Redis集群string/hash测试
| 名称 | 信息 |
|---|---|
| Redis版本 | 6.0.9 |
| OS | Linux |
| master节点端口 | 9002,9003,9004 |
| slave节点端接口 | 9001,9005,9006 |
以下计算只需要计算master节点，slave节点不必计算
初始化占用内存
[116.198.162.25:9005] VIRT: 2.59M RSS: 13.36M Peak: 122.72M Max: 0B System: 15.51G
[116.198.162.25:9004] VIRT: 2.58M RSS: 16.43M Peak: 141.75M Max: 0B System: 15.51G
[116.198.162.25:9002] VIRT: 2.60M RSS: 13.95M Peak: 136.43M Max: 0B System: 15.51G
[116.198.162.25:9001] VIRT: 2.59M RSS: 15.24M Peak: 134.04M Max: 0B System: 15.51G
[116.198.162.25:9006] VIRT: 2.60M RSS: 15.65M Peak: 74.17M Max: 0B System: 15.51G
[116.198.162.25:9003] VIRT: 2.64M RSS: 15.87M Peak: 94.24M Max: 0B System: 15.51G
总内存：2.58+2.60+2.64 = 7.82m
7位纯数字测试
value
[116.198.162.25:9005] VIRT: 21.74M RSS: 29.18M Peak: 122.72M Max: 0B System: 15.51G
[116.198.162.25:9004] VIRT: 37.13M RSS: 47.61M Peak: 141.75M Max: 0B System: 15.51G
[116.198.162.25:9002] VIRT: 40.73M RSS: 51.83M Peak: 136.43M Max: 0B System: 15.51G
[116.198.162.25:9001] VIRT: 37.11M RSS: 44.16M Peak: 134.04M Max: 0B System: 15.51G
[116.198.162.25:9006] VIRT: 34.99M RSS: 42.93M Peak: 74.17M Max: 0B System: 15.51G
[116.198.162.25:9003] VIRT: 37.16M RSS: 46.55M Peak: 94.24M Max: 0B System: 15.51G
总内存：37.13+40.73+37.16-7.82 = 107.2m
计算：每天加一个k-v增加112字节，
112*1000000 = 106.81m
hash
[116.198.162.25:9005] VIRT: 5.95M RSS: 15.68M Peak: 122.72M Max: 0B System: 15.51G
[116.198.162.25:9004] VIRT: 5.84M RSS: 18.08M Peak: 141.75M Max: 0B System: 15.51G
[116.198.162.25:9002] VIRT: 5.94M RSS: 18.78M Peak: 136.43M Max: 0B System: 15.51G
[116.198.162.25:9001] VIRT: 5.84M RSS: 16.66M Peak: 134.04M Max: 0B System: 15.51G
[116.198.162.25:9006] VIRT: 5.90M RSS: 14.41M Peak: 74.17M Max: 0B System: 15.51G
[116.198.162.25:9003] VIRT: 5.95M RSS: 16.68M Peak: 94.24M Max: 0B System: 15.51G
总内存：5.94+5.95+5.84-7.82 = 9.91m
计算：每添加一个key-entry增加128字节（hash表本身也需要带有一些信息），每添加内部key-value增加8字节（int类型，4+4=8），
128*1001 - 8*1001 + 8*1000000 = 7.74m
string测试，默认value: 18888888888terryterryterryterryterryterryterryterry 51B
value
[116.198.162.25:9005] VIRT: 54.91M RSS: 62.37M Peak: 122.72M Max: 0B System: 15.51G
[116.198.162.25:9004] VIRT: 54.96M RSS: 62.77M Peak: 141.75M Max: 0B System: 15.51G
[116.198.162.25:9002] VIRT: 54.90M RSS: 62.70M Peak: 136.43M Max: 0B System: 15.51G
[116.198.162.25:9001] VIRT: 54.94M RSS: 62.37M Peak: 134.04M Max: 0B System: 15.51G
[116.198.162.25:9006] VIRT: 54.92M RSS: 60.97M Peak: 74.17M Max: 0B System: 15.51G
[116.198.162.25:9003] VIRT: 54.95M RSS: 61.38M Peak: 94.24M Max: 0B System: 15.51G
总内存：54.96+54.90+54.95-7.82 = 156.99
计算：每添加一个k-v增加168字节
168*1000000 = 160.22m
hash
[116.198.162.25:9005] VIRT: 21.24M RSS: 37.23M Peak: 122.72M Max: 0B System: 15.51G
[116.198.162.25:9004] VIRT: 20.54M RSS: 37.73M Peak: 141.75M Max: 0B System: 15.51G
[116.198.162.25:9002] VIRT: 21.17M RSS: 38.38M Peak: 136.43M Max: 0B System: 15.51G
[116.198.162.25:9001] VIRT: 20.53M RSS: 34.56M Peak: 134.04M Max: 0B System: 15.51G
[116.198.162.25:9006] VIRT: 20.90M RSS: 35.75M Peak: 74.17M Max: 0B System: 15.51G
[116.198.162.25:9003] VIRT: 20.96M RSS: 35.92M Peak: 94.24M Max: 0B System: 15.51G
总内存：20.54+21.17+20.96-7.82 = 54.85m
计算：128*1001 + (51+4)*1000000 = 52.57m
总结
1.纯数字类型object encoding=int,用普通方式存每个k-v需要112字节,本身只需要8字节现在额外多了100多字节
String类型需要额外的内存空间记录数据长度、空间使用 等元数据，当缓存的数据较小，元数据的空间开销很大，显得喧宾夺主。,浪费空间
而使用hash来存,object encoding=ziplist,k-v占用8字节。所以数据越小使用hash削过越明显
2.一个键值对占用内存120字节左右，如果用hash能够将低到50字节以下，减少两倍内存占用。不过以下几点导致无法使用hash
- 集群环境下无法使用Redis事务，从而不能保证hset后再设置expire原子性
- 如果直接hset的话，所用的时间和set一样，但是hset还要执行一次expire，导致所用时间翻倍。
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