黑猴子的家：Redis 事务 之 秒杀案例

Code -> GigHub

https://github.com/liufengji/redis_seckill.git

1、解决计数器和人员记录的事务操作

2、超卖问题

3、ab压力测试

apache ab, loadrunner , jmeter 这三个都是压力测试工具
ab压力测试，没有图形化界面，用起来方便小巧，只能测试页面 http 之类的

[root@hadoop102 ~]# ab --help
ab: wrong number of arguments
Usage: ab [options] [http[s]://]hostname[:port]/path
Options are:
    -n requests     Number of requests to perform        //多少次请求
    -c concurrency  Number of multiple requests to make   //多少并发量
    -t timelimit    Seconds to max. wait for responses
    -b windowsize   Size of TCP send/receive buffer, in bytes
    -p postfile     File containing data to POST. Remember also to set -T
    -u putfile      File containing data to PUT. Remember also to set -T
    -T content-type Content-type header for POSTing, eg.
                    'application/x-www-form-urlencoded'
                    Default is 'text/plain'
    -v verbosity    How much troubleshooting info to print
    -w              Print out results in HTML tables
    -i              Use HEAD instead of GET
    -x attributes   String to insert as table attributes
    -y attributes   String to insert as tr attributes
    -z attributes   String to insert as td or th attributes
    -C attribute    Add cookie, eg. 'Apache=1234. (repeatable)
    -H attribute    Add Arbitrary header line, eg. 'Accept-Encoding: gzip'
                    Inserted after all normal header lines. (repeatable)
    -A attribute    Add Basic WWW Authentication, the attributes
                    are a colon separated username and password.
    -P attribute    Add Basic Proxy Authentication, the attributes
                    are a colon separated username and password.
    -X proxy:port   Proxyserver and port number to use
    -V              Print version number and exit
    -k              Use HTTP KeepAlive feature
    -d              Do not show percentiles served table.
    -S              Do not show confidence estimators and warnings.
    -g filename     Output collected data to gnuplot format file.
    -e filename     Output CSV file with percentages served
    -r              Don't exit on socket receive errors.
    -h              Display usage information (this message)
    -Z ciphersuite  Specify SSL/TLS cipher suite (See openssl ciphers)
    -f protocol     Specify SSL/TLS protocol (SSL2, SSL3, TLS1, or ALL)

127.0.0.1:6379> set sk:0101:qt 10
ok

127.0.0.1:6379> get sk:0101:qt
ok

127.0.0.1:6379> smembers sk:0101:usr
1) "1624"
2) "5624"
3) "1724"
4) "1626"
5) "1936"
6) "6272"
7) "9254"
8) "9022"
9) "2345"
10) "8643"

[root@hadoop102 ~]# ab -n 1000 -c 100 http://192.168.67.1:8000/seckill/

[root@hadoop102 ~]# vim /root/postfile
Prodid=0101&
注:结尾必须用&符号

[root@hadoop102 ~]# ab -n 200 -c 50 -p /root/postfile \
-T 'application/x-www-form-urlencoded' http://192.168.67.1:8080/seckill/doseckill

注：-n 一共发送多少请求
-c  一共并发多少
-P  post请求 内容放到文件里面 用&符号链接和结尾
-T   修改请求数据的格式

3、利用乐观锁淘汰用户，解决超卖问题

注：具体看代码，此处会有异常，链接超时和未抢完现象
链接超时，引入链接池后，会完美解决
未抢完现象，有两种方法，使用消息队列或LUA
Redis 支持 LUA 脚本

4、链接池

节省每次连接redis服务带来的消耗，把连接好的实例反复利用

通过参数管理连接的行为

5、链接池参数

MaxTotal
控制一个pool可分配多少个jedis实例，通过pool.getResource()来获取；如果赋值为-1，则表示不限制；如果pool已经分配了MaxTotal个jedis实例，则此时pool的状态为exhausted。

maxIdle
控制一个pool最多有多少个状态为idle(空闲)的jedis实例；

MaxWaitMillis
表示当borrow一个jedis实例时，最大的等待毫秒数，如果超过等待时间，则直接抛JedisConnectionException；

testOnBorrow
获得一个jedis实例的时候是否检查连接可用性（ping()）；如果为true，则得到的jedis实例均是可用的；