redis优化记录

某日，DBA发现针对redis的ttl操作过多，如下：

1585835992.720145 [2 10.160.91.30:9291] "TTL" "activity::activity_price:7:71302"
1585835992.721121 [2 10.160.82.69:51447] "TTL" "activity::activity_price:7:72147"
1585835992.721170 [2 10.160.91.30:26069] "TTL" "activity::activity_price:7:49075"
1585835992.721654 [0 10.160.91.30:57862] "SELECT" "2"
1585835992.721678 [2 10.160.91.30:9291] "GET" "activity::activity_price:7:71302"
1585835992.722339 [2 10.160.82.69:51447] "TTL" "activity::activity_price:7:71675"
1585835992.722592 [2 10.160.91.30:26069] "GET" "activity::activity_price:7:49075"
1585835992.723112 [2 10.160.91.30:57862] "TTL" "activity::activity_info:7"
1585835992.723229 [2 10.160.91.30:9291] "TTL" "activity::activity_price:7:70826"
1585835992.723551 [2 10.160.82.69:51447] "TTL" "activity::activity_price:7:141"
1585835992.724038 [2 10.160.91.30:26069] "TTL" "activity::activity_price:7:50901"
1585835992.724610 [2 10.160.91.30:57862] "GET" "activity::activity_info:7"

经查代码发现是下面的代码造成的：（在每次get数据的时候都会进行ttl操作，这样使得ttl操作变得很多，redis的qps访问量很高）

后来我问DBA，qps过高对咱们有什么影响啊？

DBA：会导致cpu使用率增加很多。

我：cpu使用率增加很多对咱们有什么影响啊？

DBA：使用率高，响应就会变慢啊。如果流量很高，cpu跑满也是有可能。目前单机的大概能支撑几万qps，集群版随节点数翻倍。