469 lines
14 KiB
Python
469 lines
14 KiB
Python
#
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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
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# Licensed to PSF under a Contributor Agreement.
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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', 'duplicate', 'close', 'ForkingPickler']
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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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# Try making some callable types picklable
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#
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from pickle import Pickler
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from copyreg import dispatch_table
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class ForkingPickler(Pickler):
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_extra_reducers = {}
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def __init__(self, *args):
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Pickler.__init__(self, *args)
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self.dispatch_table = dispatch_table.copy()
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self.dispatch_table.update(self._extra_reducers)
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@classmethod
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def register(cls, type, reduce):
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cls._extra_reducers[type] = reduce
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def _reduce_method(m):
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if m.__self__ is None:
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return getattr, (m.__class__, m.__func__.__name__)
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else:
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return getattr, (m.__self__, m.__func__.__name__)
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class _C:
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def f(self):
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pass
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ForkingPickler.register(type(_C().f), _reduce_method)
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def _reduce_method_descriptor(m):
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return getattr, (m.__objclass__, m.__name__)
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ForkingPickler.register(type(list.append), _reduce_method_descriptor)
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ForkingPickler.register(type(int.__add__), _reduce_method_descriptor)
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try:
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from functools import partial
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except ImportError:
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pass
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else:
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def _reduce_partial(p):
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return _rebuild_partial, (p.func, p.args, p.keywords or {})
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def _rebuild_partial(func, args, keywords):
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return partial(func, *args, **keywords)
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ForkingPickler.register(partial, _reduce_partial)
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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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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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r, w = os.pipe()
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self.sentinel = r
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self.pid = os.fork()
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if self.pid == 0:
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os.close(r)
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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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os._exit(code)
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# `w` will be closed when the child exits, at which point `r`
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# will become ready for reading (using e.g. select()).
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os.close(w)
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util.Finalize(self, os.close, (r,))
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def poll(self, flag=os.WNOHANG):
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if self.returncode is None:
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try:
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pid, sts = os.waitpid(self.pid, flag)
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except os.error:
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# Child process not yet created. See #1731717
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# e.errno == errno.ECHILD == 10
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return None
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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 self.returncode is None:
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if timeout is not None:
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from .connection import wait
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if not wait([self.sentinel], timeout):
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return None
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# This shouldn't block if wait() returned successfully.
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return self.poll(os.WNOHANG if timeout == 0.0 else 0)
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return self.returncode
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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:
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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 _winapi
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from pickle import load, HIGHEST_PROTOCOL
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def dump(obj, file, protocol=None):
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ForkingPickler(file, protocol).dump(obj)
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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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WINSERVICE = sys.executable.lower().endswith("pythonservice.exe")
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close = _winapi.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 WINSERVICE:
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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 = _winapi.GetCurrentProcess()
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return _winapi.DuplicateHandle(
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_winapi.GetCurrentProcess(), handle, target_process,
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0, inheritable, _winapi.DUPLICATE_SAME_ACCESS
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)
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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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cmd = ' '.join('"%s"' % x for x in get_command_line())
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prep_data = get_preparation_data(process_obj._name)
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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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with open(wfd, 'wb', closefd=True) as to_child:
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# start process
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try:
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hp, ht, pid, tid = _winapi.CreateProcess(
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_python_exe, cmd + (' %s' % rhandle),
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None, None, 1, 0, None, None, None
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)
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_winapi.CloseHandle(ht)
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finally:
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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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self.sentinel = int(hp)
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util.Finalize(self, _winapi.CloseHandle, (self.sentinel,))
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# send information to child
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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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@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 = _winapi.INFINITE
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else:
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msecs = max(0, int(timeout * 1000 + 0.5))
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res = _winapi.WaitForSingleObject(int(self._handle), msecs)
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if res == _winapi.WAIT_OBJECT_0:
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code = _winapi.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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_winapi.TerminateProcess(int(self._handle), TERMINATE)
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except OSError:
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if self.wait(timeout=1.0) 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 getattr(process.current_process(), '_inheriting', False):
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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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opts = util._args_from_interpreter_flags()
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return [_python_exe] + opts + ['-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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sys.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().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 and not WINSERVICE:
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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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# 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().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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# XXX (ncoghlan): The following code makes several bogus
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# assumptions regarding the relationship between __file__
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# and a module's real name. See PEP 302 and issue #10845
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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 == '__main__':
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main_module = sys.modules['__main__']
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main_module.__file__ = main_path
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elif main_name != 'ipython':
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# Main modules not actually called __main__.py may
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# contain additional code that should still be executed
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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 list(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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