Jupyter Notebook中的Python多處理不起作用

Question

我是Python中的multiprocessing模塊的新手，並且使用Jupyter筆記本。 當我嘗試運行以下代碼時，我不斷得到AttributeError: Can't get attribute 'load' on <module '__main__' (built-in)>

當我運行文件時沒有輸出，它只是繼續加載。

import pandas as pd
import datetime
import urllib
import requests
from pprint import pprint
import time
from io import StringIO
from multiprocessing import Process, Pool

symbols = ['AAP']

start = time.time()
dflist = []

def load(date):
    if date is None:
        return
    url = "http://regsho.finra.org/FNYXshvol{}.txt".format(date)
    try:
        df = pd.read_csv(url,delimiter='|')
        if any(df['Symbol'].isin(symbols)):
            stocks = df[df['Symbol'].isin(symbols)]
            print(stocks.to_string(index=False, header=False))
            # Save stocks to mysql
        else:
            print(f'No stock found for {date}' )
    except urllib.error.HTTPError:
        pass

pool = []
numdays = 365
start_date = datetime.datetime(2019, 1, 15 )  #year - month - day
datelist = [
        (start_date - datetime.timedelta(days=x)).strftime('%Y%m%d') for x in range(0, numdays)
        ]

pool = Pool(processes=16)
pool.map(load, datelist)

pool.close()
pool.join()

print(time.time() - start)

如何直接從筆記本運行此代碼而不會出現問題？

Answer 1

一種方法：
1.獲取load函數並創建例如worker.py
2. import worker and worker.load
3。

from multiprocessing import Pool
import worker
if __name__ ==  '__main__': 
  pool = []
  numdays = 365
  start_date = datetime.datetime(2019, 1, 15 )  #year - month - day
  datelist = [
        (start_date - datetime.timedelta(days=x)).strftime('%Y%m%d') for x in 
        range(0, numdays)
        ]

  pool = Pool(processes=16)
  pool.map(worker.load, datelist)

  pool.close()
  pool.join()