Staging
v0.5.1
v0.5.1
https://github.com/python/cpython
Tip revision: 1da43e5e916949c8e849e656d9d05fa4b9d6836c authored by Benjamin Peterson on 26 June 2009, 13:21:52 UTC
rearrange the sections of the README, so they'll hopefully be more in the order people will interested in
rearrange the sections of the README, so they'll hopefully be more in the order people will interested in
Tip revision: 1da43e5
process.py
#
# 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
#
# 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
@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._daemonic
@daemon.setter
def daemon(self, daemonic):
'''
Set whether process is a daemon
'''
assert self._popen is None, 'process has already started'
self._daemonic = daemonic
@property
def authkey(self):
return self._authkey
@authkey.setter
def authkey(self, authkey):
'''
Set authorization key of process
'''
self._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 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 = 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.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)
if sys.stdin is not None:
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.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