Python：函数挂在子进程中

Question

我编写了此脚本，该脚本使用exchangelib python API登录我的Microsoft Exchange帐户并下载包含特定主题的已发送消息。

我将其分为两个函数，每个函数作为单独的进程运行：

功能A从我的帐户中提取电子邮件，并将与特定主题匹配的电子邮件放入队列。

功能B从队列中获取这些电子邮件并将其保存到磁盘中。

这些功能在单个进程中运行时正常工作，但是当我决定在子进程中运行功能A而功能B在主进程中运行时，功能A挂在下载电子邮件的行上。

我的代码在下面。

from exchangelib import Credentials, Account, Mailbox, HTMLBody, Message

import multiprocessing as mp
from multiprocessing import Process, Queue


def authenticate(user_id, passw):
    credentials = Credentials(user_id, passw)
    exchange = Account(account_id, credentials=credentials, autodiscover=True)
    return exchange

def fetch_bounces(exchange, output_q, progress):
    print('fetcher process started')
    while exchange.inbox.total_count != 0:
        exchange.inbox.refresh()
        inbox=exchange.inbox.all()
        for msg in inbox:
            if 'Undeliverable:' in msg.subject:
                output_q.put(msg.display_to)
        inbox.move_to_trash()
    progress.put('done')

def save_bounced(outputfile, output_q):
    bounces = []
    while output_q.empty() is False:
        lead = output_q.get()
        print('bounce: '+lead)
        bounces.append(lead)
    if len(bounces)>0:
        existing = []
        try:
            with open(outputfile, 'r+') as f:
                lines = f.readlines()
                existing = [line.strip().lower() for line in lines]
        except:
            pass
        with open(outputfile, 'a+') as f:
            for line in bounces:
                if line.strip().lower() in existing:
                    continue
                else:
                    f.write(line.strip().lower()+'\n')

if __name__ == '__main__':
    #credentials
    account_id =
    password = 


    #set Queues to store bounces and progress
    bounced = Queue()
    progress = Queue()

    #login to exhcnage
    exchange = authenticate(account_id, password)
    print('logged in successfully')

    #spawn bounce fetching process and start it
    f_process = Process(target=fetch_bounces, args=(exchange, bounced, progress))
    f_process.start()

    #define file path where bounces will be stored
    output_f = 'bounces.txt'

    #while new bounce emails are being fetch, remain in loop and also specify flag to know when all emails have been fetched

    complete = False
    while not complete:
        save_bounced(output_f, bounced)
        try:
            msg = progress.get(block=False)
            if msg == 'done':
                complete =  True
        except:
            pass

    #terminate fetcher process

    f_process.join()

    print('bounces completely removed')

Answer 1

使用多重处理时，所有参数都必须可序列化。但是Account实例不能安全地序列化。您必须在每个进程中创建Account实例。