.start()
print(q.get())
p.join()
Note that objects related to one context may not be compatible with
processes for a different context. In particular, locks created using
the *fork* context cannot be passed to a processes started using the
*spawn* or *forkserver* start methods.
A library which wants to use a particular start method should probably
use :func:`get_context` to avoid interfering with the choice of the
library user.
Exchanging objects between processes
@ -859,11 +887,30 @@ Miscellaneous
.. versionadded:: 3.4
.. function:: get_start_method()
.. function:: get_context(method=None)
Return the current start method. This can be ``'fork'``,
``'spawn'`` or ``'forkserver'``. ``'fork'`` is the default on
Unix, while ``'spawn'`` is the default on Windows.
Return a context object which has the same attributes as the
:mod:`multiprocessing` module.
If *method* is *None* then the default context is returned.
Otherwise *method* should be ``'fork'``, ``'spawn'``,
``'forkserver'``. :exc:`ValueError` is raised if the specified
start method is not available.
.. versionadded:: 3.4
.. function:: get_start_method(allow_none=False)
Return the name of start method used for starting processes.
If the start method has not been fixed and *allow_none* is false,
then the start method is fixed to the default and the name is
returned. If the start method has not been fixed and *allow_none*
is true then *None* is returned.
The return value can be ``'fork'``, ``'spawn'``, ``'forkserver'``
or *None*. ``'fork'`` is the default on Unix, while ``'spawn'`` is
the default on Windows.
.. versionadded:: 3.4
@ -1785,7 +1832,7 @@ Process Pools
One can create a pool of processes which will carry out tasks submitted to it
with the :class:`Pool` class.
.. class:: Pool([processes[, initializer[, initargs[, maxtasksperchild]]]])
.. class:: Pool([processes[, initializer[, initargs[, maxtasksperchild [, context]]]]])
A process pool object which controls a pool of worker processes to which jobs
can be submitted. It supports asynchronous results with timeouts and
@ -1805,6 +1852,13 @@ with the :class:`Pool` class.
unused resources to be freed. The default *maxtasksperchild* is None, which
means worker processes will live as long as the pool.
.. versionadded:: 3.4
*context* can be used to specify the context used for starting
the worker processes. Usually a pool is created using the
function :func:`multiprocessing.Pool` or the :meth:`Pool` method
of a context object. In both cases *context* is set
appropriately.
.. note::
Worker processes within a :class:`Pool` typically live for the complete

264
Lib/multiprocessing/__init__.py
View file

@ -12,27 +12,16 @@
# 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', 'Barrier', 'Queue', 'SimpleQueue', 'JoinableQueue', 'Pool',
'Value', 'Array', 'RawValue', 'RawArray', 'SUBDEBUG', 'SUBWARNING',
'set_executable', 'set_start_method', 'get_start_method',
'get_all_start_methods', 'set_forkserver_preload'
]
#
# Imports
#
import os
import sys
from . import context
from .process import Process, current_process, active_children
#
# Copy stuff from default context
#
globals().update((name, getattr(context._default_context, name))
for name in context._default_context.__all__)
__all__ = context._default_context.__all__
#
# XXX These should not really be documented or public.
@ -47,240 +36,3 @@
if '__main__' in sys.modules:
sys.modules['__mp_main__'] = sys.modules['__main__']
#
# Exceptions
#
class ProcessError(Exception):
pass
class BufferTooShort(ProcessError):
pass
class TimeoutError(ProcessError):
pass
class AuthenticationError(ProcessError):
pass
#
# 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 .managers import SyncManager
m = SyncManager()
m.start()
return m
def Pipe(duplex=True):
'''
Returns two connection object connected by a pipe
'''
from .connection import Pipe
return Pipe(duplex)
def cpu_count():
'''
Returns the number of CPUs in the system
'''
num = os.cpu_count()
if num is None:
raise NotImplementedError('cannot determine number of cpus')
else:
return num
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 .spawn import freeze_support
freeze_support()
def get_logger():
'''
Return package logger -- if it does not already exist then it is created
'''
from .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 .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.
from . import connection
#
# Definitions depending on native semaphores
#
def Lock():
'''
Returns a non-recursive lock object
'''
from .synchronize import Lock
return Lock()
def RLock():
'''
Returns a recursive lock object
'''
from .synchronize import RLock
return RLock()
def Condition(lock=None):
'''
Returns a condition object
'''
from .synchronize import Condition
return Condition(lock)
def Semaphore(value=1):
'''
Returns a semaphore object
'''
from .synchronize import Semaphore
return Semaphore(value)
def BoundedSemaphore(value=1):
'''
Returns a bounded semaphore object
'''
from .synchronize import BoundedSemaphore
return BoundedSemaphore(value)
def Event():
'''
Returns an event object
'''
from .synchronize import Event
return Event()
def Barrier(parties, action=None, timeout=None):
'''
Returns a barrier object
'''
from .synchronize import Barrier
return Barrier(parties, action, timeout)
def Queue(maxsize=0):
'''
Returns a queue object
'''
from .queues import Queue
return Queue(maxsize)
def JoinableQueue(maxsize=0):
'''
Returns a queue object
'''
from .queues import JoinableQueue
return JoinableQueue(maxsize)
def SimpleQueue():
'''
Returns a queue object
'''
from .queues import SimpleQueue
return SimpleQueue()
def Pool(processes=None, initializer=None, initargs=(), maxtasksperchild=None):
'''
Returns a process pool object
'''
from .pool import Pool
return Pool(processes, initializer, initargs, maxtasksperchild)
def RawValue(typecode_or_type, *args):
'''
Returns a shared object
'''
from .sharedctypes import RawValue
return RawValue(typecode_or_type, *args)
def RawArray(typecode_or_type, size_or_initializer):
'''
Returns a shared array
'''
from .sharedctypes import RawArray
return RawArray(typecode_or_type, size_or_initializer)
def Value(typecode_or_type, *args, lock=True):
'''
Returns a synchronized shared object
'''
from .sharedctypes import Value
return Value(typecode_or_type, *args, lock=lock)
def Array(typecode_or_type, size_or_initializer, *, lock=True):
'''
Returns a synchronized shared array
'''
from .sharedctypes import Array
return Array(typecode_or_type, size_or_initializer, lock=lock)
#
#
#
def set_executable(executable):
'''
Sets the path to a python.exe or pythonw.exe binary used to run
child processes instead of sys.executable when using the 'spawn'
start method. Useful for people embedding Python.
'''
from .spawn import set_executable
set_executable(executable)
def set_start_method(method):
'''
Set method for starting processes: 'fork', 'spawn' or 'forkserver'.
'''
from .popen import set_start_method
set_start_method(method)
def get_start_method():
'''
Get method for starting processes: 'fork', 'spawn' or 'forkserver'.
'''
from .popen import get_start_method
return get_start_method()
def get_all_start_methods():
'''
Get list of availables start methods, default first.
'''
from .popen import get_all_start_methods
return get_all_start_methods()
def set_forkserver_preload(module_names):
'''
Set list of module names to try to load in the forkserver process
when it is started. Properly chosen this can significantly reduce
the cost of starting a new process using the forkserver method.
The default list is ['__main__'].
'''
try:
from .forkserver import set_forkserver_preload
except ImportError:
pass
else:
set_forkserver_preload(module_names)

348
Lib/multiprocessing/context.py Normal file
View file

@ -0,0 +1,348 @@
import os
import sys
import threading
from . import process
__all__ = [] # things are copied from here to __init__.py
#
# Exceptions
#
class ProcessError(Exception):
pass
class BufferTooShort(ProcessError):
pass
class TimeoutError(ProcessError):
pass
class AuthenticationError(ProcessError):
pass
#
# Base type for contexts
#
class BaseContext(object):
ProcessError = ProcessError
BufferTooShort = BufferTooShort
TimeoutError = TimeoutError
AuthenticationError = AuthenticationError
current_process = staticmethod(process.current_process)
active_children = staticmethod(process.active_children)
def cpu_count(self):
'''Returns the number of CPUs in the system'''
num = os.cpu_count()
if num is None:
raise NotImplementedError('cannot determine number of cpus')
else:
return num
def Manager(self):
'''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 .managers import SyncManager
m = SyncManager(ctx=self.get_context())
m.start()
return m
def Pipe(self, duplex=True):
'''Returns two connection object connected by a pipe'''
from .connection import Pipe
return Pipe(duplex)
def Lock(self):
'''Returns a non-recursive lock object'''
from .synchronize import Lock
return Lock(ctx=self.get_context())
def RLock(self):
'''Returns a recursive lock object'''
from .synchronize import RLock
return RLock(ctx=self.get_context())
def Condition(self, lock=None):
'''Returns a condition object'''
from .synchronize import Condition
return Condition(lock, ctx=self.get_context())
def Semaphore(self, value=1):
'''Returns a semaphore object'''
from .synchronize import Semaphore
return Semaphore(value, ctx=self.get_context())
def BoundedSemaphore(self, value=1):
'''Returns a bounded semaphore object'''
from .synchronize import BoundedSemaphore
return BoundedSemaphore(value, ctx=self.get_context())
def Event(self):
'''Returns an event object'''
from .synchronize import Event
return Event(ctx=self.get_context())
def Barrier(self, parties, action=None, timeout=None):
'''Returns a barrier object'''
from .synchronize import Barrier
return Barrier(parties, action, timeout, ctx=self.get_context())
def Queue(self, maxsize=0):
'''Returns a queue object'''
from .queues import Queue
return Queue(maxsize, ctx=self.get_context())
def JoinableQueue(self, maxsize=0):
'''Returns a queue object'''
from .queues import JoinableQueue
return JoinableQueue(maxsize, ctx=self.get_context())
def SimpleQueue(self):
'''Returns a queue object'''
from .queues import SimpleQueue
return SimpleQueue(ctx=self.get_context())
def Pool(self, processes=None, initializer=None, initargs=(),
maxtasksperchild=None):
'''Returns a process pool object'''
from .pool import Pool
return Pool(processes, initializer, initargs, maxtasksperchild,
context=self.get_context())
def RawValue(self, typecode_or_type, *args):
'''Returns a shared object'''
from .sharedctypes import RawValue
return RawValue(typecode_or_type, *args)
def RawArray(self, typecode_or_type, size_or_initializer):
'''Returns a shared array'''
from .sharedctypes import RawArray
return RawArray(typecode_or_type, size_or_initializer)
def Value(self, typecode_or_type, *args, lock=True):
'''Returns a synchronized shared object'''
from .sharedctypes import Value
return Value(typecode_or_type, *args, lock=lock,
ctx=self.get_context())
def Array(self, typecode_or_type, size_or_initializer, *, lock=True):
'''Returns a synchronized shared array'''
from .sharedctypes import Array
return Array(typecode_or_type, size_or_initializer, lock=lock,
ctx=self.get_context())
def freeze_support(self):
'''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 .spawn import freeze_support
freeze_support()
def get_logger(self):
'''Return package logger -- if it does not already exist then
it is created.
'''
from .util import get_logger
return get_logger()
def log_to_stderr(self, level=None):
'''Turn on logging and add a handler which prints to stderr'''
from .util import log_to_stderr
return log_to_stderr(level)
def allow_connection_pickling(self):
'''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.
from . import connection
def set_executable(self, executable):
'''Sets the path to a python.exe or pythonw.exe binary used to run
child processes instead of sys.executable when using the 'spawn'
start method. Useful for people embedding Python.
'''
from .spawn import set_executable
set_executable(executable)
def set_forkserver_preload(self, module_names):
'''Set list of module names to try to load in forkserver process.
This is really just a hint.
'''
from .forkserver import set_forkserver_preload
set_forkserver_preload(module_names)
def get_context(self, method=None):
if method is None:
return self
try:
ctx = _concrete_contexts[method]
except KeyError:
raise ValueError('cannot find context for %r' % method)
ctx._check_available()
return ctx
def get_start_method(self, allow_none=False):
return self._name
def set_start_method(self, method=None):
raise ValueError('cannot set start method of concrete context')
def _check_available(self):
pass
#
# Type of default context -- underlying context can be set at most once
#
class Process(process.BaseProcess):
_start_method = None
@staticmethod
def _Popen(process_obj):
return _default_context.get_context().Process._Popen(process_obj)
class DefaultContext(BaseContext):
Process = Process
def __init__(self, context):
self._default_context = context
self._actual_context = None
def get_context(self, method=None):
if method is None:
if self._actual_context is None:
self._actual_context = self._default_context
return self._actual_context
else:
return super().get_context(method)
def set_start_method(self, method, force=False):
if self._actual_context is not None and not force:
raise RuntimeError('context has already been set')
if method is None and force:
self._actual_context = None
return
self._actual_context = self.get_context(method)
def get_start_method(self, allow_none=False):
if self._actual_context is None:
if allow_none:
return None
self._actual_context = self._default_context
return self._actual_context._name
def get_all_start_methods(self):
if sys.platform == 'win32':
return ['spawn']
else:
from . import reduction
if reduction.HAVE_SEND_HANDLE:
return ['fork', 'spawn', 'forkserver']
else:
return ['fork', 'spawn']
DefaultContext.__all__ = list(x for x in dir(DefaultContext) if x[0] != '_')
#
# Context types for fixed start method
#
if sys.platform != 'win32':
class ForkProcess(process.BaseProcess):
_start_method = 'fork'
@staticmethod
def _Popen(process_obj):
from .popen_fork import Popen
return Popen(process_obj)
class SpawnProcess(process.BaseProcess):
_start_method = 'spawn'
@staticmethod
def _Popen(process_obj):
from .popen_spawn_posix import Popen
return Popen(process_obj)
class ForkServerProcess(process.BaseProcess):
_start_method = 'forkserver'
@staticmethod
def _Popen(process_obj):
from .popen_forkserver import Popen
return Popen(process_obj)
class ForkContext(BaseContext):
_name = 'fork'
Process = ForkProcess
class SpawnContext(BaseContext):
_name = 'spawn'
Process = SpawnProcess
class ForkServerContext(BaseContext):
_name = 'forkserver'
Process = ForkServerProcess
def _check_available(self):
from . import reduction
if not reduction.HAVE_SEND_HANDLE:
raise ValueError('forkserver start method not available')
_concrete_contexts = {
'fork': ForkContext(),
'spawn': SpawnContext(),
'forkserver': ForkServerContext(),
}
_default_context = DefaultContext(_concrete_contexts['fork'])
else:
class SpawnProcess(process.BaseProcess):
_start_method = 'spawn'
@staticmethod
def _Popen(process_obj):
from .popen_spawn_win32 import Popen
return Popen(process_obj)
class SpawnContext(BaseContext):
_name = 'spawn'
Process = SpawnProcess
_concrete_contexts = {
'spawn': SpawnContext(),
}
_default_context = DefaultContext(_concrete_contexts['spawn'])
#
# Force the start method
#
def _force_start_method(method):
_default_context._actual_context = _concrete_contexts[method]
#
# Check that the current thread is spawning a child process
#
_tls = threading.local()
def get_spawning_popen():
return getattr(_tls, 'spawning_popen', None)
def set_spawning_popen(popen):
_tls.spawning_popen = popen
def assert_spawning(obj):
if get_spawning_popen() is None:
raise RuntimeError(
'%s objects should only be shared between processes'
' through inheritance' % type(obj).__name__
)

202
Lib/multiprocessing/forkserver.py
View file

@ -24,105 +24,113 @@
MAXFDS_TO_SEND = 256
UNSIGNED_STRUCT = struct.Struct('Q') # large enough for pid_t
_forkserver_address = None
_forkserver_alive_fd = None
_inherited_fds = None
_lock = threading.Lock()
_preload_modules = ['__main__']
#
# Public function
# Forkserver class
#
def set_forkserver_preload(modules_names):
'''Set list of module names to try to load in forkserver process.'''
global _preload_modules
_preload_modules = modules_names
class ForkServer(object):
def __init__(self):
self._forkserver_address = None
self._forkserver_alive_fd = None
self._inherited_fds = None
self._lock = threading.Lock()
self._preload_modules = ['__main__']
def get_inherited_fds():
'''Return list of fds inherited from parent process.
def set_forkserver_preload(self, modules_names):
'''Set list of module names to try to load in forkserver process.'''
if not all(type(mod) is str for mod in self._preload_modules):
raise TypeError('module_names must be a list of strings')
self._preload_modules = modules_names
This returns None if the current process was not started by fork server.
'''
return _inherited_fds
def get_inherited_fds(self):
'''Return list of fds inherited from parent process.
This returns None if the current process was not started by fork
server.
'''
return self._inherited_fds
def connect_to_new_process(fds):
'''Request forkserver to create a child process.
def connect_to_new_process(self, fds):
'''Request forkserver to create a child process.
Returns a pair of fds (status_r, data_w). The calling process can read
the child process's pid and (eventually) its returncode from status_r.
The calling process should write to data_w the pickled preparation and
process data.
'''
if len(fds) + 4 >= MAXFDS_TO_SEND:
raise ValueError('too many fds')
with socket.socket(socket.AF_UNIX) as client:
client.connect(_forkserver_address)
parent_r, child_w = os.pipe()
child_r, parent_w = os.pipe()
allfds = [child_r, child_w, _forkserver_alive_fd,
semaphore_tracker._semaphore_tracker_fd]
allfds += fds
try:
reduction.sendfds(client, allfds)
return parent_r, parent_w
except:
os.close(parent_r)
os.close(parent_w)
raise
finally:
os.close(child_r)
os.close(child_w)
def ensure_running():
'''Make sure that a fork server is running.
This can be called from any process. Note that usually a child
process will just reuse the forkserver started by its parent, so
ensure_running() will do nothing.
'''
global _forkserver_address, _forkserver_alive_fd
with _lock:
if _forkserver_alive_fd is not None:
return
assert all(type(mod) is str for mod in _preload_modules)
cmd = ('from multiprocessing.forkserver import main; ' +
'main(%d, %d, %r, **%r)')
if _preload_modules:
desired_keys = {'main_path', 'sys_path'}
data = spawn.get_preparation_data('ignore')
data = dict((x,y) for (x,y) in data.items() if x in desired_keys)
else:
data = {}
with socket.socket(socket.AF_UNIX) as listener:
address = connection.arbitrary_address('AF_UNIX')
listener.bind(address)
os.chmod(address, 0o600)
listener.listen(100)
# all client processes own the write end of the "alive" pipe;
# when they all terminate the read end becomes ready.
alive_r, alive_w = os.pipe()
Returns a pair of fds (status_r, data_w). The calling process can read
the child process's pid and (eventually) its returncode from status_r.
The calling process should write to data_w the pickled preparation and
process data.
'''
self.ensure_running()
if len(fds) + 4 >= MAXFDS_TO_SEND:
raise ValueError('too many fds')
with socket.socket(socket.AF_UNIX) as client:
client.connect(self._forkserver_address)
parent_r, child_w = os.pipe()
child_r, parent_w = os.pipe()
allfds = [child_r, child_w, self._forkserver_alive_fd,
semaphore_tracker.getfd()]
allfds += fds
try:
fds_to_pass = [listener.fileno(), alive_r]
cmd %= (listener.fileno(), alive_r, _preload_modules, data)
exe = spawn.get_executable()
args = [exe] + util._args_from_interpreter_flags() + ['-c', cmd]
pid = util.spawnv_passfds(exe, args, fds_to_pass)
reduction.sendfds(client, allfds)
return parent_r, parent_w
except:
os.close(alive_w)
os.close(parent_r)
os.close(parent_w)
raise
finally:
os.close(alive_r)
_forkserver_address = address
_forkserver_alive_fd = alive_w
os.close(child_r)
os.close(child_w)
def ensure_running(self):
'''Make sure that a fork server is running.
This can be called from any process. Note that usually a child
process will just reuse the forkserver started by its parent, so
ensure_running() will do nothing.
'''
with self._lock:
semaphore_tracker.ensure_running()
if self._forkserver_alive_fd is not None:
return
cmd = ('from multiprocessing.forkserver import main; ' +
'main(%d, %d, %r, **%r)')
if self._preload_modules:
desired_keys = {'main_path', 'sys_path'}
data = spawn.get_preparation_data('ignore')
data = dict((x,y) for (x,y) in data.items()
if x in desired_keys)
else:
data = {}
with socket.socket(socket.AF_UNIX) as listener:
address = connection.arbitrary_address('AF_UNIX')
listener.bind(address)
os.chmod(address, 0o600)
listener.listen(100)
# all client processes own the write end of the "alive" pipe;
# when they all terminate the read end becomes ready.
alive_r, alive_w = os.pipe()
try:
fds_to_pass = [listener.fileno(), alive_r]
cmd %= (listener.fileno(), alive_r, self._preload_modules,
data)
exe = spawn.get_executable()
args = [exe] + util._args_from_interpreter_flags()
args += ['-c', cmd]
pid = util.spawnv_passfds(exe, args, fds_to_pass)
except:
os.close(alive_w)
raise
finally:
os.close(alive_r)
self._forkserver_address = address
self._forkserver_alive_fd = alive_w
#
#
#
def main(listener_fd, alive_r, preload, main_path=None, sys_path=None):
'''Run forkserver.'''
@ -151,8 +159,7 @@ def main(listener_fd, alive_r, preload, main_path=None, sys_path=None):
handler = signal.signal(signal.SIGCHLD, signal.SIG_IGN)
with socket.socket(socket.AF_UNIX, fileno=listener_fd) as listener, \
selectors.DefaultSelector() as selector:
global _forkserver_address
_forkserver_address = listener.getsockname()
_forkserver._forkserver_address = listener.getsockname()
selector.register(listener, selectors.EVENT_READ)
selector.register(alive_r, selectors.EVENT_READ)
@ -187,13 +194,7 @@ def main(listener_fd, alive_r, preload, main_path=None, sys_path=None):
if e.errno != errno.ECONNABORTED:
raise
#
# Code to bootstrap new process
#
def _serve_one(s, listener, alive_r, handler):
global _inherited_fds, _forkserver_alive_fd
# close unnecessary stuff and reset SIGCHLD handler
listener.close()
os.close(alive_r)
@ -203,8 +204,9 @@ def _serve_one(s, listener, alive_r, handler):
fds = reduction.recvfds(s, MAXFDS_TO_SEND + 1)
s.close()
assert len(fds) <= MAXFDS_TO_SEND
child_r, child_w, _forkserver_alive_fd, stfd, *_inherited_fds = fds
semaphore_tracker._semaphore_tracker_fd = stfd
(child_r, child_w, _forkserver._forkserver_alive_fd,
stfd, *_forkserver._inherited_fds) = fds
semaphore_tracker._semaphore_tracker._fd = stfd
# send pid to client processes
write_unsigned(child_w, os.getpid())
@ -253,3 +255,13 @@ def write_unsigned(fd, n):
if nbytes == 0:
raise RuntimeError('should not get here')
msg = msg[nbytes:]
#
#
#
_forkserver = ForkServer()
ensure_running = _forkserver.ensure_running
get_inherited_fds = _forkserver.get_inherited_fds
connect_to_new_process = _forkserver.connect_to_new_process
set_forkserver_preload = _forkserver.set_forkserver_preload

4
Lib/multiprocessing/heap.py
View file

@ -16,7 +16,7 @@
import threading
import _multiprocessing
from . import popen
from . import context
from . import reduction
from . import util
@ -50,7 +50,7 @@ def __init__(self, size):
self._state = (self.size, self.name)
def __getstate__(self):
popen.assert_spawning(self)
context.assert_spawning(self)
return self._state
def __setstate__(self, state):

11
Lib/multiprocessing/managers.py
View file

@ -23,11 +23,12 @@
from traceback import format_exc
from . import connection
from . import context
from . import pool
from . import process
from . import popen
from . import reduction
from . import util
from . import get_context
#
# Register some things for pickling
@ -438,7 +439,8 @@ class BaseManager(object):
_registry = {}
_Server = Server
def __init__(self, address=None, authkey=None, serializer='pickle'):
def __init__(self, address=None, authkey=None, serializer='pickle',
ctx=None):
if authkey is None:
authkey = process.current_process().authkey
self._address = address # XXX not final address if eg ('', 0)
@ -447,6 +449,7 @@ def __init__(self, address=None, authkey=None, serializer='pickle'):
self._state.value = State.INITIAL
self._serializer = serializer
self._Listener, self._Client = listener_client[serializer]
self._ctx = ctx or get_context()
def get_server(self):
'''
@ -478,7 +481,7 @@ def start(self, initializer=None, initargs=()):
reader, writer = connection.Pipe(duplex=False)
# spawn process which runs a server
self._process = process.Process(
self._process = self._ctx.Process(
target=type(self)._run_server,
args=(self._registry, self._address, self._authkey,
self._serializer, writer, initializer, initargs),
@ -800,7 +803,7 @@ def _after_fork(self):
def __reduce__(self):
kwds = {}
if popen.get_spawning_popen() is not None:
if context.get_spawning_popen() is not None:
kwds['authkey'] = self._authkey
if getattr(self, '_isauto', False):

12
Lib/multiprocessing/pool.py
View file

@ -24,7 +24,7 @@
# If threading is available then ThreadPool should be provided. Therefore
# we avoid top-level imports which are liable to fail on some systems.
from . import util
from . import Process, cpu_count, TimeoutError, SimpleQueue
from . import get_context, cpu_count, TimeoutError
#
# Constants representing the state of a pool
@ -137,10 +137,12 @@ class Pool(object):
'''
Class which supports an async version of applying functions to arguments.
'''
Process = Process
def Process(self, *args, **kwds):
return self._ctx.Process(*args, **kwds)
def __init__(self, processes=None, initializer=None, initargs=(),
maxtasksperchild=None):
maxtasksperchild=None, context=None):
self._ctx = context or get_context()
self._setup_queues()
self._taskqueue = queue.Queue()
self._cache = {}
@ -232,8 +234,8 @@ def _maintain_pool(self):
self._repopulate_pool()
def _setup_queues(self):
self._inqueue = SimpleQueue()
self._outqueue = SimpleQueue()
self._inqueue = self._ctx.SimpleQueue()
self._outqueue = self._ctx.SimpleQueue()
self._quick_put = self._inqueue._writer.send
self._quick_get = self._outqueue._reader.recv

78
Lib/multiprocessing/popen.py
View file

@ -1,78 +0,0 @@
import sys
import threading
__all__ = ['Popen', 'get_spawning_popen', 'set_spawning_popen',
'assert_spawning']
#
# Check that the current thread is spawning a child process
#
_tls = threading.local()
def get_spawning_popen():
return getattr(_tls, 'spawning_popen', None)
def set_spawning_popen(popen):
_tls.spawning_popen = popen
def assert_spawning(obj):
if get_spawning_popen() is None:
raise RuntimeError(
'%s objects should only be shared between processes'
' through inheritance' % type(obj).__name__
)
#
#
#
_Popen = None
def Popen(process_obj):
if _Popen is None:
set_start_method()
return _Popen(process_obj)
def get_start_method():
if _Popen is None:
set_start_method()
return _Popen.method
def set_start_method(meth=None, *, start_helpers=True):
global _Popen
try:
modname = _method_to_module[meth]
__import__(modname)
except (KeyError, ImportError):
raise ValueError('could not use start method %r' % meth)
module = sys.modules[modname]
if start_helpers:
module.Popen.ensure_helpers_running()
_Popen = module.Popen
if sys.platform == 'win32':
_method_to_module = {
None: 'multiprocessing.popen_spawn_win32',
'spawn': 'multiprocessing.popen_spawn_win32',
}
def get_all_start_methods():
return ['spawn']
else:
_method_to_module = {
None: 'multiprocessing.popen_fork',
'fork': 'multiprocessing.popen_fork',
'spawn': 'multiprocessing.popen_spawn_posix',
'forkserver': 'multiprocessing.popen_forkserver',
}
def get_all_start_methods():
from . import reduction
if reduction.HAVE_SEND_HANDLE:
return ['fork', 'spawn', 'forkserver']
else:
return ['fork', 'spawn']

4
Lib/multiprocessing/popen_fork.py
View file

@ -81,7 +81,3 @@ def _launch(self, process_obj):
os.close(child_w)
util.Finalize(self, os.close, (parent_r,))
self.sentinel = parent_r
@staticmethod
def ensure_helpers_running():
pass

12
Lib/multiprocessing/popen_forkserver.py
View file

@ -4,8 +4,8 @@
from . import reduction
if not reduction.HAVE_SEND_HANDLE:
raise ImportError('No support for sending fds between processes')
from . import context
from . import forkserver
from . import popen
from . import popen_fork
from . import spawn
from . import util
@ -42,12 +42,12 @@ def duplicate_for_child(self, fd):
def _launch(self, process_obj):
prep_data = spawn.get_preparation_data(process_obj._name)
buf = io.BytesIO()
popen.set_spawning_popen(self)
context.set_spawning_popen(self)
try:
reduction.dump(prep_data, buf)
reduction.dump(process_obj, buf)
finally:
popen.set_spawning_popen(None)
context.set_spawning_popen(None)
self.sentinel, w = forkserver.connect_to_new_process(self._fds)
util.Finalize(self, os.close, (self.sentinel,))
@ -67,9 +67,3 @@ def poll(self, flag=os.WNOHANG):
# The process ended abnormally perhaps because of a signal
self.returncode = 255
return self.returncode
@staticmethod
def ensure_helpers_running():
from . import semaphore_tracker
semaphore_tracker.ensure_running()
forkserver.ensure_running()

13
Lib/multiprocessing/popen_spawn_posix.py
View file

@ -2,7 +2,7 @@
import io
import os
from . import popen
from . import context
from . import popen_fork
from . import reduction
from . import spawn
@ -41,16 +41,16 @@ def duplicate_for_child(self, fd):
def _launch(self, process_obj):
from . import semaphore_tracker
tracker_fd = semaphore_tracker._semaphore_tracker_fd
tracker_fd = semaphore_tracker.getfd()
self._fds.append(tracker_fd)
prep_data = spawn.get_preparation_data(process_obj._name)
fp = io.BytesIO()
popen.set_spawning_popen(self)
context.set_spawning_popen(self)
try:
reduction.dump(prep_data, fp)
reduction.dump(process_obj, fp)
finally:
popen.set_spawning_popen(None)
context.set_spawning_popen(None)
parent_r = child_w = child_r = parent_w = None
try:
@ -70,8 +70,3 @@ def _launch(self, process_obj):
for fd in (child_r, child_w, parent_w):
if fd is not None:
os.close(fd)
@staticmethod
def ensure_helpers_running():
from . import semaphore_tracker
semaphore_tracker.ensure_running()

12
Lib/multiprocessing/popen_spawn_win32.py
View file

@ -4,8 +4,8 @@
import sys
import _winapi
from . import context
from . import spawn
from . import popen
from . import reduction
from . import util
@ -60,15 +60,15 @@ def __init__(self, process_obj):
util.Finalize(self, _winapi.CloseHandle, (self.sentinel,))
# send information to child
popen.set_spawning_popen(self)
context.set_spawning_popen(self)
try:
reduction.dump(prep_data, to_child)
reduction.dump(process_obj, to_child)
finally:
popen.set_spawning_popen(None)
context.set_spawning_popen(None)
def duplicate_for_child(self, handle):
assert self is popen.get_spawning_popen()
assert self is context.get_spawning_popen()
return reduction.duplicate(handle, self.sentinel)
def wait(self, timeout=None):
@ -97,7 +97,3 @@ def terminate(self):
except OSError:
if self.wait(timeout=1.0) is None:
raise
@staticmethod
def ensure_helpers_running():
pass

21
Lib/multiprocessing/process.py
View file

@ -7,7 +7,7 @@
# Licensed to PSF under a Contributor Agreement.
#
__all__ = ['Process', 'current_process', 'active_children']
__all__ = ['BaseProcess', 'current_process', 'active_children']
#
# Imports
@ -59,13 +59,14 @@ def _cleanup():
# The `Process` class
#
class Process(object):
class BaseProcess(object):
'''
Process objects represent activity that is run in a separate process
The class is analogous to `threading.Thread`
'''
_Popen = None
def _Popen(self):
raise NotImplementedError
def __init__(self, group=None, target=None, name=None, args=(), kwargs={},
*, daemon=None):
@ -101,11 +102,7 @@ def start(self):
assert not _current_process._config.get('daemon'), \
'daemonic processes are not allowed to have children'
_cleanup()
if self._Popen is not None:
Popen = self._Popen
else:
from .popen import Popen
self._popen = Popen(self)
self._popen = self._Popen(self)
self._sentinel = self._popen.sentinel
_children.add(self)
@ -229,10 +226,12 @@ def __repr__(self):
##
def _bootstrap(self):
from . import util
from . import util, context
global _current_process, _process_counter, _children
try:
if self._start_method is not None:
context._force_start_method(self._start_method)
_process_counter = itertools.count(1)
_children = set()
if sys.stdin is not None:
@ -282,7 +281,7 @@ def _bootstrap(self):
class AuthenticationString(bytes):
def __reduce__(self):
from .popen import get_spawning_popen
from .context import get_spawning_popen
if get_spawning_popen() is None:
raise TypeError(
'Pickling an AuthenticationString object is '
@ -294,7 +293,7 @@ def __reduce__(self):
# Create object representing the main process
#
class _MainProcess(Process):
class _MainProcess(BaseProcess):
def __init__(self):
self._identity = ()

29
Lib/multiprocessing/queues.py
View file

@ -22,8 +22,7 @@
import _multiprocessing
from . import connection
from . import popen
from . import synchronize
from . import context
from .util import debug, info, Finalize, register_after_fork, is_exiting
from .reduction import ForkingPickler
@ -34,18 +33,18 @@
class Queue(object):
def __init__(self, maxsize=0):
def __init__(self, maxsize=0, *, ctx):
if maxsize <= 0:
maxsize = _multiprocessing.SemLock.SEM_VALUE_MAX
self._maxsize = maxsize
self._reader, self._writer = connection.Pipe(duplex=False)
self._rlock = synchronize.Lock()
self._rlock = ctx.Lock()
self._opid = os.getpid()
if sys.platform == 'win32':
self._wlock = None
else:
self._wlock = synchronize.Lock()
self._sem = synchronize.BoundedSemaphore(maxsize)
self._wlock = ctx.Lock()
self._sem = ctx.BoundedSemaphore(maxsize)
# For use by concurrent.futures
self._ignore_epipe = False
@ -55,7 +54,7 @@ def __init__(self, maxsize=0):
register_after_fork(self, Queue._after_fork)
def __getstate__(self):
popen.assert_spawning(self)
context.assert_spawning(self)
return (self._ignore_epipe, self._maxsize, self._reader, self._writer,
self._rlock, self._wlock, self._sem, self._opid)
@ -279,10 +278,10 @@ def _feed(buffer, notempty, send_bytes, writelock, close, ignore_epipe):
class JoinableQueue(Queue):
def __init__(self, maxsize=0):
Queue.__init__(self, maxsize)
self._unfinished_tasks = synchronize.Semaphore(0)
self._cond = synchronize.Condition()
def __init__(self, maxsize=0, *, ctx):
Queue.__init__(self, maxsize, ctx=ctx)
self._unfinished_tasks = ctx.Semaphore(0)
self._cond = ctx.Condition()
def __getstate__(self):
return Queue.__getstate__(self) + (self._cond, self._unfinished_tasks)
@ -332,20 +331,20 @@ def join(self):
class SimpleQueue(object):
def __init__(self):
def __init__(self, *, ctx):
self._reader, self._writer = connection.Pipe(duplex=False)
self._rlock = synchronize.Lock()
self._rlock = ctx.Lock()
self._poll = self._reader.poll
if sys.platform == 'win32':
self._wlock = None
else:
self._wlock = synchronize.Lock()
self._wlock = ctx.Lock()
def empty(self):
return not self._poll()
def __getstate__(self):
popen.assert_spawning(self)
context.assert_spawning(self)
return (self._reader, self._writer, self._rlock, self._wlock)
def __setstate__(self, state):

4
Lib/multiprocessing/reduction.py
View file

@ -15,7 +15,7 @@
import socket
import sys
from . import popen
from . import context
from . import util
__all__ = ['send_handle', 'recv_handle', 'ForkingPickler', 'register', 'dump']
@ -183,7 +183,7 @@ def recv_handle(conn):
def DupFd(fd):
'''Return a wrapper for an fd.'''
popen_obj = popen.get_spawning_popen()
popen_obj = context.get_spawning_popen()
if popen_obj is not None:
return popen_obj.DupFd(popen_obj.duplicate_for_child(fd))
elif HAVE_SEND_HANDLE:

114
Lib/multiprocessing/semaphore_tracker.py
View file

@ -26,60 +26,70 @@
__all__ = ['ensure_running', 'register', 'unregister']
_semaphore_tracker_fd = None
_lock = threading.Lock()
class SemaphoreTracker(object):
def __init__(self):
self._lock = threading.Lock()
self._fd = None
def getfd(self):
self.ensure_running()
return self._fd
def ensure_running(self):
'''Make sure that semaphore tracker process is running.
This can be run from any process. Usually a child process will use
the semaphore created by its parent.'''
with self._lock:
if self._fd is not None:
return
fds_to_pass = []
try:
fds_to_pass.append(sys.stderr.fileno())
except Exception:
pass
cmd = 'from multiprocessing.semaphore_tracker import main;main(%d)'
r, w = os.pipe()
try:
fds_to_pass.append(r)
# process will out live us, so no need to wait on pid
exe = spawn.get_executable()
args = [exe] + util._args_from_interpreter_flags()
args += ['-c', cmd % r]
util.spawnv_passfds(exe, args, fds_to_pass)
except:
os.close(w)
raise
else:
self._fd = w
finally:
os.close(r)
def register(self, name):
'''Register name of semaphore with semaphore tracker.'''
self._send('REGISTER', name)
def unregister(self, name):
'''Unregister name of semaphore with semaphore tracker.'''
self._send('UNREGISTER', name)
def _send(self, cmd, name):
self.ensure_running()
msg = '{0}:{1}\n'.format(cmd, name).encode('ascii')
if len(name) > 512:
# posix guarantees that writes to a pipe of less than PIPE_BUF
# bytes are atomic, and that PIPE_BUF >= 512
raise ValueError('name too long')
nbytes = os.write(self._fd, msg)
assert nbytes == len(msg)
def ensure_running():
'''Make sure that semaphore tracker process is running.
This can be run from any process. Usually a child process will use
the semaphore created by its parent.'''
global _semaphore_tracker_fd
with _lock:
if _semaphore_tracker_fd is not None:
return
fds_to_pass = []
try:
fds_to_pass.append(sys.stderr.fileno())
except Exception:
pass
cmd = 'from multiprocessing.semaphore_tracker import main; main(%d)'
r, w = os.pipe()
try:
fds_to_pass.append(r)
# process will out live us, so no need to wait on pid
exe = spawn.get_executable()
args = [exe] + util._args_from_interpreter_flags()
args += ['-c', cmd % r]
util.spawnv_passfds(exe, args, fds_to_pass)
except:
os.close(w)
raise
else:
_semaphore_tracker_fd = w
finally:
os.close(r)
def register(name):
'''Register name of semaphore with semaphore tracker.'''
_send('REGISTER', name)
def unregister(name):
'''Unregister name of semaphore with semaphore tracker.'''
_send('UNREGISTER', name)
def _send(cmd, name):
msg = '{0}:{1}\n'.format(cmd, name).encode('ascii')
if len(name) > 512:
# posix guarantees that writes to a pipe of less than PIPE_BUF
# bytes are atomic, and that PIPE_BUF >= 512
raise ValueError('name too long')
nbytes = os.write(_semaphore_tracker_fd, msg)
assert nbytes == len(msg)
_semaphore_tracker = SemaphoreTracker()
ensure_running = _semaphore_tracker.ensure_running
register = _semaphore_tracker.register
unregister = _semaphore_tracker.unregister
getfd = _semaphore_tracker.getfd
def main(fd):

37
Lib/multiprocessing/sharedctypes.py
View file

@ -11,10 +11,10 @@
import weakref
from . import heap
from . import get_context
from .synchronize import RLock
from .context import assert_spawning
from .reduction import ForkingPickler
from .popen import assert_spawning
__all__ = ['RawValue', 'RawArray', 'Value', 'Array', 'copy', 'synchronized']
@ -66,7 +66,7 @@ def RawArray(typecode_or_type, size_or_initializer):
result.__init__(*size_or_initializer)
return result
def Value(typecode_or_type, *args, lock=True):
def Value(typecode_or_type, *args, lock=True, ctx=None):
'''
Return a synchronization wrapper for a Value
'''
@ -74,12 +74,13 @@ def Value(typecode_or_type, *args, lock=True):
if lock is False:
return obj
if lock in (True, None):
lock = RLock()
ctx = ctx or get_context()
lock = ctx.RLock()
if not hasattr(lock, 'acquire'):
raise AttributeError("'%r' has no method 'acquire'" % lock)
return synchronized(obj, lock)
return synchronized(obj, lock, ctx=ctx)
def Array(typecode_or_type, size_or_initializer, *, lock=True):
def Array(typecode_or_type, size_or_initializer, *, lock=True, ctx=None):
'''
Return a synchronization wrapper for a RawArray
'''
@ -87,25 +88,27 @@ def Array(typecode_or_type, size_or_initializer, *, lock=True):
if lock is False:
return obj
if lock in (True, None):
lock = RLock()
ctx = ctx or get_context()
lock = ctx.RLock()
if not hasattr(lock, 'acquire'):
raise AttributeError("'%r' has no method 'acquire'" % lock)
return synchronized(obj, lock)
return synchronized(obj, lock, ctx=ctx)
def copy(obj):
new_obj = _new_value(type(obj))
ctypes.pointer(new_obj)[0] = obj
return new_obj
def synchronized(obj, lock=None):
def synchronized(obj, lock=None, ctx=None):
assert not isinstance(obj, SynchronizedBase), 'object already synchronized'
ctx = ctx or get_context()
if isinstance(obj, ctypes._SimpleCData):
return Synchronized(obj, lock)
return Synchronized(obj, lock, ctx)
elif isinstance(obj, ctypes.Array):
if obj._type_ is ctypes.c_char:
return SynchronizedString(obj, lock)
return SynchronizedArray(obj, lock)
return SynchronizedString(obj, lock, ctx)
return SynchronizedArray(obj, lock, ctx)
else:
cls = type(obj)
try:
@ -115,7 +118,7 @@ def synchronized(obj, lock=None):
d = dict((name, make_property(name)) for name in names)
classname = 'Synchronized' + cls.__name__
scls = class_cache[cls] = type(classname, (SynchronizedBase,), d)
return scls(obj, lock)
return scls(obj, lock, ctx)
#
# Functions for pickling/unpickling
@ -175,9 +178,13 @@ def set%s(self, value):
class SynchronizedBase(object):
def __init__(self, obj, lock=None):
def __init__(self, obj, lock=None, ctx=None):
self._obj = obj
self._lock = lock or RLock()
if lock:
self._lock = lock
else:
ctx = ctx or get_context(force=True)
self._lock = ctx.RLock()
self.acquire = self._lock.acquire
self.release = self._lock.release

8
Lib/multiprocessing/spawn.py
View file

@ -12,9 +12,9 @@
import pickle
import sys
from . import get_start_method, set_start_method
from . import process
from . import util
from . import popen
__all__ = ['_main', 'freeze_support', 'set_executable', 'get_executable',
'get_preparation_data', 'get_command_line', 'import_main_path']
@ -91,7 +91,7 @@ def spawn_main(pipe_handle, parent_pid=None, tracker_fd=None):
fd = msvcrt.open_osfhandle(new_handle, os.O_RDONLY)
else:
from . import semaphore_tracker
semaphore_tracker._semaphore_tracker_fd = tracker_fd
semaphore_tracker._semaphore_tracker._fd = tracker_fd
fd = pipe_handle
exitcode = _main(fd)
sys.exit(exitcode)
@ -154,7 +154,7 @@ def get_preparation_data(name):
sys_argv=sys.argv,
orig_dir=process.ORIGINAL_DIR,
dir=os.getcwd(),
start_method=popen.get_start_method(),
start_method=get_start_method(),
)
if sys.platform != 'win32' or (not WINEXE and not WINSERVICE):
@ -204,7 +204,7 @@ def prepare(data):
process.ORIGINAL_DIR = data['orig_dir']
if 'start_method' in data:
popen.set_start_method(data['start_method'], start_helpers=False)
set_start_method(data['start_method'])
if 'main_path' in data:
import_main_path(data['main_path'])

53
Lib/multiprocessing/synchronize.py
View file

@ -20,7 +20,7 @@
from time import time as _time
from . import popen
from . import context
from . import process
from . import util
@ -50,14 +50,15 @@ class SemLock(object):
_rand = tempfile._RandomNameSequence()
def __init__(self, kind, value, maxvalue):
unlink_immediately = (sys.platform == 'win32' or
popen.get_start_method() == 'fork')
def __init__(self, kind, value, maxvalue, *, ctx):
ctx = ctx or get_context()
ctx = ctx.get_context()
unlink_now = sys.platform == 'win32' or ctx._name == 'fork'
for i in range(100):
try:
sl = self._semlock = _multiprocessing.SemLock(
kind, value, maxvalue, self._make_name(),
unlink_immediately)
unlink_now)
except FileExistsError:
pass
else:
@ -99,10 +100,10 @@ def __exit__(self, *args):
return self._semlock.__exit__(*args)
def __getstate__(self):
popen.assert_spawning(self)
context.assert_spawning(self)
sl = self._semlock
if sys.platform == 'win32':
h = popen.get_spawning_popen().duplicate_for_child(sl.handle)
h = context.get_spawning_popen().duplicate_for_child(sl.handle)
else:
h = sl.handle
return (h, sl.kind, sl.maxvalue, sl.name)
@ -123,8 +124,8 @@ def _make_name():
class Semaphore(SemLock):
def __init__(self, value=1):
SemLock.__init__(self, SEMAPHORE, value, SEM_VALUE_MAX)
def __init__(self, value=1, *, ctx):
SemLock.__init__(self, SEMAPHORE, value, SEM_VALUE_MAX, ctx=ctx)
def get_value(self):
return self._semlock._get_value()
@ -142,8 +143,8 @@ def __repr__(self):
class BoundedSemaphore(Semaphore):
def __init__(self, value=1):
SemLock.__init__(self, SEMAPHORE, value, value)
def __init__(self, value=1, *, ctx):
SemLock.__init__(self, SEMAPHORE, value, value, ctx=ctx)
def __repr__(self):
try:
@ -159,8 +160,8 @@ def __repr__(self):
class Lock(SemLock):
def __init__(self):
SemLock.__init__(self, SEMAPHORE, 1, 1)
def __init__(self, *, ctx):
SemLock.__init__(self, SEMAPHORE, 1, 1, ctx=ctx)
def __repr__(self):
try:
@ -184,8 +185,8 @@ def __repr__(self):
class RLock(SemLock):
def __init__(self):
SemLock.__init__(self, RECURSIVE_MUTEX, 1, 1)
def __init__(self, *, ctx):
SemLock.__init__(self, RECURSIVE_MUTEX, 1, 1, ctx=ctx)
def __repr__(self):
try:
@ -210,15 +211,15 @@ def __repr__(self):
class Condition(object):
def __init__(self, lock=None):
self._lock = lock or RLock()
self._sleeping_count = Semaphore(0)
self._woken_count = Semaphore(0)
self._wait_semaphore = Semaphore(0)
def __init__(self, lock=None, *, ctx):
self._lock = lock or ctx.RLock()
self._sleeping_count = ctx.Semaphore(0)
self._woken_count = ctx.Semaphore(0)
self._wait_semaphore = ctx.Semaphore(0)
self._make_methods()
def __getstate__(self):
popen.assert_spawning(self)
context.assert_spawning(self)
return (self._lock, self._sleeping_count,
self._woken_count, self._wait_semaphore)
@ -332,9 +333,9 @@ def wait_for(self, predicate, timeout=None):
class Event(object):
def __init__(self):
self._cond = Condition(Lock())
self._flag = Semaphore(0)
def __init__(self, *, ctx):
self._cond = ctx.Condition(ctx.Lock())
self._flag = ctx.Semaphore(0)
def is_set(self):
self._cond.acquire()
@ -383,11 +384,11 @@ def wait(self, timeout=None):
class Barrier(threading.Barrier):
def __init__(self, parties, action=None, timeout=None):
def __init__(self, parties, action=None, timeout=None, *, ctx):
import struct
from .heap import BufferWrapper
wrapper = BufferWrapper(struct.calcsize('i') * 2)
cond = Condition()
cond = ctx.Condition()
self.__setstate__((parties, action, timeout, cond, wrapper))
self._state = 0
self._count = 0

42
Lib/test/_test_multiprocessing.py
View file

@ -3555,6 +3555,32 @@ def test_ignore_listener(self):
conn.close()
class TestStartMethod(unittest.TestCase):
@classmethod
def _check_context(cls, conn):
conn.send(multiprocessing.get_start_method())
def check_context(self, ctx):
r, w = ctx.Pipe(duplex=False)
p = ctx.Process(target=self._check_context, args=(w,))
p.start()
w.close()
child_method = r.recv()
r.close()
p.join()
self.assertEqual(child_method, ctx.get_start_method())
def test_context(self):
for method in ('fork', 'spawn', 'forkserver'):
try:
ctx = multiprocessing.get_context(method)
except ValueError:
continue
self.assertEqual(ctx.get_start_method(), method)
self.assertIs(ctx.get_context(), ctx)
self.assertRaises(ValueError, ctx.set_start_method, 'spawn')
self.assertRaises(ValueError, ctx.set_start_method, None)
self.check_context(ctx)
def test_set_get(self):
multiprocessing.set_forkserver_preload(PRELOAD)
count = 0
@ -3562,13 +3588,19 @@ def test_set_get(self):
try:
for method in ('fork', 'spawn', 'forkserver'):
try:
multiprocessing.set_start_method(method)
multiprocessing.set_start_method(method, force=True)
except ValueError:
continue
self.assertEqual(multiprocessing.get_start_method(), method)
ctx = multiprocessing.get_context()
self.assertEqual(ctx.get_start_method(), method)
self.assertTrue(type(ctx).__name__.lower().startswith(method))
self.assertTrue(
ctx.Process.__name__.lower().startswith(method))
self.check_context(multiprocessing)
count += 1
finally:
multiprocessing.set_start_method(old_method)
multiprocessing.set_start_method(old_method, force=True)
self.assertGreaterEqual(count, 1)
def test_get_all(self):
@ -3753,9 +3785,9 @@ def setUpModule():
multiprocessing.process._cleanup()
dangling[0] = multiprocessing.process._dangling.copy()
dangling[1] = threading._dangling.copy()
old_start_method[0] = multiprocessing.get_start_method()
old_start_method[0] = multiprocessing.get_start_method(allow_none=True)
try:
multiprocessing.set_start_method(start_method)
multiprocessing.set_start_method(start_method, force=True)
except ValueError:
raise unittest.SkipTest(start_method +
' start method not supported')
@ -3771,7 +3803,7 @@ def setUpModule():
multiprocessing.get_logger().setLevel(LOG_LEVEL)
def tearDownModule():
multiprocessing.set_start_method(old_start_method[0])
multiprocessing.set_start_method(old_start_method[0], force=True)
# pause a bit so we don't get warning about dangling threads/processes
time.sleep(0.5)
multiprocessing.process._cleanup()