很抱歉,我不能用一个更简单的例子重现这个错误,而且我的代码太复杂了,无法发布。如果我在IPython shell而不是常规Python中运行程序,事情会很顺利。
我查阅了以前关于这个问题的一些笔记。它们都是由使用pool调用类函数中定义的函数引起的。但对我来说不是这样。
Exception in thread Thread-3:
Traceback (most recent call last):
File "/usr/lib64/python2.7/threading.py", line 552, in __bootstrap_inner
self.run()
File "/usr/lib64/python2.7/threading.py", line 505, in run
self.__target(*self.__args, **self.__kwargs)
File "/usr/lib64/python2.7/multiprocessing/pool.py", line 313, in _handle_tasks
put(task)
PicklingError: Can't pickle <type 'function'>: attribute lookup __builtin__.function failed
我很感激你的帮助。
更新:我pickle的函数是在模块的顶层定义的。尽管它调用了一个包含嵌套函数的函数。即,f()调用g()调用h(),其中有一个嵌套函数i(),我正在调用pool.apply_async(f)。F (), g(), h()都在顶层定义。我用这个模式尝试了一个更简单的例子,尽管它是有效的。
我会用悲怆。多处理,而不是多处理。感伤。Multiprocessing是Multiprocessing的一个分支,使用莳萝。Dill几乎可以序列化python中的任何东西,因此您可以并行地发送更多内容。正如类方法所需要的那样,pathos fork还能够直接使用多个参数函数。
>>> from pathos.multiprocessing import ProcessingPool as Pool
>>> p = Pool(4)
>>> class Test(object):
... def plus(self, x, y):
... return x+y
...
>>> t = Test()
>>> p.map(t.plus, x, y)
[4, 6, 8, 10]
>>>
>>> class Foo(object):
... @staticmethod
... def work(self, x):
... return x+1
...
>>> f = Foo()
>>> p.apipe(f.work, f, 100)
<processing.pool.ApplyResult object at 0x10504f8d0>
>>> res = _
>>> res.get()
101
在这里获得感伤(如果你喜欢,莳萝):
https://github.com/uqfoundation
基于@rocksportrocker解决方案,
在发送和RECVing结果时使用dill是有意义的。
import dill
import itertools
def run_dill_encoded(payload):
fun, args = dill.loads(payload)
res = fun(*args)
res = dill.dumps(res)
return res
def dill_map_async(pool, fun, args_list,
as_tuple=True,
**kw):
if as_tuple:
args_list = ((x,) for x in args_list)
it = itertools.izip(
itertools.cycle([fun]),
args_list)
it = itertools.imap(dill.dumps, it)
return pool.map_async(run_dill_encoded, it, **kw)
if __name__ == '__main__':
import multiprocessing as mp
import sys,os
p = mp.Pool(4)
res = dill_map_async(p, lambda x:[sys.stdout.write('%s\n'%os.getpid()),x][-1],
[lambda x:x+1]*10,)
res = res.get(timeout=100)
res = map(dill.loads,res)
print(res)
正如@penky Suresh在这个回答中建议的那样,不要使用内置关键字。
显然,args是处理多处理时的内置关键字
class TTS:
def __init__(self):
pass
def process_and_render_items(self):
multiprocessing_args = [{"a": "b", "c": "d"}, {"e": "f", "g": "h"}]
with ProcessPoolExecutor(max_workers=10) as executor:
# Using args here is fine.
future_processes = {
executor.submit(TTS.process_and_render_item, args)
for args in multiprocessing_args
}
for future in as_completed(future_processes):
try:
data = future.result()
except Exception as exc:
print(f"Generated an exception: {exc}")
else:
print(f"Generated data for comment process: {future}")
# Dont use 'args' here. It seems to be a built-in keyword.
# Changing 'args' to 'arg' worked for me.
def process_and_render_item(arg):
print(arg)
# This will print {"a": "b", "c": "d"} for the first process
# and {"e": "f", "g": "h"} for the second process.
PS:制表符/空格可能有点不对。
这里列出了一些可以腌制的东西。特别是,函数只有在模块的顶层定义时才可pickle。
这段代码:
import multiprocessing as mp
class Foo():
@staticmethod
def work(self):
pass
if __name__ == '__main__':
pool = mp.Pool()
foo = Foo()
pool.apply_async(foo.work)
pool.close()
pool.join()
产生一个错误几乎相同的一个你张贴:
Exception in thread Thread-2:
Traceback (most recent call last):
File "/usr/lib/python2.7/threading.py", line 552, in __bootstrap_inner
self.run()
File "/usr/lib/python2.7/threading.py", line 505, in run
self.__target(*self.__args, **self.__kwargs)
File "/usr/lib/python2.7/multiprocessing/pool.py", line 315, in _handle_tasks
put(task)
PicklingError: Can't pickle <type 'function'>: attribute lookup __builtin__.function failed
问题是池方法都使用mp。SimpleQueue将任务传递给工作进程。所有经过mp的东西。SimpleQueue必须是可选的,而foo。工作是不可pickle的,因为它没有在模块的顶层定义。
可以通过在顶层定义一个调用foo.work()的函数来修复:
def work(foo):
foo.work()
pool.apply_async(work,args=(foo,))
注意,foo是可选的,因为foo是在顶层定义的。__dict__是可腌制的。