利用python list 完成最简单的DB连接池

先来看查看效果:

在代码连接数据库后，并且执行三条sql后，将mysql直接重启掉，故我们的连接池连接均是不ok的，所以，它会全部删除再抓新的连接下来，重启mysql命令:

关于python代码:

#!/usr/bin/env python3
# -*- coding: UTF-8 -*-

import pymysql
import random
import 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_list

def 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()