Python code coverage for Lib/multiprocessing/process.py

#	count	content
1	n/a	#
2	n/a	# Module providing the `Process` class which emulates `threading.Thread`
3	n/a	#
4	n/a	# multiprocessing/process.py
5	n/a	#
6	n/a	# Copyright (c) 2006-2008, R Oudkerk
7	n/a	# Licensed to PSF under a Contributor Agreement.
8	n/a	#
9	n/a
10	n/a	__all__ = ['BaseProcess', 'current_process', 'active_children']
11	n/a
12	n/a	#
13	n/a	# Imports
14	n/a	#
15	n/a
16	n/a	import os
17	n/a	import sys
18	n/a	import signal
19	n/a	import itertools
20	n/a	from _weakrefset import WeakSet
21	n/a
22	n/a	#
23	n/a	#
24	n/a	#
25	n/a
26	n/a	try:
27	n/a	ORIGINAL_DIR = os.path.abspath(os.getcwd())
28	n/a	except OSError:
29	n/a	ORIGINAL_DIR = None
30	n/a
31	n/a	#
32	n/a	# Public functions
33	n/a	#
34	n/a
35	n/a	def current_process():
36	n/a	'''
37	n/a	Return process object representing the current process
38	n/a	'''
39	n/a	return _current_process
40	n/a
41	n/a	def active_children():
42	n/a	'''
43	n/a	Return list of process objects corresponding to live child processes
44	n/a	'''
45	n/a	_cleanup()
46	n/a	return list(_children)
47	n/a
48	n/a	#
49	n/a	#
50	n/a	#
51	n/a
52	n/a	def _cleanup():
53	n/a	# check for processes which have finished
54	n/a	for p in list(_children):
55	n/a	if p._popen.poll() is not None:
56	n/a	_children.discard(p)
57	n/a
58	n/a	#
59	n/a	# The `Process` class
60	n/a	#
61	n/a
62	n/a	class BaseProcess(object):
63	n/a	'''
64	n/a	Process objects represent activity that is run in a separate process
65	n/a
66	n/a	The class is analogous to `threading.Thread`
67	n/a	'''
68	n/a	def _Popen(self):
69	n/a	raise NotImplementedError
70	n/a
71	n/a	def __init__(self, group=None, target=None, name=None, args=(), kwargs={},
72	n/a	*, daemon=None):
73	n/a	assert group is None, 'group argument must be None for now'
74	n/a	count = next(_process_counter)
75	n/a	self._identity = _current_process._identity + (count,)
76	n/a	self._config = _current_process._config.copy()
77	n/a	self._parent_pid = os.getpid()
78	n/a	self._popen = None
79	n/a	self._target = target
80	n/a	self._args = tuple(args)
81	n/a	self._kwargs = dict(kwargs)
82	n/a	self._name = name or type(self).__name__ + '-' + \
83	n/a	':'.join(str(i) for i in self._identity)
84	n/a	if daemon is not None:
85	n/a	self.daemon = daemon
86	n/a	_dangling.add(self)
87	n/a
88	n/a	def run(self):
89	n/a	'''
90	n/a	Method to be run in sub-process; can be overridden in sub-class
91	n/a	'''
92	n/a	if self._target:
93	n/a	self._target(self._args, *self._kwargs)
94	n/a
95	n/a	def start(self):
96	n/a	'''
97	n/a	Start child process
98	n/a	'''
99	n/a	assert self._popen is None, 'cannot start a process twice'
100	n/a	assert self._parent_pid == os.getpid(), \
101	n/a	'can only start a process object created by current process'
102	n/a	assert not _current_process._config.get('daemon'), \
103	n/a	'daemonic processes are not allowed to have children'
104	n/a	_cleanup()
105	n/a	self._popen = self._Popen(self)
106	n/a	self._sentinel = self._popen.sentinel
107	n/a	_children.add(self)
108	n/a
109	n/a	def terminate(self):
110	n/a	'''
111	n/a	Terminate process; sends SIGTERM signal or uses TerminateProcess()
112	n/a	'''
113	n/a	self._popen.terminate()
114	n/a
115	n/a	def join(self, timeout=None):
116	n/a	'''
117	n/a	Wait until child process terminates
118	n/a	'''
119	n/a	assert self._parent_pid == os.getpid(), 'can only join a child process'
120	n/a	assert self._popen is not None, 'can only join a started process'
121	n/a	res = self._popen.wait(timeout)
122	n/a	if res is not None:
123	n/a	_children.discard(self)
124	n/a
125	n/a	def is_alive(self):
126	n/a	'''
127	n/a	Return whether process is alive
128	n/a	'''
129	n/a	if self is _current_process:
130	n/a	return True
131	n/a	assert self._parent_pid == os.getpid(), 'can only test a child process'
132	n/a	if self._popen is None:
133	n/a	return False
134	n/a	self._popen.poll()
135	n/a	return self._popen.returncode is None
136	n/a
137	n/a	@property
138	n/a	def name(self):
139	n/a	return self._name
140	n/a
141	n/a	@name.setter
142	n/a	def name(self, name):
143	n/a	assert isinstance(name, str), 'name must be a string'
144	n/a	self._name = name
145	n/a
146	n/a	@property
147	n/a	def daemon(self):
148	n/a	'''
149	n/a	Return whether process is a daemon
150	n/a	'''
151	n/a	return self._config.get('daemon', False)
152	n/a
153	n/a	@daemon.setter
154	n/a	def daemon(self, daemonic):
155	n/a	'''
156	n/a	Set whether process is a daemon
157	n/a	'''
158	n/a	assert self._popen is None, 'process has already started'
159	n/a	self._config['daemon'] = daemonic
160	n/a
161	n/a	@property
162	n/a	def authkey(self):
163	n/a	return self._config['authkey']
164	n/a
165	n/a	@authkey.setter
166	n/a	def authkey(self, authkey):
167	n/a	'''
168	n/a	Set authorization key of process
169	n/a	'''
170	n/a	self._config['authkey'] = AuthenticationString(authkey)
171	n/a
172	n/a	@property
173	n/a	def exitcode(self):
174	n/a	'''
175	n/a	Return exit code of process or `None` if it has yet to stop
176	n/a	'''
177	n/a	if self._popen is None:
178	n/a	return self._popen
179	n/a	return self._popen.poll()
180	n/a
181	n/a	@property
182	n/a	def ident(self):
183	n/a	'''
184	n/a	Return identifier (PID) of process or `None` if it has yet to start
185	n/a	'''
186	n/a	if self is _current_process:
187	n/a	return os.getpid()
188	n/a	else:
189	n/a	return self._popen and self._popen.pid
190	n/a
191	n/a	pid = ident
192	n/a
193	n/a	@property
194	n/a	def sentinel(self):
195	n/a	'''
196	n/a	Return a file descriptor (Unix) or handle (Windows) suitable for
197	n/a	waiting for process termination.
198	n/a	'''
199	n/a	try:
200	n/a	return self._sentinel
201	n/a	except AttributeError:
202	n/a	raise ValueError("process not started")
203	n/a
204	n/a	def __repr__(self):
205	n/a	if self is _current_process:
206	n/a	status = 'started'
207	n/a	elif self._parent_pid != os.getpid():
208	n/a	status = 'unknown'
209	n/a	elif self._popen is None:
210	n/a	status = 'initial'
211	n/a	else:
212	n/a	if self._popen.poll() is not None:
213	n/a	status = self.exitcode
214	n/a	else:
215	n/a	status = 'started'
216	n/a
217	n/a	if type(status) is int:
218	n/a	if status == 0:
219	n/a	status = 'stopped'
220	n/a	else:
221	n/a	status = 'stopped[%s]' % _exitcode_to_name.get(status, status)
222	n/a
223	n/a	return '<%s(%s, %s%s)>' % (type(self).__name__, self._name,
224	n/a	status, self.daemon and ' daemon' or '')
225	n/a
226	n/a	##
227	n/a
228	n/a	def _bootstrap(self):
229	n/a	from . import util, context
230	n/a	global _current_process, _process_counter, _children
231	n/a
232	n/a	try:
233	n/a	if self._start_method is not None:
234	n/a	context._force_start_method(self._start_method)
235	n/a	_process_counter = itertools.count(1)
236	n/a	_children = set()
237	n/a	util._close_stdin()
238	n/a	old_process = _current_process
239	n/a	_current_process = self
240	n/a	try:
241	n/a	util._finalizer_registry.clear()
242	n/a	util._run_after_forkers()
243	n/a	finally:
244	n/a	# delay finalization of the old process object until after
245	n/a	# _run_after_forkers() is executed
246	n/a	del old_process
247	n/a	util.info('child process calling self.run()')
248	n/a	try:
249	n/a	self.run()
250	n/a	exitcode = 0
251	n/a	finally:
252	n/a	util._exit_function()
253	n/a	except SystemExit as e:
254	n/a	if not e.args:
255	n/a	exitcode = 1
256	n/a	elif isinstance(e.args[0], int):
257	n/a	exitcode = e.args[0]
258	n/a	else:
259	n/a	sys.stderr.write(str(e.args[0]) + '\n')
260	n/a	exitcode = 1
261	n/a	except:
262	n/a	exitcode = 1
263	n/a	import traceback
264	n/a	sys.stderr.write('Process %s:\n' % self.name)
265	n/a	traceback.print_exc()
266	n/a	finally:
267	n/a	util.info('process exiting with exitcode %d' % exitcode)
268	n/a	sys.stdout.flush()
269	n/a	sys.stderr.flush()
270	n/a
271	n/a	return exitcode
272	n/a
273	n/a	#
274	n/a	# We subclass bytes to avoid accidental transmission of auth keys over network
275	n/a	#
276	n/a
277	n/a	class AuthenticationString(bytes):
278	n/a	def __reduce__(self):
279	n/a	from .context import get_spawning_popen
280	n/a	if get_spawning_popen() is None:
281	n/a	raise TypeError(
282	n/a	'Pickling an AuthenticationString object is '
283	n/a	'disallowed for security reasons'
284	n/a	)
285	n/a	return AuthenticationString, (bytes(self),)
286	n/a
287	n/a	#
288	n/a	# Create object representing the main process
289	n/a	#
290	n/a
291	n/a	class _MainProcess(BaseProcess):
292	n/a
293	n/a	def __init__(self):
294	n/a	self._identity = ()
295	n/a	self._name = 'MainProcess'
296	n/a	self._parent_pid = None
297	n/a	self._popen = None
298	n/a	self._config = {'authkey': AuthenticationString(os.urandom(32)),
299	n/a	'semprefix': '/mp'}
300	n/a	# Note that some versions of FreeBSD only allow named
301	n/a	# semaphores to have names of up to 14 characters. Therefore
302	n/a	# we choose a short prefix.
303	n/a	#
304	n/a	# On MacOSX in a sandbox it may be necessary to use a
305	n/a	# different prefix -- see #19478.
306	n/a	#
307	n/a	# Everything in self._config will be inherited by descendant
308	n/a	# processes.
309	n/a
310	n/a
311	n/a	_current_process = _MainProcess()
312	n/a	_process_counter = itertools.count(1)
313	n/a	_children = set()
314	n/a	del _MainProcess
315	n/a
316	n/a	#
317	n/a	# Give names to some return codes
318	n/a	#
319	n/a
320	n/a	_exitcode_to_name = {}
321	n/a
322	n/a	for name, signum in list(signal.__dict__.items()):
323	n/a	if name[:3]=='SIG' and '_' not in name:
324	n/a	_exitcode_to_name[-signum] = name
325	n/a
326	n/a	# For debug and leak testing
327	n/a	_dangling = WeakSet()