Current File : //lib64/python2.7/multiprocessing/forking.py
#
# Module for starting a process object using os.fork() or CreateProcess()
#
# multiprocessing/forking.py
#
# 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.
#
import os
import sys
import signal
import errno
from multiprocessing import util, process
__all__ = ['Popen', 'assert_spawning', 'exit', 'duplicate', 'close', 'ForkingPickler']
#
# Check that the current thread is spawning a child process
#
def assert_spawning(self):
if not Popen.thread_is_spawning():
raise RuntimeError(
'%s objects should only be shared between processes'
' through inheritance' % type(self).__name__
)
#
# Try making some callable types picklable
#
from pickle import Pickler
class ForkingPickler(Pickler):
dispatch = Pickler.dispatch.copy()
@classmethod
def register(cls, type, reduce):
def dispatcher(self, obj):
rv = reduce(obj)
self.save_reduce(obj=obj, *rv)
cls.dispatch[type] = dispatcher
def _reduce_method(m):
if m.im_self is None:
return getattr, (m.im_class, m.im_func.func_name)
else:
return getattr, (m.im_self, m.im_func.func_name)
ForkingPickler.register(type(ForkingPickler.save), _reduce_method)
def _reduce_method_descriptor(m):
return getattr, (m.__objclass__, m.__name__)
ForkingPickler.register(type(list.append), _reduce_method_descriptor)
ForkingPickler.register(type(int.__add__), _reduce_method_descriptor)
#def _reduce_builtin_function_or_method(m):
# return getattr, (m.__self__, m.__name__)
#ForkingPickler.register(type(list().append), _reduce_builtin_function_or_method)
#ForkingPickler.register(type(int().__add__), _reduce_builtin_function_or_method)
try:
from functools import partial
except ImportError:
pass
else:
def _reduce_partial(p):
return _rebuild_partial, (p.func, p.args, p.keywords or {})
def _rebuild_partial(func, args, keywords):
return partial(func, *args, **keywords)
ForkingPickler.register(partial, _reduce_partial)
#
# Unix
#
if sys.platform != 'win32':
import time
exit = os._exit
duplicate = os.dup
close = os.close
#
# We define a Popen class similar to the one from subprocess, but
# whose constructor takes a process object as its argument.
#
class Popen(object):
def __init__(self, process_obj):
sys.stdout.flush()
sys.stderr.flush()
self.returncode = None
self.pid = os.fork()
if self.pid == 0:
if 'random' in sys.modules:
import random
random.seed()
code = process_obj._bootstrap()
sys.stdout.flush()
sys.stderr.flush()
os._exit(code)
def poll(self, flag=os.WNOHANG):
if self.returncode is None:
while True:
try:
pid, sts = os.waitpid(self.pid, flag)
except os.error as e:
if e.errno == errno.EINTR:
continue
# Child process not yet created. See #1731717
# e.errno == errno.ECHILD == 10
return None
else:
break
if pid == self.pid:
if os.WIFSIGNALED(sts):
self.returncode = -os.WTERMSIG(sts)
else:
assert os.WIFEXITED(sts)
self.returncode = os.WEXITSTATUS(sts)
return self.returncode
def wait(self, timeout=None):
if timeout is None:
return self.poll(0)
deadline = time.time() + timeout
delay = 0.0005
while 1:
res = self.poll()
if res is not None:
break
remaining = deadline - time.time()
if remaining <= 0:
break
delay = min(delay * 2, remaining, 0.05)
time.sleep(delay)
return res
def terminate(self):
if self.returncode is None:
try:
os.kill(self.pid, signal.SIGTERM)
except OSError, e:
if self.wait(timeout=0.1) is None:
raise
@staticmethod
def thread_is_spawning():
return False
#
# Windows
#
else:
import thread
import msvcrt
import _subprocess
import time
from _multiprocessing import win32, Connection, PipeConnection
from .util import Finalize
#try:
# from cPickle import dump, load, HIGHEST_PROTOCOL
#except ImportError:
from pickle import load, HIGHEST_PROTOCOL
def dump(obj, file, protocol=None):
ForkingPickler(file, protocol).dump(obj)
#
#
#
TERMINATE = 0x10000
WINEXE = (sys.platform == 'win32' and getattr(sys, 'frozen', False))
WINSERVICE = sys.executable.lower().endswith("pythonservice.exe")
exit = win32.ExitProcess
close = win32.CloseHandle
#
# _python_exe is the assumed path to the python executable.
# People embedding Python want to modify it.
#
if WINSERVICE:
_python_exe = os.path.join(sys.exec_prefix, 'python.exe')
else:
_python_exe = sys.executable
def set_executable(exe):
global _python_exe
_python_exe = exe
#
#
#
def duplicate(handle, target_process=None, inheritable=False):
if target_process is None:
target_process = _subprocess.GetCurrentProcess()
return _subprocess.DuplicateHandle(
_subprocess.GetCurrentProcess(), handle, target_process,
0, inheritable, _subprocess.DUPLICATE_SAME_ACCESS
).Detach()
#
# We define a Popen class similar to the one from subprocess, but
# whose constructor takes a process object as its argument.
#
class Popen(object):
'''
Start a subprocess to run the code of a process object
'''
_tls = thread._local()
def __init__(self, process_obj):
# create pipe for communication with child
rfd, wfd = os.pipe()
# get handle for read end of the pipe and make it inheritable
rhandle = duplicate(msvcrt.get_osfhandle(rfd), inheritable=True)
os.close(rfd)
# start process
cmd = get_command_line() + [rhandle]
cmd = ' '.join('"%s"' % x for x in cmd)
hp, ht, pid, tid = _subprocess.CreateProcess(
_python_exe, cmd, None, None, 1, 0, None, None, None
)
ht.Close()
close(rhandle)
# set attributes of self
self.pid = pid
self.returncode = None
self._handle = hp
# send information to child
prep_data = get_preparation_data(process_obj._name)
to_child = os.fdopen(wfd, 'wb')
Popen._tls.process_handle = int(hp)
try:
dump(prep_data, to_child, HIGHEST_PROTOCOL)
dump(process_obj, to_child, HIGHEST_PROTOCOL)
finally:
del Popen._tls.process_handle
to_child.close()
@staticmethod
def thread_is_spawning():
return getattr(Popen._tls, 'process_handle', None) is not None
@staticmethod
def duplicate_for_child(handle):
return duplicate(handle, Popen._tls.process_handle)
def wait(self, timeout=None):
if self.returncode is None:
if timeout is None:
msecs = _subprocess.INFINITE
else:
msecs = max(0, int(timeout * 1000 + 0.5))
res = _subprocess.WaitForSingleObject(int(self._handle), msecs)
if res == _subprocess.WAIT_OBJECT_0:
code = _subprocess.GetExitCodeProcess(self._handle)
if code == TERMINATE:
code = -signal.SIGTERM
self.returncode = code
return self.returncode
def poll(self):
return self.wait(timeout=0)
def terminate(self):
if self.returncode is None:
try:
_subprocess.TerminateProcess(int(self._handle), TERMINATE)
except WindowsError:
if self.wait(timeout=0.1) is None:
raise
#
#
#
def is_forking(argv):
'''
Return whether commandline indicates we are forking
'''
if len(argv) >= 2 and argv[1] == '--multiprocessing-fork':
assert len(argv) == 3
return True
else:
return False
def freeze_support():
'''
Run code for process object if this in not the main process
'''
if is_forking(sys.argv):
main()
sys.exit()
def get_command_line():
'''
Returns prefix of command line used for spawning a child process
'''
if getattr(process.current_process(), '_inheriting', False):
raise RuntimeError('''
Attempt to start a new process before the current process
has finished its bootstrapping phase.
This probably means that you are on Windows and you have
forgotten to use the proper idiom in the main module:
if __name__ == '__main__':
freeze_support()
...
The "freeze_support()" line can be omitted if the program
is not going to be frozen to produce a Windows executable.''')
if getattr(sys, 'frozen', False):
return [sys.executable, '--multiprocessing-fork']
else:
prog = 'from multiprocessing.forking import main; main()'
opts = util._args_from_interpreter_flags()
return [_python_exe] + opts + ['-c', prog, '--multiprocessing-fork']
def main():
'''
Run code specified by data received over pipe
'''
assert is_forking(sys.argv)
handle = int(sys.argv[-1])
fd = msvcrt.open_osfhandle(handle, os.O_RDONLY)
from_parent = os.fdopen(fd, 'rb')
process.current_process()._inheriting = True
preparation_data = load(from_parent)
prepare(preparation_data)
self = load(from_parent)
process.current_process()._inheriting = False
from_parent.close()
exitcode = self._bootstrap()
exit(exitcode)
def get_preparation_data(name):
'''
Return info about parent needed by child to unpickle process object
'''
from .util import _logger, _log_to_stderr
d = dict(
name=name,
sys_path=sys.path,
sys_argv=sys.argv,
log_to_stderr=_log_to_stderr,
orig_dir=process.ORIGINAL_DIR,
authkey=process.current_process().authkey,
)
if _logger is not None:
d['log_level'] = _logger.getEffectiveLevel()
if not WINEXE and not WINSERVICE and \
not d['sys_argv'][0].lower().endswith('pythonservice.exe'):
main_path = getattr(sys.modules['__main__'], '__file__', None)
if not main_path and sys.argv[0] not in ('', '-c'):
main_path = sys.argv[0]
if main_path is not None:
if not os.path.isabs(main_path) and \
process.ORIGINAL_DIR is not None:
main_path = os.path.join(process.ORIGINAL_DIR, main_path)
d['main_path'] = os.path.normpath(main_path)
return d
#
# Make (Pipe)Connection picklable
#
def reduce_connection(conn):
if not Popen.thread_is_spawning():
raise RuntimeError(
'By default %s objects can only be shared between processes\n'
'using inheritance' % type(conn).__name__
)
return type(conn), (Popen.duplicate_for_child(conn.fileno()),
conn.readable, conn.writable)
ForkingPickler.register(Connection, reduce_connection)
ForkingPickler.register(PipeConnection, reduce_connection)
#
# Prepare current process
#
old_main_modules = []
def prepare(data):
'''
Try to get current process ready to unpickle process object
'''
old_main_modules.append(sys.modules['__main__'])
if 'name' in data:
process.current_process().name = data['name']
if 'authkey' in data:
process.current_process()._authkey = data['authkey']
if 'log_to_stderr' in data and data['log_to_stderr']:
util.log_to_stderr()
if 'log_level' in data:
util.get_logger().setLevel(data['log_level'])
if 'sys_path' in data:
sys.path = data['sys_path']
if 'sys_argv' in data:
sys.argv = data['sys_argv']
if 'dir' in data:
os.chdir(data['dir'])
if 'orig_dir' in data:
process.ORIGINAL_DIR = data['orig_dir']
if 'main_path' in data:
# XXX (ncoghlan): The following code makes several bogus
# assumptions regarding the relationship between __file__
# and a module's real name. See PEP 302 and issue #10845
# The problem is resolved properly in Python 3.4+, as
# described in issue #19946
main_path = data['main_path']
main_name = os.path.splitext(os.path.basename(main_path))[0]
if main_name == '__init__':
main_name = os.path.basename(os.path.dirname(main_path))
if main_name == '__main__':
# For directory and zipfile execution, we assume an implicit
# "if __name__ == '__main__':" around the module, and don't
# rerun the main module code in spawned processes
main_module = sys.modules['__main__']
main_module.__file__ = main_path
elif main_name != 'ipython':
# Main modules not actually called __main__.py may
# contain additional code that should still be executed
import imp
if main_path is None:
dirs = None
elif os.path.basename(main_path).startswith('__init__.py'):
dirs = [os.path.dirname(os.path.dirname(main_path))]
else:
dirs = [os.path.dirname(main_path)]
assert main_name not in sys.modules, main_name
file, path_name, etc = imp.find_module(main_name, dirs)
try:
# We would like to do "imp.load_module('__main__', ...)"
# here. However, that would cause 'if __name__ ==
# "__main__"' clauses to be executed.
main_module = imp.load_module(
'__parents_main__', file, path_name, etc
)
finally:
if file:
file.close()
sys.modules['__main__'] = main_module
main_module.__name__ = '__main__'
# Try to make the potentially picklable objects in
# sys.modules['__main__'] realize they are in the main
# module -- somewhat ugly.
for obj in main_module.__dict__.values():
try:
if obj.__module__ == '__parents_main__':
obj.__module__ = '__main__'
except Exception:
pass
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