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#
# Module providing various facilities to other parts of the package
#
# multiprocessing/util.py
#
# Copyright (c) 2006-2008, R Oudkerk
# Licensed to PSF under a Contributor Agreement.
#
import os
import itertools
import sys
import weakref
import atexit
import threading # we want threading to install it's
# cleanup function before multiprocessing does
from subprocess import _args_from_interpreter_flags
from . import process
__all__ = [
'sub_debug', 'debug', 'info', 'sub_warning', 'get_logger',
'log_to_stderr', 'get_temp_dir', 'register_after_fork',
'is_exiting', 'Finalize', 'ForkAwareThreadLock', 'ForkAwareLocal',
'close_all_fds_except', '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
logging._acquireLock()
try:
if not _logger:
_logger = logging.getLogger(LOGGER_NAME)
_logger.propagate = 0
# 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 _remove_temp_dir(rmtree, tempdir):
rmtree(tempdir)
current_process = process.current_process()
# current_process() can be None if the finalizer is called
# late during Python finalization
if current_process is not None:
current_process._config['tempdir'] = None
def get_temp_dir():
# get name of a temp directory which will be automatically cleaned up
tempdir = process.current_process()._config.get('tempdir')
if tempdir is None:
import shutil, tempfile
tempdir = tempfile.mkdtemp(prefix='pymp-')
info('created temp directory %s', tempdir)
# keep a strong reference to shutil.rmtree(), since the finalizer
# can be called late during Python shutdown
Finalize(None, _remove_temp_dir, args=(shutil.rmtree, tempdir),
exitpriority=-100)
process.current_process()._config['tempdir'] = tempdir
return 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):
if (exitpriority is not None) and not isinstance(exitpriority,int):
raise TypeError(
"Exitpriority ({0!r}) must be None or int, not {1!s}".format(
exitpriority, type(exitpriority)))
if obj is not None:
self._weakref = weakref.ref(obj, self)
elif exitpriority is None:
raise ValueError("Without object, exitpriority cannot be None")
self._callback = callback
self._args = args
self._kwargs = kwargs or {}
self._key = (exitpriority, next(_finalizer_counter))
self._pid = os.getpid()
_finalizer_registry[self._key] = self
def __call__(self, wr=None,
# Need to bind these locally because the globals can have
# been cleared at shutdown
_finalizer_registry=_finalizer_registry,
sub_debug=sub_debug, getpid=os.getpid):
'''
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:
if self._pid != getpid():
sub_debug('finalizer ignored because different process')
res = None
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 '<%s object, dead>' % self.__class__.__name__
x = '<%s object, callback=%s' % (
self.__class__.__name__,
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 _finalizer_registry is None:
# This function may be called after this module's globals are
# destroyed. See the _exit_function function in this module for more
# notes.
return
if minpriority is None:
f = lambda p : p[0] is not None
else:
f = lambda p : p[0] is not None and p[0] >= minpriority
# Careful: _finalizer_registry may be mutated while this function
# is running (either by a GC run or by another thread).
# list(_finalizer_registry) should be atomic, while
# list(_finalizer_registry.items()) is not.
keys = [key for key in list(_finalizer_registry) if f(key)]
keys.sort(reverse=True)
for key in keys:
finalizer = _finalizer_registry.get(key)
# key may have been removed from the registry
if finalizer is not None:
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(info=info, debug=debug, _run_finalizers=_run_finalizers,
active_children=process.active_children,
current_process=process.current_process):
# We hold on to references to functions in the arglist due to the
# situation described below, where this function is called after this
# module's globals are destroyed.
global _exiting
if not _exiting:
_exiting = True
info('process shutting down')
debug('running all "atexit" finalizers with priority >= 0')
_run_finalizers(0)
if current_process() is not None:
# We check if the current process is None here because if
# it's None, any call to ``active_children()`` will raise
# an AttributeError (active_children winds up trying to
# get attributes from util._current_process). One
# situation where this can happen is if someone has
# manipulated sys.modules, causing this module to be
# garbage collected. The destructor for the module type
# then replaces all values in the module dict with None.
# For instance, after setuptools runs a test it replaces
# sys.modules with a copy created earlier. See issues
# #9775 and #15881. Also related: #4106, #9205, and
# #9207.
for p in active_children():
if p.daemon:
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._reset()
register_after_fork(self, ForkAwareThreadLock._reset)
def _reset(self):
self._lock = threading.Lock()
self.acquire = self._lock.acquire
self.release = self._lock.release
def __enter__(self):
return self._lock.__enter__()
def __exit__(self, *args):
return self._lock.__exit__(*args)
class ForkAwareLocal(threading.local):
def __init__(self):
register_after_fork(self, lambda obj : obj.__dict__.clear())
def __reduce__(self):
return type(self), ()
#
# Close fds except those specified
#
try:
MAXFD = os.sysconf("SC_OPEN_MAX")
except Exception:
MAXFD = 256
def close_all_fds_except(fds):
fds = list(fds) + [-1, MAXFD]
fds.sort()
assert fds[-1] == MAXFD, 'fd too large'
for i in range(len(fds) - 1):
os.closerange(fds[i]+1, fds[i+1])
#
# Close sys.stdin and replace stdin with os.devnull
#
def _close_stdin():
if sys.stdin is None:
return
try:
sys.stdin.close()
except (OSError, ValueError):
pass
try:
fd = os.open(os.devnull, os.O_RDONLY)
try:
sys.stdin = open(fd, closefd=False)
except:
os.close(fd)
raise
except (OSError, ValueError):
pass
#
# Flush standard streams, if any
#
def _flush_std_streams():
try:
sys.stdout.flush()
except (AttributeError, ValueError):
pass
try:
sys.stderr.flush()
except (AttributeError, ValueError):
pass
#
# Start a program with only specified fds kept open
#
def spawnv_passfds(path, args, passfds):
import _posixsubprocess
passfds = tuple(sorted(map(int, passfds)))
errpipe_read, errpipe_write = os.pipe()
try:
return _posixsubprocess.fork_exec(
args, [os.fsencode(path)], True, passfds, None, None,
-1, -1, -1, -1, -1, -1, errpipe_read, errpipe_write,
False, False, None)
finally:
os.close(errpipe_read)
os.close(errpipe_write)
def close_fds(*fds):
"""Close each file descriptor given as an argument"""
for fd in fds:
os.close(fd)
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