“TypeError: 'list' 和 'int' 的實例之間不支持'<='”在使用 multiprocessing.Pool() 時發生

Question

from multiprocessing import Pool

def f(x,y):
    return x*y

with Pool(4) as p:
    print(p.map(f,[2,2,2],[3,4,5]))

消息如下：

TypeError                                 Traceback (most recent call last) <ipython-input-25-e9ce49d0ccbf> in <module>
      1 p = multiprocess.pool.Pool()
      2 # result = p.map(for_multical,[N]*n,[k]*n)
----> 3 print(p.map(f,[2,2,2],[3,4,5]))
      4 p.close()
      5 p.join()

D:\software\python\lib\site-packages\multiprocess\pool.py in map(self, func, iterable, chunksize)
    362         in a list that is returned.
    363         '''
--> 364         return self._map_async(func, iterable, mapstar, chunksize).get()
    365 
    366     def starmap(self, func, iterable, chunksize=None):

D:\software\python\lib\site-packages\multiprocess\pool.py in
_map_async(self, func, iterable, mapper, chunksize, callback, error_callback)
    483 
    484         task_batches = Pool._get_tasks(func, iterable, chunksize)
--> 485         result = MapResult(self, chunksize, len(iterable), callback,
    486                            error_callback=error_callback)
    487         self._taskqueue.put(

D:\software\python\lib\site-packages\multiprocess\pool.py in
__init__(self, pool, chunksize, length, callback, error_callback)
    795         self._value = [None] * length
    796         self._chunksize = chunksize
--> 797         if chunksize <= 0:
    798             self._number_left = 0
    799             self._event.set()

TypeError: '<=' not supported between instances of 'list' and 'int'

self._chunksize = chunksize chunksize似乎塊大小未分配。 這怎么可能發生？ 如何解決這個問題？

包“多進程”也有同樣的問題。

Answer 1

Pool.map()與常規map() ) 的不同之處在於它只接受一個可迭代對象。 解決方案是使用.starmap()代替，但它需要其他格式的迭代，請參閱鏈接文檔。

print(p.starmap(f, zip([2,2,2],[3,4,5]) ))