summaryrefslogtreecommitdiffstats
path: root/Lib/multiprocessing/util.py
blob: b13f5652b4f86bc02b0e462eef66fd8a60efa215 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
#
# Module providing various facilities to other parts of the package
#
# multiprocessing/util.py
#
# Copyright (c) 2006-2008, R Oudkerk --- see COPYING.txt
#

import itertools
import weakref
import atexit
import threading        # we want threading to install it's
                        # cleanup function before multiprocessing does

from multiprocessing.process import current_process, active_children

__all__ = [
    'sub_debug', 'debug', 'info', 'sub_warning', 'get_logger',
    'log_to_stderr', 'get_temp_dir', 'register_after_fork',
    'is_exiting', 'Finalize', 'ForkAwareThreadLock', 'ForkAwareLocal',
    'SUBDEBUG', 'SUBWARNING',
    ]

#
# Logging
#

NOTSET = 0
SUBDEBUG = 5
DEBUG = 10
INFO = 20
SUBWARNING = 25

LOGGER_NAME = 'multiprocessing'
DEFAULT_LOGGING_FORMAT = '[%(levelname)s/%(processName)s] %(message)s'

_logger = None
_log_to_stderr = False

def sub_debug(msg, *args):
    if _logger:
        _logger.log(SUBDEBUG, msg, *args)

def debug(msg, *args):
    if _logger:
        _logger.log(DEBUG, msg, *args)

def info(msg, *args):
    if _logger:
        _logger.log(INFO, msg, *args)

def sub_warning(msg, *args):
    if _logger:
        _logger.log(SUBWARNING, msg, *args)

def get_logger():
    '''
    Returns logger used by multiprocessing
    '''
    global _logger
    import logging, atexit

    logging._acquireLock()
    try:
        if not _logger:

            _logger = logging.getLogger(LOGGER_NAME)
            _logger.propagate = 0
            logging.addLevelName(SUBDEBUG, 'SUBDEBUG')
            logging.addLevelName(SUBWARNING, 'SUBWARNING')

            # XXX multiprocessing should cleanup before logging
            if hasattr(atexit, 'unregister'):
                atexit.unregister(_exit_function)
                atexit.register(_exit_function)
            else:
                atexit._exithandlers.remove((_exit_function, (), {}))
                atexit._exithandlers.append((_exit_function, (), {}))

    finally:
        logging._releaseLock()

    return _logger

def log_to_stderr(level=None):
    '''
    Turn on logging and add a handler which prints to stderr
    '''
    global _log_to_stderr
    import logging

    logger = get_logger()
    formatter = logging.Formatter(DEFAULT_LOGGING_FORMAT)
    handler = logging.StreamHandler()
    handler.setFormatter(formatter)
    logger.addHandler(handler)

    if level:
        logger.setLevel(level)
    _log_to_stderr = True
    return _logger

#
# Function returning a temp directory which will be removed on exit
#

def get_temp_dir():
    # get name of a temp directory which will be automatically cleaned up
    if current_process()._tempdir is None:
        import shutil, tempfile
        tempdir = tempfile.mkdtemp(prefix='pymp-')
        info('created temp directory %s', tempdir)
        Finalize(None, shutil.rmtree, args=[tempdir], exitpriority=-100)
        current_process()._tempdir = tempdir
    return current_process()._tempdir

#
# Support for reinitialization of objects when bootstrapping a child process
#

_afterfork_registry = weakref.WeakValueDictionary()
_afterfork_counter = itertools.count()

def _run_after_forkers():
    items = list(_afterfork_registry.items())
    items.sort()
    for (index, ident, func), obj in items:
        try:
            func(obj)
        except Exception as e:
            info('after forker raised exception %s', e)

def register_after_fork(obj, func):
    _afterfork_registry[(next(_afterfork_counter), id(obj), func)] = obj

#
# Finalization using weakrefs
#

_finalizer_registry = {}
_finalizer_counter = itertools.count()


class Finalize(object):
    '''
    Class which supports object finalization using weakrefs
    '''
    def __init__(self, obj, callback, args=(), kwargs=None, exitpriority=None):
        assert exitpriority is None or type(exitpriority) is int

        if obj is not None:
            self._weakref = weakref.ref(obj, self)
        else:
            assert exitpriority is not None

        self._callback = callback
        self._args = args
        self._kwargs = kwargs or {}
        self._key = (exitpriority, next(_finalizer_counter))

        _finalizer_registry[self._key] = self

    def __call__(self, wr=None):
        '''
        Run the callback unless it has already been called or cancelled
        '''
        try:
            del _finalizer_registry[self._key]
        except KeyError:
            sub_debug('finalizer no longer registered')
        else:
            sub_debug('finalizer calling %s with args %s and kwargs %s',
                     self._callback, self._args, self._kwargs)
            res = self._callback(*self._args, **self._kwargs)
            self._weakref = self._callback = self._args = \
                            self._kwargs = self._key = None
            return res

    def cancel(self):
        '''
        Cancel finalization of the object
        '''
        try:
            del _finalizer_registry[self._key]
        except KeyError:
            pass
        else:
            self._weakref = self._callback = self._args = \
                            self._kwargs = self._key = None

    def still_active(self):
        '''
        Return whether this finalizer is still waiting to invoke callback
        '''
        return self._key in _finalizer_registry

    def __repr__(self):
        try:
            obj = self._weakref()
        except (AttributeError, TypeError):
            obj = None

        if obj is None:
            return '<Finalize object, dead>'

        x = '<Finalize object, callback=%s' % \
            getattr(self._callback, '__name__', self._callback)
        if self._args:
            x += ', args=' + str(self._args)
        if self._kwargs:
            x += ', kwargs=' + str(self._kwargs)
        if self._key[0] is not None:
            x += ', exitprority=' + str(self._key[0])
        return x + '>'


def _run_finalizers(minpriority=None):
    '''
    Run all finalizers whose exit priority is not None and at least minpriority

    Finalizers with highest priority are called first; finalizers with
    the same priority will be called in reverse order of creation.
    '''
    if minpriority is None:
        f = lambda p : p[0][0] is not None
    else:
        f = lambda p : p[0][0] is not None and p[0][0] >= minpriority

    items = [x for x in list(_finalizer_registry.items()) if f(x)]
    items.sort(reverse=True)

    for key, finalizer in items:
        sub_debug('calling %s', finalizer)
        try:
            finalizer()
        except Exception:
            import traceback
            traceback.print_exc()

    if minpriority is None:
        _finalizer_registry.clear()

#
# Clean up on exit
#

def is_exiting():
    '''
    Returns true if the process is shutting down
    '''
    return _exiting or _exiting is None

_exiting = False

def _exit_function():
    global _exiting

    info('process shutting down')
    debug('running all "atexit" finalizers with priority >= 0')
    _run_finalizers(0)

    for p in active_children():
        if p._daemonic:
            info('calling terminate() for daemon %s', p.name)
            p._popen.terminate()

    for p in active_children():
        info('calling join() for process %s', p.name)
        p.join()

    debug('running the remaining "atexit" finalizers')
    _run_finalizers()

atexit.register(_exit_function)

#
# Some fork aware types
#

class ForkAwareThreadLock(object):
    def __init__(self):
        self._lock = threading.Lock()
        self.acquire = self._lock.acquire
        self.release = self._lock.release
        register_after_fork(self, ForkAwareThreadLock.__init__)

class ForkAwareLocal(threading.local):
    def __init__(self):
        register_after_fork(self, lambda obj : obj.__dict__.clear())
    def __reduce__(self):
        return type(self), ()