| # |
| # 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', |
| 'parent_process'] |
| |
| # |
| # Imports |
| # |
| |
| import os |
| import sys |
| import signal |
| import itertools |
| import threading |
| 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 parent_process(): |
| ''' |
| Return process object representing the parent process |
| ''' |
| return _parent_process |
| |
| # |
| # |
| # |
| |
| 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._parent_name = _current_process.name |
| self._popen = None |
| self._closed = False |
| 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 _check_closed(self): |
| if self._closed: |
| raise ValueError("process object is closed") |
| |
| 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 |
| ''' |
| self._check_closed() |
| 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._check_closed() |
| self._popen.terminate() |
| |
| def kill(self): |
| ''' |
| Terminate process; sends SIGKILL signal or uses TerminateProcess() |
| ''' |
| self._check_closed() |
| self._popen.kill() |
| |
| def join(self, timeout=None): |
| ''' |
| Wait until child process terminates |
| ''' |
| self._check_closed() |
| 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 |
| ''' |
| self._check_closed() |
| 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 |
| |
| def close(self): |
| ''' |
| Close the Process object. |
| |
| This method releases resources held by the Process object. It is |
| an error to call this method if the child process is still running. |
| ''' |
| if self._popen is not None: |
| if self._popen.poll() is None: |
| raise ValueError("Cannot close a process while it is still running. " |
| "You should first call join() or terminate().") |
| self._popen.close() |
| self._popen = None |
| del self._sentinel |
| _children.discard(self) |
| self._closed = True |
| |
| @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 |
| ''' |
| self._check_closed() |
| 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 |
| ''' |
| self._check_closed() |
| 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. |
| ''' |
| self._check_closed() |
| try: |
| return self._sentinel |
| except AttributeError: |
| raise ValueError("process not started") from None |
| |
| def __repr__(self): |
| exitcode = None |
| if self is _current_process: |
| status = 'started' |
| elif self._closed: |
| status = 'closed' |
| elif self._parent_pid != os.getpid(): |
| status = 'unknown' |
| elif self._popen is None: |
| status = 'initial' |
| else: |
| exitcode = self._popen.poll() |
| if exitcode is not None: |
| status = 'stopped' |
| else: |
| status = 'started' |
| |
| info = [type(self).__name__, 'name=%r' % self._name] |
| if self._popen is not None: |
| info.append('pid=%s' % self._popen.pid) |
| info.append('parent=%s' % self._parent_pid) |
| info.append(status) |
| if exitcode is not None: |
| exitcode = _exitcode_to_name.get(exitcode, exitcode) |
| info.append('exitcode=%s' % exitcode) |
| if self.daemon: |
| info.append('daemon') |
| return '<%s>' % ' '.join(info) |
| |
| ## |
| |
| def _bootstrap(self, parent_sentinel=None): |
| from . import util, context |
| global _current_process, _parent_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 |
| _parent_process = _ParentProcess( |
| self._parent_name, self._parent_pid, parent_sentinel) |
| if threading._HAVE_THREAD_NATIVE_ID: |
| threading.main_thread()._set_native_id() |
| 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 e.code is None: |
| exitcode = 0 |
| elif isinstance(e.code, int): |
| exitcode = e.code |
| else: |
| sys.stderr.write(str(e.code) + '\n') |
| exitcode = 1 |
| except: |
| exitcode = 1 |
| import traceback |
| sys.stderr.write('Process %s:\n' % self.name) |
| traceback.print_exc() |
| finally: |
| threading._shutdown() |
| 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 parent process |
| # |
| |
| class _ParentProcess(BaseProcess): |
| |
| def __init__(self, name, pid, sentinel): |
| self._identity = () |
| self._name = name |
| self._pid = pid |
| self._parent_pid = None |
| self._popen = None |
| self._closed = False |
| self._sentinel = sentinel |
| self._config = {} |
| |
| def is_alive(self): |
| from multiprocessing.connection import wait |
| return not wait([self._sentinel], timeout=0) |
| |
| @property |
| def ident(self): |
| return self._pid |
| |
| def join(self, timeout=None): |
| ''' |
| Wait until parent process terminates |
| ''' |
| from multiprocessing.connection import wait |
| wait([self._sentinel], timeout=timeout) |
| |
| pid = ident |
| |
| # |
| # 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._closed = False |
| 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. |
| |
| def close(self): |
| pass |
| |
| |
| _parent_process = None |
| _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] = f'-{name}' |
| |
| # For debug and leak testing |
| _dangling = WeakSet() |
