# # Module providing the `Process` class which emulates `threading.Thread` # # multiprocessing/process.py # # Copyright (c) 2006-2008, R Oudkerk --- see COPYING.txt # __all__ = ['Process', 'current_process', 'active_children'] # # Imports # import os import sys import signal import itertools # # # try: ORIGINAL_DIR = os.path.abspath(os.getcwd()) except OSError: ORIGINAL_DIR = None try: bytes except NameError: bytes = str # XXX not needed in Py2.6 and Py3.0 # # 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(_current_process._children) # # # def _cleanup(): # check for processes which have finished for p in list(_current_process._children): if p._popen.poll() is not None: _current_process._children.discard(p) # # The `Process` class # class Process(object): ''' Process objects represent activity that is run in a separate process The class is analagous to `threading.Thread` ''' _Popen = None def __init__(self, group=None, target=None, name=None, args=(), kwargs={}): assert group is None, 'group argument must be None for now' count = next(_current_process._counter) self._identity = _current_process._identity + (count,) self._authkey = _current_process._authkey self._daemonic = _current_process._daemonic self._tempdir = _current_process._tempdir 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) 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._daemonic, \ 'daemonic processes are not allowed to have children' _cleanup() if self._Popen is not None: Popen = self._Popen else: from .forking import Popen self._popen = Popen(self) _current_process._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: _current_process._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 self._popen.poll() return self._popen.returncode is None def get_name(self): ''' Return name of process ''' return self._name def set_name(self, name): ''' Set name of process ''' assert isinstance(name, str), 'name must be a string' self._name = name def is_daemon(self): ''' Return whether process is a daemon ''' return self._daemonic def set_daemon(self, daemonic): ''' Set whether process is a daemon ''' assert self._popen is None, 'process has already started' self._daemonic = daemonic def get_authkey(self): ''' Return authorization key of process ''' return self._authkey def set_authkey(self, authkey): ''' Set authorization key of process ''' self._authkey = AuthenticationString(authkey) def get_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() def get_ident(self): ''' Return indentifier (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 = property(get_ident) 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.get_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._daemonic and ' daemon' or '') ## def _bootstrap(self): from . import util global _current_process try: self._children = set() self._counter = itertools.count(1) try: os.close(sys.stdin.fileno()) except (OSError, ValueError): pass _current_process = self util._finalizer_registry.clear() util._run_after_forkers() 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 type(e.args[0]) is int: exitcode = e.args[0] else: sys.stderr.write(e.args[0] + '\n') sys.stderr.flush() exitcode = 1 except: exitcode = 1 import traceback sys.stderr.write('Process %s:\n' % self.get_name()) sys.stderr.flush() traceback.print_exc() util.info('process exiting with exitcode %d' % exitcode) return exitcode # # We subclass bytes to avoid accidental transmission of auth keys over network # class AuthenticationString(bytes): def __reduce__(self): from .forking import Popen if not Popen.thread_is_spawning(): raise TypeError( 'Pickling an AuthenticationString object is ' 'disallowed for security reasons' ) return AuthenticationString, (bytes(self),) # # Create object representing the main process # class _MainProcess(Process): def __init__(self): self._identity = () self._daemonic = False self._name = 'MainProcess' self._parent_pid = None self._popen = None self._counter = itertools.count(1) self._children = set() self._authkey = AuthenticationString(os.urandom(32)) self._tempdir = None _current_process = _MainProcess() 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