class Pool(object):
'''
Class which supports an async version of applying functions to arguments.
'''
_wrap_exception = True
def Process(self, *args, **kwds):
return self._ctx.Process(*args, **kwds)
def __init__(self, processes=None, initializer=None, initargs=(),
maxtasksperchild=None, context=None):
self._ctx = context or get_context()
#self._setup_queues()
self._taskqueue = queue.Queue()
self._cache = {}
self._state = RUN
self._maxtasksperchild = maxtasksperchild
self._initializer = initializer
self._initargs = initargs
if processes is not None and processes < 1:
raise ValueError("Number of processes must be at least 1")
if processes is not None:
if self._initargs:
self._executor = FunctionExecutor(workers=processes, **self._initargs)
else:
self._executor = FunctionExecutor(workers=processes)
self._processes = processes
else:
if self._initargs:
self._executor = FunctionExecutor(**self._initargs)
else:
self._executor = FunctionExecutor()
self._processes = self._executor.invoker.workers
if initializer is not None and not callable(initializer):
raise TypeError('initializer must be a callable')
self._pool = []
#self._repopulate_pool()
# self._worker_handler = threading.Thread(
# target=Pool._handle_workers,
# args=(self, )
# )
# 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._worker_handler, self._task_handler,
# self._result_handler, self._cache),
# exitpriority=15
# )
def _join_exited_workers(self):
"""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(self._pool))):
worker = self._pool[i]
if worker.exitcode is not None:
# worker exited
util.debug('cleaning up worker %d' % i)
worker.join()
cleaned = True
del self._pool[i]
return cleaned
def _repopulate_pool(self):
"""Bring the number of pool processes up to the specified number,
for use after reaping workers which have exited.
"""
for i in range(self._processes - len(self._pool)):
w = self.Process(target=worker,
args=(self._inqueue, self._outqueue,
self._initializer,
self._initargs, self._maxtasksperchild,
self._wrap_exception)
)
self._pool.append(w)
w.name = w.name.replace('Process', 'PoolWorker')
w.daemon = True
w.start()
util.debug('added worker')
def _maintain_pool(self):
"""Clean up any exited workers and start replacements for them.
"""
if self._join_exited_workers():
self._repopulate_pool()
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 apply(self, func, args=(), kwds={}):
'''
Equivalent of `func(*args, **kwds)`.
'''
assert self._state == RUN
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()`.
'''
if self._state != RUN:
raise ValueError("Pool not running")
if chunksize == 1:
result = IMapIterator(self._cache)
self._taskqueue.put(
(
self._guarded_task_generation(result._job, func, iterable),
result._set_length
))
return result
else:
assert chunksize > 1
task_batches = Pool._get_tasks(func, iterable, chunksize)
result = IMapIterator(self._cache)
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.
'''
if self._state != RUN:
raise ValueError("Pool not running")
if chunksize == 1:
result = IMapUnorderedIterator(self._cache)
self._taskqueue.put(
(
self._guarded_task_generation(result._job, func, iterable),
result._set_length
))
return result
else:
assert chunksize > 1
task_batches = Pool._get_tasks(func, iterable, chunksize)
result = IMapUnorderedIterator(self._cache)
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.
'''
if self._state != RUN:
raise ValueError("Pool not running")
futures = self._executor.call_async(func, [*args, *kwds])
result = ApplyResult(self._executor, [futures], callback, error_callback)
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.
'''
if self._state != RUN:
raise ValueError("Pool not running")
if not hasattr(iterable, '__len__'):
iterable = list(iterable)
futures = self._executor.map(func, iterable)
result = MapResult(self._executor, futures, callback, error_callback)
return result
@staticmethod
def _handle_workers(pool):
thread = threading.current_thread()
# Keep maintaining workers until the cache gets drained, unless the pool
# is terminated.
while thread._state == RUN or (pool._cache and thread._state != TERMINATE):
pool._maintain_pool()
time.sleep(0.1)
# send sentinel to stop workers
pool._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:
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:
assert thread._state == 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
def terminate(self):
util.debug('terminating pool')
self._state = TERMINATE
#self._worker_handler._state = TERMINATE
#self._terminate()
self._executor.clean()
def join(self):
util.debug('joining pool')
assert self._state in (CLOSE, TERMINATE)
#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')
while task_handler.is_alive() and inqueue._reader.poll():
inqueue._reader.recv()
time.sleep(0)
@classmethod
def _terminate_pool(cls, taskqueue, inqueue, outqueue, pool,
worker_handler, task_handler, result_handler, cache):
# this is guaranteed to only be called once
util.debug('finalizing pool')
worker_handler._state = TERMINATE
task_handler._state = TERMINATE
util.debug('helping task handler/workers to finish')
cls._help_stuff_finish(inqueue, task_handler, len(pool))
assert result_handler.is_alive() or len(cache) == 0
result_handler._state = TERMINATE
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):
return self
def __exit__(self, exc_type, exc_val, exc_tb):
self.terminate()
"""
Simple Cloudbutton example using the map method
of the raw API.
In this example the map() method will launch one
map function for each entry in 'iterdata'. Finally
it will print the results for each invocation with
pw.get_result()
"""
from cloudbutton.engine.executor import FunctionExecutor
def my_map_function(id, x):
print("I'm activation number {}".format(id))
return x + 7
if __name__ == "__main__":
iterdata = [1, 2, 3, 4]
cb_exc = FunctionExecutor()
cb_exc.map(my_map_function, iterdata)
print(cb_exc.get_result())
cb_exc.clean()