mirror of
https://github.com/python/cpython.git
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59d5404bc7
In Python 3.2 and earlier, Process.join() and Connection.poll() treated negative timeouts as zero timeouts. Earlier versions from the 3.3 line of development treat them as infinite timeouts. The patch reverts to the old behaviour.
466 lines
14 KiB
Python
466 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', 'exit', '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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exit = os._exit
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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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exit = _winapi.ExitProcess
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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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# 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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# start process
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cmd = get_command_line() + [rhandle]
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cmd = ' '.join('"%s"' % x for x in cmd)
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hp, ht, pid, tid = _winapi.CreateProcess(
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_python_exe, cmd, None, None, 1, 0, None, None, None
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)
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_winapi.CloseHandle(ht)
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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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# send information to child
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prep_data = get_preparation_data(process_obj._name)
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to_child = os.fdopen(wfd, 'wb')
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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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to_child.close()
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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 WindowsError:
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if self.wait(timeout=0.1) 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 process.current_process()._identity==() and is_forking(sys.argv):
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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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return [_python_exe, '-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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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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