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一个秒杀系统的例子分析
使用chan使得所有的请求在单实例中串行处理,是否会降低吞吐?
我理解本地库存最主要的目的,应该是当本地库存不足时,不去请求redis。保证本地库存源子操作这种需求源子操作或者用lock就可以解决,不必让所有请求的串行处理吧。
而且go chan底层也是基于lock实现的,通过benchmark chan 没体现出任何优势。
如果理解错误点 还望指正。
大佬你好,我是Go语言中文网(https://studygolang.com )站长,看到你这个项目,很赞,我想分享给更多的 Go 语言爱好者。特向你申请授权我发布到网站和对应的公众号等渠道。因为会大量引用README中的内容,期待您的回复!谢谢!
if localSpike.LocalDeductionStock() && remoteSpike.RemoteDeductionStock(redisConn) {
util.RespJson(w, 1, "抢票成功", nil)
LogMsg = LogMsg + "result:1,localSales:" + strconv.FormatInt(localSpike.LocalSalesVolume, 10)
} else {
util.RespJson(w, -1, "已售罄", nil)
LogMsg = LogMsg + "result:0,localSales:" + strconv.FormatInt(localSpike.LocalSalesVolume, 10)
}
失败应该回滚本地的一个记录
if localSpike.LocalDeductionStock() && remoteSpike.RemoteDeductionStock(redisConn) {
util.RespJson(w, 1, "抢票成功", nil)
LogMsg = LogMsg + "result:1,localSales:" + strconv.FormatInt(localSpike.LocalSalesVolume, 10)
} else {
util.RespJson(w, -1, "已售罄", nil)
spike.LocalSalesVolume = spike.LocalSalesVolume - 1
LogMsg = LogMsg + "result:0,localSales:" + strconv.FormatInt(localSpike.LocalSalesVolume, 10)
}
lua 脚本 >= 情况下会超卖一个,所以改成>
把库存分配到本地机器的机制是怎样的,在什么时机或以什么方式进行,怎样保证数据的一致性,如果 一台机器分配时没有成功,这台机器没有了库存,落在此机器上的请求会不会买不到票?
感觉最后可以加一步,当余票很少时,也许把用户id本地hash,少于多少(比如还有10张票,QPS1w,用hash值少于多少卡掉99%的请求,使qps就100(为余票个数*10)就行)的直接返空,直接显示售罄了,这样让大部分本地库存不用再去请求redis远程减库存。
readme里lua脚本
if(ticket_sold_nums > ticket_total_nums) then
return redis.call('HINCRBY', ticket_key, ticket_sold_key, 1)
end
应该是
ticket_total_nums > ticket_sold_nums
代码里是对的
1、如何临时追加库存
2、扣费成功后,发送mq失败怎么处理?
3、mq可能存在丢消息的情况;
4、redis数据可能存在丢失,如何处理?
如果分库server的库存减和总redis库存减的操作是原子操作这个是前提的话,8点放票,此时库存都是足够的,瞬间所有的分仓库都会去请求Redis。100W并发请求,就可能有绝大多数的请求同样也会去Redis。 这个问题如何解决。单单去增加redis服务器的并发能力吗?
对最后一张图不是很理解这个消息队列的操作时机
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