利用python list完成最简单的DB连接池方法

'''遇到问题没人解答？小编创建了一个Python学习交流QQ群：857662006 寻找有志同道合的小伙伴，互帮互助,群里还有不错的视频学习教程和PDF电子书！'''#!/usr/bin/env python3# -*- coding: UTF-8 -*-import pymysqlimport randomimport time# 初始化mysql 连接池def MySQLInit(mysql_host,mysql_port,mysql_user,mysql_password,mysql_charset,mysql_dbname,mysql_maxconnect):  # 定义返回mysql连接池的类型，这里定义为 list     return_db_list = []  for Connect in range(0,mysql_maxconnect):    try:      db = pymysql.connect(        host = mysql_host ,         port = mysql_port ,         user = mysql_user ,         passwd = mysql_password ,        db = mysql_dbname ,        charset = mysql_charset       )      print ("连接MySQL数据库成功，MySQL数据库ID为:%s" %(db))      return_db_list.append(db)    except Exception as e:      print ("连接MySQL数据库出错")      print (e)  # 如果mysql连接池为空，则返回-1  if 0 == len(return_db_list):    print ("错误 , 连接MySQL数据库失败,连接池为0")    return -1  else:    # 返回mysql连接池    return return_db_listdef Pull_DB_Connect(mysql_host,mysql_port,mysql_user,mysql_password,mysql_charset,mysql_dbname , MySQL_Connect_Pool , mysql_maxconnect) :    # 打印补充前的mysql连接数  print ("补充前MySQL连接数为:",len(MySQL_Connect_Pool))    # 循环相差的连接数  for Connect in range((len(MySQL_Connect_Pool)) , mysql_maxconnect):    try:      db = pymysql.connect(        host = mysql_host ,         port = mysql_port ,         user = mysql_user ,         passwd = mysql_password ,        db = mysql_dbname ,        charset = mysql_charset       )      print ("重新补充，连接MySQL数据库成功，MySQL数据库ID为:%s" %(db))      # 将刚刚连接成功的DB连接追加到MySQL_Connect_Pool中      MySQL_Connect_Pool.append(db)    except Exception as e:      print ("重新补充，连接MySQL数据库出错")      print (e)  if 0 == len(MySQL_Connect_Pool):    print ("错误 , 连接MySQL数据库失败,连接池为0")    return -1  else:    # 打印连接池总数并且返回    print("Mysql 连接池总数为:" , len(MySQL_Connect_Pool))    return MySQL_Connect_Pool def main() :  # 定义测试mysql信息  mysql_host = "192.168.1.100"  mysql_port = 3306  mysql_user = "liwang"   mysql_password = "liwang"  mysql_charset = "utf8"  mysql_dbname = "itchat"  mysql_maxconnect = 3  # 初始化mysql连接池  MySQL_Connect_Pool = MySQLInit(mysql_host,mysql_port,mysql_user,mysql_password,mysql_charset,mysql_dbname,mysql_maxconnect)  # 定义初始化sql   sql = "show databases;"    while True:    # 随机获连接池的下标    db_link = random.randint(0,len(MySQL_Connect_Pool)-1)    try:      # 执行sql       cursor = MySQL_Connect_Pool[db_link].cursor()      cursor.execute(sql)      print (cursor.fetchall())    except Exception as e:      # 如果执行失败，模拟为DB连接失效，则打印错误信息，删除错误的MySQL_Connect_Pool信息      print (e)      del MySQL_Connect_Pool[db_link]      print ("数据库无法连接，删除Mysql连接池下标:" , db_link)      # 重新补充mysql连接池      Pull_DB_Connect(mysql_host,mysql_port,mysql_user,mysql_password,mysql_charset,mysql_dbname,MySQL_Connect_Pool,mysql_maxconnect)        # 休眠10s     time.sleep(10)if __name__ == "__main__" :  main()