为什么我的 python 脚本执行了 3 次？

Question

我有以下脚本执行了三次，但我不知道为什么

#!C:/Python38-32/python.exe

#script.py

from py_get_data_from_game import main

from multiprocessing import Pool

import connect_to_db

import mysql.connector

from mysql.connector import Error

connection = connect_to_db.connect()

user_names = []

passwords = []

    

print('START')  

try:

    connection = connect_to_db.connect()

    if connection.is_connected():

        sql_select_Query = "select * from players"

        cursor = connection.cursor(dictionary=True)

        cursor.execute(sql_select_Query)

        records = cursor.fetchall()

        for row in records:

            user_names.append(row['user_name'])

            passwords.append(row['password'])

except Error as e:

    print("Error while connecting to MySQL", e)

finally:

    if (connection.is_connected()):

        cursor.close()

        connection.close()

        print("MySQL connection is closed")

        

if __name__ == '__main__':

    pool = Pool(2) # two parallel jobs

    results = pool.map(main, zip(user_names, passwords))

输出：

C:\scripts>script.py

START

MySQL connection is closed

START

MySQL connection is closed

START

MySQL connection is closed

Answer 1

当您使用时multiprocessing，python 需要创建与您的程序碰巧指定的进程一样多的进程，并具有相同的环境（我的意思是imports）。它通过再次运行您的脚本来完成此操作。为避免同时执行虚假代码，您应该将其放在：if __name__ == '__main__':