Edit File: process.py
# # Module providing the `Process` class which emulates `threading.Thread` # # multiprocessing/process.py # # Copyright (c) 2006-2008, R Oudkerk # Licensed to PSF under a Contributor Agreement. # __all__ = ['BaseProcess', 'current_process', 'active_children'] # # Imports # import os import sys import signal import itertools from _weakrefset import WeakSet # # # try: ORIGINAL_DIR = os.path.abspath(os.getcwd()) except OSError: ORIGINAL_DIR = None # # Public functions # def current_process(): ''' Return process object representing the current process ''' return _current_process def active_children(): ''' Return list of process objects corresponding to live child processes ''' _cleanup() return list(_children) # # # def _cleanup(): # check for processes which have finished for p in list(_children): if p._popen.poll() is not None: _children.discard(p) # # The `Process` class # class BaseProcess(object): ''' Process objects represent activity that is run in a separate process The class is analogous to `threading.Thread` ''' def _Popen(self): raise NotImplementedError def __init__(self, group=None, target=None, name=None, args=(), kwargs={}, *, daemon=None): assert group is None, 'group argument must be None for now' count = next(_process_counter) self._identity = _current_process._identity + (count,) self._config = _current_process._config.copy() self._parent_pid = os.getpid() self._popen = None self._target = target self._args = tuple(args) self._kwargs = dict(kwargs) self._name = name or type(self).__name__ + '-' + \ ':'.join(str(i) for i in self._identity) if daemon is not None: self.daemon = daemon _dangling.add(self) def run(self): ''' Method to be run in sub-process; can be overridden in sub-class ''' if self._target: self._target(*self._args, **self._kwargs) def start(self): ''' Start child process ''' assert self._popen is None, 'cannot start a process twice' assert self._parent_pid == os.getpid(), \ 'can only start a process object created by current process' assert not _current_process._config.get('daemon'), \ 'daemonic processes are not allowed to have children' _cleanup() self._popen = self._Popen(self) self._sentinel = self._popen.sentinel # Avoid a refcycle if the target function holds an indirect # reference to the process object (see bpo-30775) del self._target, self._args, self._kwargs _children.add(self) def terminate(self): ''' Terminate process; sends SIGTERM signal or uses TerminateProcess() ''' self._popen.terminate() def join(self, timeout=None): ''' Wait until child process terminates ''' assert self._parent_pid == os.getpid(), 'can only join a child process' assert self._popen is not None, 'can only join a started process' res = self._popen.wait(timeout) if res is not None: _children.discard(self) def is_alive(self): ''' Return whether process is alive ''' if self is _current_process: return True assert self._parent_pid == os.getpid(), 'can only test a child process' if self._popen is None: return False returncode = self._popen.poll() if returncode is None: return True else: _children.discard(self) return False @property def name(self): return self._name @name.setter def name(self, name): assert isinstance(name, str), 'name must be a string' self._name = name @property def daemon(self): ''' Return whether process is a daemon ''' return self._config.get('daemon', False) @daemon.setter def daemon(self, daemonic): ''' Set whether process is a daemon ''' assert self._popen is None, 'process has already started' self._config['daemon'] = daemonic @property def authkey(self): return self._config['authkey'] @authkey.setter def authkey(self, authkey): ''' Set authorization key of process ''' self._config['authkey'] = AuthenticationString(authkey) @property def exitcode(self): ''' Return exit code of process or `None` if it has yet to stop ''' if self._popen is None: return self._popen return self._popen.poll() @property def ident(self): ''' Return identifier (PID) of process or `None` if it has yet to start ''' if self is _current_process: return os.getpid() else: return self._popen and self._popen.pid pid = ident @property def sentinel(self): ''' Return a file descriptor (Unix) or handle (Windows) suitable for waiting for process termination. ''' try: return self._sentinel except AttributeError: raise ValueError("process not started") def __repr__(self): if self is _current_process: status = 'started' elif self._parent_pid != os.getpid(): status = 'unknown' elif self._popen is None: status = 'initial' else: if self._popen.poll() is not None: status = self.exitcode else: status = 'started' if type(status) is int: if status == 0: status = 'stopped' else: status = 'stopped[%s]' % _exitcode_to_name.get(status, status) return '<%s(%s, %s%s)>' % (type(self).__name__, self._name, status, self.daemon and ' daemon' or '') ## def _bootstrap(self): 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() util._close_stdin() old_process = _current_process _current_process = self try: util._finalizer_registry.clear() util._run_after_forkers() finally: # delay finalization of the old process object until after # _run_after_forkers() is executed del old_process util.info('child process calling self.run()') try: self.run() exitcode = 0 finally: util._exit_function() except SystemExit as e: if not e.args: exitcode = 1 elif isinstance(e.args[0], int): exitcode = e.args[0] else: sys.stderr.write(str(e.args[0]) + '\n') exitcode = 1 except: exitcode = 1 import traceback sys.stderr.write('Process %s:\n' % self.name) traceback.print_exc() finally: util.info('process exiting with exitcode %d' % exitcode) util._flush_std_streams() return exitcode # # We subclass bytes to avoid accidental transmission of auth keys over network # class AuthenticationString(bytes): def __reduce__(self): from .context import get_spawning_popen if get_spawning_popen() is None: raise TypeError( 'Pickling an AuthenticationString object is ' 'disallowed for security reasons' ) return AuthenticationString, (bytes(self),) # # Create object representing the main process # class _MainProcess(BaseProcess): def __init__(self): self._identity = () self._name = 'MainProcess' self._parent_pid = None self._popen = None self._config = {'authkey': AuthenticationString(os.urandom(32)), 'semprefix': '/mp'} # Note that some versions of FreeBSD only allow named # semaphores to have names of up to 14 characters. Therefore # we choose a short prefix. # # On MacOSX in a sandbox it may be necessary to use a # different prefix -- see #19478. # # Everything in self._config will be inherited by descendant # processes. _current_process = _MainProcess() _process_counter = itertools.count(1) _children = set() del _MainProcess # # Give names to some return codes # _exitcode_to_name = {} for name, signum in list(signal.__dict__.items()): if name[:3]=='SIG' and '_' not in name: _exitcode_to_name[-signum] = name # For debug and leak testing _dangling = WeakSet()
Back to File Manager