Staging
v0.8.1
v0.8.1
https://github.com/python/cpython
Revision dc8ce8ead182de46584cc1ed8a8c51d48240cbd5 authored by Miss Islington (bot) on 29 June 2020, 18:12:50 UTC, committed by GitHub on 29 June 2020, 18:12:50 UTC
The __hash__() methods of classes IPv4Interface and IPv6Interface had issue of generating constant hash values of 32 and 128 respectively causing hash collisions. The fix uses the hash() function to generate hash values for the objects instead of XOR operation (cherry picked from commit b30ee26e366bf509b7538d79bfec6c6d38d53f28) Co-authored-by: Ravi Teja P <rvteja92@gmail.com>
1 parent 7731139
Tip revision: dc8ce8ead182de46584cc1ed8a8c51d48240cbd5 authored by Miss Islington (bot) on 29 June 2020, 18:12:50 UTC
bpo-41004: Resolve hash collisions for IPv4Interface and IPv6Interface (GH-21033)
bpo-41004: Resolve hash collisions for IPv4Interface and IPv6Interface (GH-21033)
Tip revision: dc8ce8e
pool.py
#
# Module providing the `Pool` class for managing a process pool
#
# multiprocessing/pool.py
#
# Copyright (c) 2006-2008, R Oudkerk
# Licensed to PSF under a Contributor Agreement.
#
__all__ = ['Pool', 'ThreadPool']
#
# Imports
#
import collections
import itertools
import os
import queue
import threading
import time
import traceback
import warnings
from queue import Empty
# If threading is available then ThreadPool should be provided. Therefore
# we avoid top-level imports which are liable to fail on some systems.
from . import util
from . import get_context, TimeoutError
from .connection import wait
#
# Constants representing the state of a pool
#
INIT = "INIT"
RUN = "RUN"
CLOSE = "CLOSE"
TERMINATE = "TERMINATE"
#
# Miscellaneous
#
job_counter = itertools.count()
def mapstar(args):
return list(map(*args))
def starmapstar(args):
return list(itertools.starmap(args[0], args[1]))
#
# Hack to embed stringification of remote traceback in local traceback
#
class RemoteTraceback(Exception):
def __init__(self, tb):
self.tb = tb
def __str__(self):
return self.tb
class ExceptionWithTraceback:
def __init__(self, exc, tb):
tb = traceback.format_exception(type(exc), exc, tb)
tb = ''.join(tb)
self.exc = exc
self.tb = '\n"""\n%s"""' % tb
def __reduce__(self):
return rebuild_exc, (self.exc, self.tb)
def rebuild_exc(exc, tb):
exc.__cause__ = RemoteTraceback(tb)
return exc
#
# Code run by worker processes
#
class MaybeEncodingError(Exception):
"""Wraps possible unpickleable errors, so they can be
safely sent through the socket."""
def __init__(self, exc, value):
self.exc = repr(exc)
self.value = repr(value)
super(MaybeEncodingError, self).__init__(self.exc, self.value)
def __str__(self):
return "Error sending result: '%s'. Reason: '%s'" % (self.value,
self.exc)
def __repr__(self):
return "<%s: %s>" % (self.__class__.__name__, self)
def worker(inqueue, outqueue, initializer=None, initargs=(), maxtasks=None,
wrap_exception=False):
if (maxtasks is not None) and not (isinstance(maxtasks, int)
and maxtasks >= 1):
raise AssertionError("Maxtasks {!r} is not valid".format(maxtasks))
put = outqueue.put
get = inqueue.get
if hasattr(inqueue, '_writer'):
inqueue._writer.close()
outqueue._reader.close()
if initializer is not None:
initializer(*initargs)
completed = 0
while maxtasks is None or (maxtasks and completed < maxtasks):
try:
task = get()
except (EOFError, OSError):
util.debug('worker got EOFError or OSError -- exiting')
break
if task is None:
util.debug('worker got sentinel -- exiting')
break
job, i, func, args, kwds = task
try:
result = (True, func(*args, **kwds))
except Exception as e:
if wrap_exception and func is not _helper_reraises_exception:
e = ExceptionWithTraceback(e, e.__traceback__)
result = (False, e)
try:
put((job, i, result))
except Exception as e:
wrapped = MaybeEncodingError(e, result[1])
util.debug("Possible encoding error while sending result: %s" % (
wrapped))
put((job, i, (False, wrapped)))
task = job = result = func = args = kwds = None
completed += 1
util.debug('worker exiting after %d tasks' % completed)
def _helper_reraises_exception(ex):
'Pickle-able helper function for use by _guarded_task_generation.'
raise ex
#
# Class representing a process pool
#
class _PoolCache(dict):
"""
Class that implements a cache for the Pool class that will notify
the pool management threads every time the cache is emptied. The
notification is done by the use of a queue that is provided when
instantiating the cache.
"""
def __init__(self, /, *args, notifier=None, **kwds):
self.notifier = notifier
super().__init__(*args, **kwds)
def __delitem__(self, item):
super().__delitem__(item)
# Notify that the cache is empty. This is important because the
# pool keeps maintaining workers until the cache gets drained. This
# eliminates a race condition in which a task is finished after the
# the pool's _handle_workers method has enter another iteration of the
# loop. In this situation, the only event that can wake up the pool
# is the cache to be emptied (no more tasks available).
if not self:
self.notifier.put(None)
class Pool(object):
'''
Class which supports an async version of applying functions to arguments.
'''
_wrap_exception = True
@staticmethod
def Process(ctx, *args, **kwds):
return ctx.Process(*args, **kwds)
def __init__(self, processes=None, initializer=None, initargs=(),
maxtasksperchild=None, context=None):
# Attributes initialized early to make sure that they exist in
# __del__() if __init__() raises an exception
self._pool = []
self._state = INIT
self._ctx = context or get_context()
self._setup_queues()
self._taskqueue = queue.SimpleQueue()
# The _change_notifier queue exist to wake up self._handle_workers()
# when the cache (self._cache) is empty or when there is a change in
# the _state variable of the thread that runs _handle_workers.
self._change_notifier = self._ctx.SimpleQueue()
self._cache = _PoolCache(notifier=self._change_notifier)
self._maxtasksperchild = maxtasksperchild
self._initializer = initializer
self._initargs = initargs
if processes is None:
processes = os.cpu_count() or 1
if processes < 1:
raise ValueError("Number of processes must be at least 1")
if initializer is not None and not callable(initializer):
raise TypeError('initializer must be a callable')
self._processes = processes
try:
self._repopulate_pool()
except Exception:
for p in self._pool:
if p.exitcode is None:
p.terminate()
for p in self._pool:
p.join()
raise
sentinels = self._get_sentinels()
self._worker_handler = threading.Thread(
target=Pool._handle_workers,
args=(self._cache, self._taskqueue, self._ctx, self.Process,
self._processes, self._pool, self._inqueue, self._outqueue,
self._initializer, self._initargs, self._maxtasksperchild,
self._wrap_exception, sentinels, self._change_notifier)
)
self._worker_handler.daemon = True
self._worker_handler._state = RUN
self._worker_handler.start()
self._task_handler = threading.Thread(
target=Pool._handle_tasks,
args=(self._taskqueue, self._quick_put, self._outqueue,
self._pool, self._cache)
)
self._task_handler.daemon = True
self._task_handler._state = RUN
self._task_handler.start()
self._result_handler = threading.Thread(
target=Pool._handle_results,
args=(self._outqueue, self._quick_get, self._cache)
)
self._result_handler.daemon = True
self._result_handler._state = RUN
self._result_handler.start()
self._terminate = util.Finalize(
self, self._terminate_pool,
args=(self._taskqueue, self._inqueue, self._outqueue, self._pool,
self._change_notifier, self._worker_handler, self._task_handler,
self._result_handler, self._cache),
exitpriority=15
)
self._state = RUN
# Copy globals as function locals to make sure that they are available
# during Python shutdown when the Pool is destroyed.
def __del__(self, _warn=warnings.warn, RUN=RUN):
if self._state == RUN:
_warn(f"unclosed running multiprocessing pool {self!r}",
ResourceWarning, source=self)
if getattr(self, '_change_notifier', None) is not None:
self._change_notifier.put(None)
def __repr__(self):
cls = self.__class__
return (f'<{cls.__module__}.{cls.__qualname__} '
f'state={self._state} '
f'pool_size={len(self._pool)}>')
def _get_sentinels(self):
task_queue_sentinels = [self._outqueue._reader]
self_notifier_sentinels = [self._change_notifier._reader]
return [*task_queue_sentinels, *self_notifier_sentinels]
@staticmethod
def _get_worker_sentinels(workers):
return [worker.sentinel for worker in
workers if hasattr(worker, "sentinel")]
@staticmethod
def _join_exited_workers(pool):
"""Cleanup after any worker processes which have exited due to reaching
their specified lifetime. Returns True if any workers were cleaned up.
"""
cleaned = False
for i in reversed(range(len(pool))):
worker = pool[i]
if worker.exitcode is not None:
# worker exited
util.debug('cleaning up worker %d' % i)
worker.join()
cleaned = True
del pool[i]
return cleaned
def _repopulate_pool(self):
return self._repopulate_pool_static(self._ctx, self.Process,
self._processes,
self._pool, self._inqueue,
self._outqueue, self._initializer,
self._initargs,
self._maxtasksperchild,
self._wrap_exception)
@staticmethod
def _repopulate_pool_static(ctx, Process, processes, pool, inqueue,
outqueue, initializer, initargs,
maxtasksperchild, wrap_exception):
"""Bring the number of pool processes up to the specified number,
for use after reaping workers which have exited.
"""
for i in range(processes - len(pool)):
w = Process(ctx, target=worker,
args=(inqueue, outqueue,
initializer,
initargs, maxtasksperchild,
wrap_exception))
w.name = w.name.replace('Process', 'PoolWorker')
w.daemon = True
w.start()
pool.append(w)
util.debug('added worker')
@staticmethod
def _maintain_pool(ctx, Process, processes, pool, inqueue, outqueue,
initializer, initargs, maxtasksperchild,
wrap_exception):
"""Clean up any exited workers and start replacements for them.
"""
if Pool._join_exited_workers(pool):
Pool._repopulate_pool_static(ctx, Process, processes, pool,
inqueue, outqueue, initializer,
initargs, maxtasksperchild,
wrap_exception)
def _setup_queues(self):
self._inqueue = self._ctx.SimpleQueue()
self._outqueue = self._ctx.SimpleQueue()
self._quick_put = self._inqueue._writer.send
self._quick_get = self._outqueue._reader.recv
def _check_running(self):
if self._state != RUN:
raise ValueError("Pool not running")
def apply(self, func, args=(), kwds={}):
'''
Equivalent of `func(*args, **kwds)`.
Pool must be running.
'''
return self.apply_async(func, args, kwds).get()
def map(self, func, iterable, chunksize=None):
'''
Apply `func` to each element in `iterable`, collecting the results
in a list that is returned.
'''
return self._map_async(func, iterable, mapstar, chunksize).get()
def starmap(self, func, iterable, chunksize=None):
'''
Like `map()` method but the elements of the `iterable` are expected to
be iterables as well and will be unpacked as arguments. Hence
`func` and (a, b) becomes func(a, b).
'''
return self._map_async(func, iterable, starmapstar, chunksize).get()
def starmap_async(self, func, iterable, chunksize=None, callback=None,
error_callback=None):
'''
Asynchronous version of `starmap()` method.
'''
return self._map_async(func, iterable, starmapstar, chunksize,
callback, error_callback)
def _guarded_task_generation(self, result_job, func, iterable):
'''Provides a generator of tasks for imap and imap_unordered with
appropriate handling for iterables which throw exceptions during
iteration.'''
try:
i = -1
for i, x in enumerate(iterable):
yield (result_job, i, func, (x,), {})
except Exception as e:
yield (result_job, i+1, _helper_reraises_exception, (e,), {})
def imap(self, func, iterable, chunksize=1):
'''
Equivalent of `map()` -- can be MUCH slower than `Pool.map()`.
'''
self._check_running()
if chunksize == 1:
result = IMapIterator(self)
self._taskqueue.put(
(
self._guarded_task_generation(result._job, func, iterable),
result._set_length
))
return result
else:
if chunksize < 1:
raise ValueError(
"Chunksize must be 1+, not {0:n}".format(
chunksize))
task_batches = Pool._get_tasks(func, iterable, chunksize)
result = IMapIterator(self)
self._taskqueue.put(
(
self._guarded_task_generation(result._job,
mapstar,
task_batches),
result._set_length
))
return (item for chunk in result for item in chunk)
def imap_unordered(self, func, iterable, chunksize=1):
'''
Like `imap()` method but ordering of results is arbitrary.
'''
self._check_running()
if chunksize == 1:
result = IMapUnorderedIterator(self)
self._taskqueue.put(
(
self._guarded_task_generation(result._job, func, iterable),
result._set_length
))
return result
else:
if chunksize < 1:
raise ValueError(
"Chunksize must be 1+, not {0!r}".format(chunksize))
task_batches = Pool._get_tasks(func, iterable, chunksize)
result = IMapUnorderedIterator(self)
self._taskqueue.put(
(
self._guarded_task_generation(result._job,
mapstar,
task_batches),
result._set_length
))
return (item for chunk in result for item in chunk)
def apply_async(self, func, args=(), kwds={}, callback=None,
error_callback=None):
'''
Asynchronous version of `apply()` method.
'''
self._check_running()
result = ApplyResult(self, callback, error_callback)
self._taskqueue.put(([(result._job, 0, func, args, kwds)], None))
return result
def map_async(self, func, iterable, chunksize=None, callback=None,
error_callback=None):
'''
Asynchronous version of `map()` method.
'''
return self._map_async(func, iterable, mapstar, chunksize, callback,
error_callback)
def _map_async(self, func, iterable, mapper, chunksize=None, callback=None,
error_callback=None):
'''
Helper function to implement map, starmap and their async counterparts.
'''
self._check_running()
if not hasattr(iterable, '__len__'):
iterable = list(iterable)
if chunksize is None:
chunksize, extra = divmod(len(iterable), len(self._pool) * 4)
if extra:
chunksize += 1
if len(iterable) == 0:
chunksize = 0
task_batches = Pool._get_tasks(func, iterable, chunksize)
result = MapResult(self, chunksize, len(iterable), callback,
error_callback=error_callback)
self._taskqueue.put(
(
self._guarded_task_generation(result._job,
mapper,
task_batches),
None
)
)
return result
@staticmethod
def _wait_for_updates(sentinels, change_notifier, timeout=None):
wait(sentinels, timeout=timeout)
while not change_notifier.empty():
change_notifier.get()
@classmethod
def _handle_workers(cls, cache, taskqueue, ctx, Process, processes,
pool, inqueue, outqueue, initializer, initargs,
maxtasksperchild, wrap_exception, sentinels,
change_notifier):
thread = threading.current_thread()
# Keep maintaining workers until the cache gets drained, unless the pool
# is terminated.
while thread._state == RUN or (cache and thread._state != TERMINATE):
cls._maintain_pool(ctx, Process, processes, pool, inqueue,
outqueue, initializer, initargs,
maxtasksperchild, wrap_exception)
current_sentinels = [*cls._get_worker_sentinels(pool), *sentinels]
cls._wait_for_updates(current_sentinels, change_notifier)
# send sentinel to stop workers
taskqueue.put(None)
util.debug('worker handler exiting')
@staticmethod
def _handle_tasks(taskqueue, put, outqueue, pool, cache):
thread = threading.current_thread()
for taskseq, set_length in iter(taskqueue.get, None):
task = None
try:
# iterating taskseq cannot fail
for task in taskseq:
if thread._state != RUN:
util.debug('task handler found thread._state != RUN')
break
try:
put(task)
except Exception as e:
job, idx = task[:2]
try:
cache[job]._set(idx, (False, e))
except KeyError:
pass
else:
if set_length:
util.debug('doing set_length()')
idx = task[1] if task else -1
set_length(idx + 1)
continue
break
finally:
task = taskseq = job = None
else:
util.debug('task handler got sentinel')
try:
# tell result handler to finish when cache is empty
util.debug('task handler sending sentinel to result handler')
outqueue.put(None)
# tell workers there is no more work
util.debug('task handler sending sentinel to workers')
for p in pool:
put(None)
except OSError:
util.debug('task handler got OSError when sending sentinels')
util.debug('task handler exiting')
@staticmethod
def _handle_results(outqueue, get, cache):
thread = threading.current_thread()
while 1:
try:
task = get()
except (OSError, EOFError):
util.debug('result handler got EOFError/OSError -- exiting')
return
if thread._state != RUN:
assert thread._state == TERMINATE, "Thread not in TERMINATE"
util.debug('result handler found thread._state=TERMINATE')
break
if task is None:
util.debug('result handler got sentinel')
break
job, i, obj = task
try:
cache[job]._set(i, obj)
except KeyError:
pass
task = job = obj = None
while cache and thread._state != TERMINATE:
try:
task = get()
except (OSError, EOFError):
util.debug('result handler got EOFError/OSError -- exiting')
return
if task is None:
util.debug('result handler ignoring extra sentinel')
continue
job, i, obj = task
try:
cache[job]._set(i, obj)
except KeyError:
pass
task = job = obj = None
if hasattr(outqueue, '_reader'):
util.debug('ensuring that outqueue is not full')
# If we don't make room available in outqueue then
# attempts to add the sentinel (None) to outqueue may
# block. There is guaranteed to be no more than 2 sentinels.
try:
for i in range(10):
if not outqueue._reader.poll():
break
get()
except (OSError, EOFError):
pass
util.debug('result handler exiting: len(cache)=%s, thread._state=%s',
len(cache), thread._state)
@staticmethod
def _get_tasks(func, it, size):
it = iter(it)
while 1:
x = tuple(itertools.islice(it, size))
if not x:
return
yield (func, x)
def __reduce__(self):
raise NotImplementedError(
'pool objects cannot be passed between processes or pickled'
)
def close(self):
util.debug('closing pool')
if self._state == RUN:
self._state = CLOSE
self._worker_handler._state = CLOSE
self._change_notifier.put(None)
def terminate(self):
util.debug('terminating pool')
self._state = TERMINATE
self._terminate()
def join(self):
util.debug('joining pool')
if self._state == RUN:
raise ValueError("Pool is still running")
elif self._state not in (CLOSE, TERMINATE):
raise ValueError("In unknown state")
self._worker_handler.join()
self._task_handler.join()
self._result_handler.join()
for p in self._pool:
p.join()
@staticmethod
def _help_stuff_finish(inqueue, task_handler, size):
# task_handler may be blocked trying to put items on inqueue
util.debug('removing tasks from inqueue until task handler finished')
inqueue._rlock.acquire()
while task_handler.is_alive() and inqueue._reader.poll():
inqueue._reader.recv()
time.sleep(0)
@classmethod
def _terminate_pool(cls, taskqueue, inqueue, outqueue, pool, change_notifier,
worker_handler, task_handler, result_handler, cache):
# this is guaranteed to only be called once
util.debug('finalizing pool')
# Notify that the worker_handler state has been changed so the
# _handle_workers loop can be unblocked (and exited) in order to
# send the finalization sentinel all the workers.
worker_handler._state = TERMINATE
change_notifier.put(None)
task_handler._state = TERMINATE
util.debug('helping task handler/workers to finish')
cls._help_stuff_finish(inqueue, task_handler, len(pool))
if (not result_handler.is_alive()) and (len(cache) != 0):
raise AssertionError(
"Cannot have cache with result_hander not alive")
result_handler._state = TERMINATE
change_notifier.put(None)
outqueue.put(None) # sentinel
# We must wait for the worker handler to exit before terminating
# workers because we don't want workers to be restarted behind our back.
util.debug('joining worker handler')
if threading.current_thread() is not worker_handler:
worker_handler.join()
# Terminate workers which haven't already finished.
if pool and hasattr(pool[0], 'terminate'):
util.debug('terminating workers')
for p in pool:
if p.exitcode is None:
p.terminate()
util.debug('joining task handler')
if threading.current_thread() is not task_handler:
task_handler.join()
util.debug('joining result handler')
if threading.current_thread() is not result_handler:
result_handler.join()
if pool and hasattr(pool[0], 'terminate'):
util.debug('joining pool workers')
for p in pool:
if p.is_alive():
# worker has not yet exited
util.debug('cleaning up worker %d' % p.pid)
p.join()
def __enter__(self):
self._check_running()
return self
def __exit__(self, exc_type, exc_val, exc_tb):
self.terminate()
#
# Class whose instances are returned by `Pool.apply_async()`
#
class ApplyResult(object):
def __init__(self, pool, callback, error_callback):
self._pool = pool
self._event = threading.Event()
self._job = next(job_counter)
self._cache = pool._cache
self._callback = callback
self._error_callback = error_callback
self._cache[self._job] = self
def ready(self):
return self._event.is_set()
def successful(self):
if not self.ready():
raise ValueError("{0!r} not ready".format(self))
return self._success
def wait(self, timeout=None):
self._event.wait(timeout)
def get(self, timeout=None):
self.wait(timeout)
if not self.ready():
raise TimeoutError
if self._success:
return self._value
else:
raise self._value
def _set(self, i, obj):
self._success, self._value = obj
if self._callback and self._success:
self._callback(self._value)
if self._error_callback and not self._success:
self._error_callback(self._value)
self._event.set()
del self._cache[self._job]
self._pool = None
AsyncResult = ApplyResult # create alias -- see #17805
#
# Class whose instances are returned by `Pool.map_async()`
#
class MapResult(ApplyResult):
def __init__(self, pool, chunksize, length, callback, error_callback):
ApplyResult.__init__(self, pool, callback,
error_callback=error_callback)
self._success = True
self._value = [None] * length
self._chunksize = chunksize
if chunksize <= 0:
self._number_left = 0
self._event.set()
del self._cache[self._job]
else:
self._number_left = length//chunksize + bool(length % chunksize)
def _set(self, i, success_result):
self._number_left -= 1
success, result = success_result
if success and self._success:
self._value[i*self._chunksize:(i+1)*self._chunksize] = result
if self._number_left == 0:
if self._callback:
self._callback(self._value)
del self._cache[self._job]
self._event.set()
self._pool = None
else:
if not success and self._success:
# only store first exception
self._success = False
self._value = result
if self._number_left == 0:
# only consider the result ready once all jobs are done
if self._error_callback:
self._error_callback(self._value)
del self._cache[self._job]
self._event.set()
self._pool = None
#
# Class whose instances are returned by `Pool.imap()`
#
class IMapIterator(object):
def __init__(self, pool):
self._pool = pool
self._cond = threading.Condition(threading.Lock())
self._job = next(job_counter)
self._cache = pool._cache
self._items = collections.deque()
self._index = 0
self._length = None
self._unsorted = {}
self._cache[self._job] = self
def __iter__(self):
return self
def next(self, timeout=None):
with self._cond:
try:
item = self._items.popleft()
except IndexError:
if self._index == self._length:
self._pool = None
raise StopIteration from None
self._cond.wait(timeout)
try:
item = self._items.popleft()
except IndexError:
if self._index == self._length:
self._pool = None
raise StopIteration from None
raise TimeoutError from None
success, value = item
if success:
return value
raise value
__next__ = next # XXX
def _set(self, i, obj):
with self._cond:
if self._index == i:
self._items.append(obj)
self._index += 1
while self._index in self._unsorted:
obj = self._unsorted.pop(self._index)
self._items.append(obj)
self._index += 1
self._cond.notify()
else:
self._unsorted[i] = obj
if self._index == self._length:
del self._cache[self._job]
self._pool = None
def _set_length(self, length):
with self._cond:
self._length = length
if self._index == self._length:
self._cond.notify()
del self._cache[self._job]
self._pool = None
#
# Class whose instances are returned by `Pool.imap_unordered()`
#
class IMapUnorderedIterator(IMapIterator):
def _set(self, i, obj):
with self._cond:
self._items.append(obj)
self._index += 1
self._cond.notify()
if self._index == self._length:
del self._cache[self._job]
self._pool = None
#
#
#
class ThreadPool(Pool):
_wrap_exception = False
@staticmethod
def Process(ctx, *args, **kwds):
from .dummy import Process
return Process(*args, **kwds)
def __init__(self, processes=None, initializer=None, initargs=()):
Pool.__init__(self, processes, initializer, initargs)
def _setup_queues(self):
self._inqueue = queue.SimpleQueue()
self._outqueue = queue.SimpleQueue()
self._quick_put = self._inqueue.put
self._quick_get = self._outqueue.get
def _get_sentinels(self):
return [self._change_notifier._reader]
@staticmethod
def _get_worker_sentinels(workers):
return []
@staticmethod
def _help_stuff_finish(inqueue, task_handler, size):
# drain inqueue, and put sentinels at its head to make workers finish
try:
while True:
inqueue.get(block=False)
except queue.Empty:
pass
for i in range(size):
inqueue.put(None)
def _wait_for_updates(self, sentinels, change_notifier, timeout):
time.sleep(timeout)
Computing file changes ...