mysql4.0做主从时主库的备份脚本

    mysql4.0是老版本了，但是有些早期使用的企业依然在用，在创建主从时特别是线上服务器创建主从时，保证数据的一致性是个大问题：比如创建完从库同步时出现重复数据重复执行（虽然数据条数一致，但数据有可能会不一致）等。在mysql5.0以上版本中，此时备份主库只用在mysqldump时加上-F、master-data=2，single-transaction参数，从库同步时导入备份，在取备份文件开头的bin-log和pos位置进行同步即可，不会出现数据重复执行等问题，他能确保同步时的一致性。比较悲剧的是，本人所用的数据库还没有升级，是4.0的版本，经过测试，写了一个专一用于4.0主从同步时主库备份的脚本，原理就是模拟5.0以上的备份过程来做的。也可以用于5.0以上的版本，但是5.0以上的版本没有必要这么做。大家可以参考。

 

#!/usr/bin/env python
# -*- coding: utf-8 -*-
#last update:2012-10-25

import os,sys,time,MySQLdb
import subprocess,threading

class mysql_dump():

    def __init__(self):
        self.STAT_IP = "192.168.1.110"
        self.logfile = "/data/script/db_back/mysql_dump.log"
        self.user = "dump"
        self.passwd = "123456"
        self.distid = "2"

    def log_w(self,text):
        now = time.strftime("%Y-%m-%d %H:%M:%S")
        tt = str(now) + "\t" + str(text) + "\n"
        f = open(self.logfile,'a+')
        f.write(tt)
        f.close()

    def dump(self,dumpname,now):
        cmd = "/usr/local/mysql/bin/mysqldump -A -Q -e --add-drop-table --add-locks --extended-insert --quick --no-autocommit --single-transaction -u%s -p%s | bzip2 -2 > %s" % (self.user,self.passwd,dumpname)
        print time.strftime("%Y-%m-%d %H:%M:%S")
        text = "Start mysqldump,Please wait ..."
        print text
        self.log_w(text)
        a = subprocess.Popen(cmd,shell=True)
        while 1:
            b = subprocess.Popen.poll(a)
            if b == 0:
                text = "Mysqldump complete"
                print text
                self.log_w(text)
                break
            elif b is None:
                print  'Mysqldump running'
                time.sleep(30)
            else:
                print a.pid,'term'
                break
        self.rsync(dumpname)

    def rsync(self,dumpname):
        cmd = "rsync -az %s %s::asktao_db/db_back/" % (dumpname,self.STAT_IP)
        text = "Start rsync to server(%s) ,Please wait ..." % self.STAT_IP
        print text
        self.log_w(text)
        a = subprocess.Popen(cmd,shell=True)
        while 1:
            b = subprocess.Popen.poll(a)
            if b == 0:
                text = "Rsync complete"
                print text
                self.log_w(text)
                break
            elif b is None:
                print  'Rsync running'
                time.sleep(30)
            else:
                print a.pid,'term'
                break

    def bin_log(self):
        try:
            conn = MySQLdb.connect(host = '127.0.0.1',user = 'repl_monitor',passwd = '123456',connect_timeout=5)
            cursor = conn.cursor()
            cursor.execute("show master status")
            alldata = cursor.fetchall()
            cursor.close()
            conn.close()
            file = alldata[0][0]
            Position = alldata[0][1]
            text = "show master status: %s  %s" % (file,Position)
            print text
            self.log_w(text)
            return file,Position
        except MySQLdb.Error,e:
            text = e.args
            print text
            self.log_w(text)
            sys.exit()

    def lock(self):
        try:
            conn = MySQLdb.connect(host = 'localhost',user = self.user,passwd = self.passwd,connect_timeout=5)
            cursor = conn.cursor()
            text = "flush tables with read lock"
            print text
            self.log_w(text)
            cursor.execute("flush tables with read lock")
            text = "flush logs"
            print text
            self.log_w(text)
            cursor.execute("flush logs")
            file,Position = self.bin_log()
            now = time.strftime("%Y%m%d%H%M")
            dumpname = "/data/script/db_back/wd_%s_%s_%s_%s.bz2" % (self.distid,now,file,Position)
            d = threading.Thread(target=self.dump, args=(dumpname,now))
            d.start()
            while 1:
                if os.path.isfile(dumpname) and os.path.getsize(dumpname) > 0:
                    text = "UNLOCK TABLES"
                    print text
                    self.log_w(text)
                    cursor.execute("UNLOCK TABLES")
                    cursor.close()
                    conn.close()
                    break
        except MySQLdb.Error,e:
            text = e.args
            print text
            self.log_w(text)
            sys.exit()

    def work(self):
        t = threading.Thread(target=self.lock, args=())
        t.start()


if __name__ == "__main__":
    boss = mysql_dump()
    boss.work()