4、Redis的小功能大用处
前言
1、慢查询分析
所谓的慢查询日志,就是在命令的执行前后计算每条命令的执行时间,当超过预设值,就将这条命令的相关信息记录下来,
redis命令执行分为4个步奏,发送命令,命令排队,执行命令,返回结果,这里的慢查询分析值统计执行命令的时间。
1、慢查询的2个配置参数
1、首先我们看了上面的介绍需要明白两件事
1、预设阀值如何设置
慢查询的预设阀值 slowlog-log-slower-than
slowlog-log-slower-than参数就是预设阀值,单位是微秒,默认值是1000,也就是10毫秒,如果一条命令的执行时间超过10000微妙,那么它将被记录在慢查询日志中。
如果slowlog-log-slower-than的值是0,则会记录所有命令。
如果slowlog-log-slower-than的值小于0,则任何命令都不会记录日志。
2、慢查询的记录在哪里
慢查询日志的长度slowlog-max-len
slowlog-max-len只是说明了慢查询日志最多存储多少,从字面意思看这个只是说明日志最多存储多少条几率,并没有说存到哪里,实际上redis使用了一个列表来存储慢查询日志,这个值就是列表的最大长度,当一个新的命令满足慢查询条件的时候就会被插入到这个列表中,当慢查询日志已经到达列表的最大长度时,又有慢查询日志要进入列表,则最早插入列表的日志将会被移出列表,新日志被插入列表的末尾。比如设置了5,当放入第6条的时候,第一条就会出列
2、修改配置的方法
1、通过配置文件修改
2。使用命令动态修改
config set slowlog-log-slower-than 2000
config set slowlog-max-len 1000
//将配置持久化到本地配置文件,
config rewrite
3、查看慢查询日志
虽然慢查询日志在Redis内存列表中,但是Redis并没有暴露这个列表的主键,而是通过一组命令来访问和管理的
1、获取慢查询日志
slowlog get n(n可以指定条数) 分别是查询日志的标识id,发送时间戳,命令耗时,执行命令,以及参数
127.0.0.1:6379> config set slowlog-log-slower-than 0
OK
127.0.0.1:6379> set name healerjean
OK
127.0.0.1:6379> slowlog get
1) 1) (integer) 1
2) (integer) 1523587843
3) (integer) 5
4) 1) "set"
2) "name"
3) "healerjean"
5) "127.0.0.1:49894"
6) ""
2) 1) (integer) 0
2) (integer) 1523587826
3) (integer) 5104
4) 1) "config"
2) "set"
3) "slowlog-log-slower-than"
4) "0"
5) "127.0.0.1:49894"
6) ""
127.0.0.1:6379>
2、获取慢查询的列表当前的长度
当前有3条慢查询记录
127.0.0.1:6379> slowlog len
(integer) 3
127.0.0.1:6379>
3、慢查询日志重置,实际上就是对列表进行清理
127.0.0.1:6379> slowlog reset
OK
2、最佳实战慢查询
慢查询功能能够帮我们找到Redis可能存在的瓶颈,但是在实际中主要建议下面得几点
1、slowlog-max-len配置建议
线上建议调大慢查询列表,记录慢查询的时候Reids会对长命令做拦截判断,并不会占用大量内存,增大查询列表可以减缓慢查询的被剔除的可能(因为超过长度就会将老的删除,我们后来就看不到了),例如线上可以设置1000以上
2、showlog-log-slower-than 建议配置,默认超过10毫秒判断为慢查询,其实是需要根据Redis并发量调整这个值,对于高流量的场景,建议设置为1毫秒
3、因为redis有排队机制,慢查询也可能造成其他命令阻塞,因此客户端出现命令超时的时候,需要检测该时间带你是是因为慢查询导致的阻塞
4、这里牛逼了,慢查询是一种先进先出的队列,也就是说当慢查询比较多的时候回丢失部分慢查询的。为了防止这种现象发生,可以将它持久化到其他存储中(mysql),然后使用可视化工具进行查看,
2、Redis Shell
1、redis-server
我们知道它是用来启动redis的,但是他还有一个–test-memory选项,用来检测当前操作系统能否稳定分配给指定容量的的内存给Redis,有效避免因为内存问题造成的崩溃
时间比较长,需要耐心等待
healerjean$ redis-server --test-memory 1024
Addressing test [1]
Please keep the test running several minutes per GB of memory.
Also check http://www.memtest86.com/ and http://pyropus.ca/software/memtester/
Your memory passed this test.
Please if you are still in doubt use the following two tools:
1) memtest86: http://www.memtest86.com/
2) memtester: http://pyropus.ca/software/memtester/
JeandeMBP:bin healerjean$
一般情况下,不需要每次开启Redis,都执行这个选项,这个功能更偏向于调节测试。
3、redis-benchmark
这个可以为Redis做基准性能测试,它提供了很多选项帮助开发和运行人员测试Redis的性能
1、-c (client) 代码客户端的并发数量,默认是50
2、-n 代表客户端请求的总量 默认是1000000
-n(num)
healerjean$ redis-benchmark -c 100 -n 20000
代表100个客户同时请求redis,一共执行20000次
redis-benchmark会对各类数据结构的命令进行测试,并给出指标
比如下面的get,一共执行了20000次,在0.19秒完成,每个数据请求是3个字节,98.58%小于2毫秒
====== GET ======
20000 requests completed in 0.19 seconds
100 parallel clients
3 bytes payload
keep alive: 1
98.58% <= 1 milliseconds
99.82% <= 2 milliseconds
100.00% <= 2 milliseconds
104712.04 requests per second
healerjean$ redis-benchmark -c 100 -n 20000
====== PING_INLINE ======
20000 requests completed in 0.20 seconds
100 parallel clients
3 bytes payload
keep alive: 1
87.22% <= 1 milliseconds
99.93% <= 2 milliseconds
100.00% <= 2 milliseconds
101522.84 requests per second
====== PING_BULK ======
20000 requests completed in 0.20 seconds
100 parallel clients
3 bytes payload
keep alive: 1
74.24% <= 1 milliseconds
100.00% <= 2 milliseconds
100.00% <= 2 milliseconds
98522.17 requests per second
====== SET ======
20000 requests completed in 0.20 seconds
100 parallel clients
3 bytes payload
keep alive: 1
91.82% <= 1 milliseconds
99.36% <= 2 milliseconds
99.85% <= 3 milliseconds
100.00% <= 3 milliseconds
99502.48 requests per second
====== GET ======
20000 requests completed in 0.19 seconds
100 parallel clients
3 bytes payload
keep alive: 1
98.58% <= 1 milliseconds
99.82% <= 2 milliseconds
100.00% <= 2 milliseconds
104712.04 requests per second
====== INCR ======
20000 requests completed in 0.20 seconds
100 parallel clients
3 bytes payload
keep alive: 1
89.14% <= 1 milliseconds
99.82% <= 2 milliseconds
100.00% <= 2 milliseconds
100000.00 requests per second
====== LPUSH ======
20000 requests completed in 0.20 seconds
100 parallel clients
3 bytes payload
keep alive: 1
83.86% <= 1 milliseconds
99.93% <= 2 milliseconds
100.00% <= 2 milliseconds
101522.84 requests per second
====== RPUSH ======
20000 requests completed in 0.19 seconds
100 parallel clients
3 bytes payload
keep alive: 1
92.49% <= 1 milliseconds
99.79% <= 2 milliseconds
100.00% <= 2 milliseconds
103092.78 requests per second
====== LPOP ======
20000 requests completed in 0.22 seconds
100 parallel clients
3 bytes payload
keep alive: 1
87.38% <= 1 milliseconds
99.97% <= 2 milliseconds
100.00% <= 2 milliseconds
92592.59 requests per second
====== RPOP ======
20000 requests completed in 0.20 seconds
100 parallel clients
3 bytes payload
keep alive: 1
94.17% <= 1 milliseconds
99.57% <= 2 milliseconds
100.00% <= 2 milliseconds
102040.82 requests per second
====== SADD ======
20000 requests completed in 0.20 seconds
100 parallel clients
3 bytes payload
keep alive: 1
96.68% <= 1 milliseconds
99.47% <= 2 milliseconds
99.50% <= 5 milliseconds
99.54% <= 6 milliseconds
99.60% <= 7 milliseconds
99.83% <= 8 milliseconds
100.00% <= 8 milliseconds
101010.10 requests per second
====== HSET ======
20000 requests completed in 0.19 seconds
100 parallel clients
3 bytes payload
keep alive: 1
71.61% <= 1 milliseconds
100.00% <= 1 milliseconds
104166.66 requests per second
====== SPOP ======
20000 requests completed in 0.20 seconds
100 parallel clients
3 bytes payload
keep alive: 1
88.32% <= 1 milliseconds
100.00% <= 2 milliseconds
100.00% <= 2 milliseconds
102040.82 requests per second
====== LPUSH (needed to benchmark LRANGE) ======
20000 requests completed in 0.19 seconds
100 parallel clients
3 bytes payload
keep alive: 1
91.89% <= 1 milliseconds
99.57% <= 2 milliseconds
100.00% <= 2 milliseconds
105263.16 requests per second
====== LRANGE_100 (first 100 elements) ======
20000 requests completed in 0.74 seconds
100 parallel clients
3 bytes payload
keep alive: 1
0.01% <= 1 milliseconds
70.57% <= 2 milliseconds
99.56% <= 3 milliseconds
99.89% <= 4 milliseconds
100.00% <= 4 milliseconds
26954.18 requests per second
====== LRANGE_300 (first 300 elements) ======
20000 requests completed in 1.97 seconds
100 parallel clients
3 bytes payload
keep alive: 1
0.00% <= 1 milliseconds
0.06% <= 2 milliseconds
2.81% <= 3 milliseconds
23.94% <= 4 milliseconds
54.51% <= 5 milliseconds
84.29% <= 6 milliseconds
96.56% <= 7 milliseconds
98.76% <= 8 milliseconds
99.46% <= 9 milliseconds
99.77% <= 10 milliseconds
99.86% <= 11 milliseconds
99.96% <= 12 milliseconds
100.00% <= 12 milliseconds
10162.60 requests per second
====== LRANGE_500 (first 450 elements) ======
20000 requests completed in 2.92 seconds
100 parallel clients
3 bytes payload
keep alive: 1
0.02% <= 1 milliseconds
0.06% <= 2 milliseconds
0.12% <= 3 milliseconds
0.38% <= 4 milliseconds
9.48% <= 5 milliseconds
28.08% <= 6 milliseconds
47.22% <= 7 milliseconds
65.74% <= 8 milliseconds
81.12% <= 9 milliseconds
91.18% <= 10 milliseconds
97.42% <= 11 milliseconds
99.47% <= 12 milliseconds
99.75% <= 13 milliseconds
99.88% <= 14 milliseconds
99.97% <= 15 milliseconds
100.00% <= 15 milliseconds
6837.61 requests per second
====== LRANGE_600 (first 600 elements) ======
20000 requests completed in 3.61 seconds
100 parallel clients
3 bytes payload
keep alive: 1
0.01% <= 1 milliseconds
0.06% <= 2 milliseconds
0.14% <= 3 milliseconds
0.75% <= 4 milliseconds
7.08% <= 5 milliseconds
18.12% <= 6 milliseconds
29.30% <= 7 milliseconds
40.19% <= 8 milliseconds
51.35% <= 9 milliseconds
62.12% <= 10 milliseconds
73.46% <= 11 milliseconds
85.25% <= 12 milliseconds
92.68% <= 13 milliseconds
96.00% <= 14 milliseconds
98.18% <= 15 milliseconds
99.06% <= 16 milliseconds
99.35% <= 17 milliseconds
99.40% <= 18 milliseconds
99.45% <= 19 milliseconds
99.48% <= 20 milliseconds
99.50% <= 22 milliseconds
99.50% <= 42 milliseconds
99.51% <= 43 milliseconds
99.52% <= 46 milliseconds
99.54% <= 47 milliseconds
99.56% <= 48 milliseconds
99.59% <= 49 milliseconds
99.62% <= 50 milliseconds
99.64% <= 51 milliseconds
99.68% <= 52 milliseconds
99.71% <= 53 milliseconds
99.74% <= 54 milliseconds
99.76% <= 55 milliseconds
99.79% <= 56 milliseconds
99.82% <= 57 milliseconds
99.84% <= 58 milliseconds
99.89% <= 59 milliseconds
99.95% <= 60 milliseconds
99.99% <= 61 milliseconds
100.00% <= 61 milliseconds
5534.03 requests per second
====== MSET (10 keys) ======
20000 requests completed in 0.40 seconds
100 parallel clients
3 bytes payload
keep alive: 1
0.19% <= 1 milliseconds
67.25% <= 2 milliseconds
98.31% <= 3 milliseconds
99.99% <= 4 milliseconds
100.00% <= 4 milliseconds
49627.79 requests per second
JeandeMBP:bin healerjean$
3、 -q 仅显示上面出现结果的request per second的信息
表示每秒请求多少次
healerjean$ redis-benchmark -c 100 -n 20000 -q
PING_INLINE: 107526.88 requests per second
PING_BULK: 98039.22 requests per second
SET: 101522.84 requests per second
GET: 104712.04 requests per second
INCR: 103092.78 requests per second
LPUSH: 102564.11 requests per second
RPUSH: 108108.11 requests per second
LPOP: 103092.78 requests per second
RPOP: 103092.78 requests per second
SADD: 108108.11 requests per second
HSET: 103626.94 requests per second
SPOP: 99502.48 requests per second
LPUSH (needed to benchmark LRANGE): 109289.62 requests per second
LRANGE_100 (first 100 elements): 27137.04 requests per second
LRANGE_300 (first 300 elements): 11210.76 requests per second
LRANGE_500 (first 450 elements): 7830.85 requests per second
LRANGE_600 (first 600 elements): 5927.68 requests per second
MSET (10 keys): 56022.41 requests per second
JeandeMBP:bin healerjean$
4、-t 对指定命令进行基准测试
healerjean$ redis-benchmark -t set,get -q
SET: 109170.30 requests per second
GET: 112612.61 requests per second
JeandeMBP:bin healerjean$
5、–csv 将结果按照csv格式输出,便于后续处理,如导出到excel中
JeandeMBP:bin healerjean$ redis-benchmark -t set,get --csv
"SET","105042.02"
"GET","105263.16"
JeandeMBP:bin healerjean$
3、Pipeline 不是原子性的
1、Pipeline 出现
Redis客户端执行一条没拿过来分为如下4个过程,发送命令,命令排队,执行命令,返回结果,其中1+4成为Round Trip Time (RTT,往返时间)
1、Redis批量操作命令有效节省时间,这种批量命令相当于是原子性,比较节约RTT,但是大部分命令是不支持批量操作的,如果客户端和服务端在一台机器上还好,假如服务器在北京客户端在上海,那就有点麻烦了,传播速度非常慢,
2、为了解决这一的问题,PipeLine流水线机制就出现了,它能将一组RTT传输给Redis,再将这组命令的结果按照顺序返回给客户端,但是它不是原子性的
2、性能测试
在不同网络环境下,pipelin执行速度一般比逐条执行要快,客户端和服务端的网络延迟越大,Pipeline越明显
网络 | 延迟 | 非Pipeline | Pipeline |
---|---|---|---|
本机 | 0.17ms | 573ms | 134ms |
内网服务器 | 0.41ms | 1610ms | 240ms |
异地机房 | 7ms | 78499ms | 1104ms |
虽然Pipeline好用,但是每次组装还需要节制,否则一次组装的数据量过大,一方面会增加客户端的等待时间,另一方面会造成一定的网络阻塞。
4、事物与Lua
即使有多个命令,就会遇到事物的问题。multi和exec这两个命令,一个代表事物开始,一个代表事物结束
redis是不支持回滚的特性,只要语法没有问题,中间即使有的命令报错,其他的命令也一定会执行
除非
举例:社交网站上用户A关注了用户B,那么需要再用户A的关注表中添加用户B,用户B的表中添加粉丝A 这是两个操作,只能同时失败或者成功
客户端1
127.0.0.1:6379> multi
OK
127.0.0.1:6379> sadd user:A:flow user:B
QUEUED
127.0.0.1:6379> sadd user:B:fans user:A
QUEUED
客户端2
这个时候,如果其他客户端执行查找命令,则会提示在队列中,不能查找成功
127.0.0.1:6379> sismember user:A:flow user:B
QUEUED
127.0.0.1:6379> smembers user:A:flow
QUEUED
127.0.0.1:6379>
客户端1
只有执行exec 上面两条命令才能执行成功
127.0.0.1:6379> exec
1) (integer) 1
2) (integer) 1
127.0.0.1:6379>
1、解决事物中出现的错误
1、命令错误
假如说事物中间命令出现语法错误,事物exec也不能正常执行
127.0.0.1:6379> smembers user:A:flow user:B
(error) ERR wrong number of arguments for 'smembers' command
127.0.0.1:6379> smembers user:A:flow
QUEUED
127.0.0.1:6379> exec
(error) EXECABORT Transaction discarded because of previous errors.
127.0.0.1:6379> MULTI
2、运行时错误
就是说由于我们程序员自己的问题导致的,这样即使有事物,也不会回滚的,也都会执行,因为没有语法错误
针对这个问题:有些应用场景需要再执行事物之前,需要确保事物中的key没有被其他客户端修改过,才执行事物,否则不执行,Redis提供了watch命令来解决这个问题
客户端1
127.0.0.1:6379> set key "healerjean"
OK
127.0.0.1:6379> watch key
OK
127.0.0.1:6379> multi
客户端2
127.0.0.1:6379> set key "zhangyj"
OK
客户端1 (下面这个在提交的时候已经被修改了,所以执行事物的记过是nil)
127.0.0.1:6379> append key is-good-man
QUEUED
127.0.0.1:6379> exec
(nil)
5、发布订阅
Redis提供了基于发布/订阅的消息机制,此种模式下,消息发布者和订阅中不能相互直接通信,发布者客户端向指定的频道(channel)发布消息,订阅该频道的每个客户端都可以收到该消息
1、发布消息
publish channel message
发布客户端
下面在频道channel:student 发布了一条消息,返回值为订阅者个数,此时没有订阅者,返回为0
127.0.0.1:6379> publish channel:student "teacher coming"
(integer) 0
127.0.0.1:6379>
2、订阅消息
subscribe channel
订阅客户端
subscribe channel:student
Reading messages... (press Ctrl-C to quit)
1) "subscribe"
2) "channel:student"
3) (integer) 1
…… 这里在等待接收下次
这个时候,发布客户端发布一条消息,
127.0.0.1:6379> publish channel:student "gime start"
(integer) 1
127.0.0.1:6379>
订阅客户端如下
127.0.0.1:6379> subscribe channel:student
Reading messages... (press Ctrl-C to quit)
1) "subscribe"
2) "channel:student"
3) (integer) 1
1) "message"
2) "channel:student"
3) "gime start"
注意事项
1、当订阅的通道的时候,会进入订阅状态,一直等待消息接收,只能接收命令为subscribe ,psubscribe ,unsubscribe,punsubscribe
2、新开启的订阅,无法接收以前的消息,因为redis不会对之前的消息进行持久化
3、取消订阅
unsubscribe channel:student
4、按照匹配模式订阅和曲线订阅
punsubscribe hello*
psubscribe hello*
5、查询订阅
1、查看活跃的频道
所谓活跃的频道是指至少有一个频道被订阅,如果没有的被定义则返回0
pubsub channels [partten]
6379> pubsub channels
1) "channel:student"
127.0.0.1:6379>
没有客户端订阅频道
127.0.0.1:6379> pubsub channels
(empty list or set)
2、查看频道订阅数
127.0.0.1:6379> pubsub numsub channel:student
1) "channel:student"
2) (integer) 1
127.0.0.1:6379>
查看模式的订阅数
127.0.0.1:6379>pubsub numpat
(integer) 1
6、使用场景
聊天教、公告牌
6、GEO (地理信息定位)
支持存储地理位置信息来实现比如地理位置,摇一摇等依赖于地理位置信息的孤男寡女,对于实现这些功能的开发者来说绝对是一个福音
1、增加地理位置信息
添加背景的地理位置信息
geoadd key 经度 纬度 城市
返回结果表示成功的个数,如果已经存在则返回0 ,
127.0.0.1:6379> geoadd cities:location 116.28 39.55 beijing
(integer) 1
127.0.0.1:6379> geoadd cities:location 116.28 39.550 beijing
(integer) 0
127.0.0.1:6379>
同时添加多个地理位置信息
127.0.0.1:6379> geoadd cities:location 116.28 39 beijing 11.78 44.5 shanghai
(integer) 1
127.0.0.1:6379>
2、获取地理位置信息
127.0.0.1:6379> geopos cities:location beijing
1) 1) "116.28000229597091675"
2) "38.99999918434559731"
127.0.0.1:6379>
3、获取两个地理位置之间的距离
geodist key city1 city2 [unit] m米 km千米 mi英里 ft 尺
127.0.0.1:6379> geodist cities:location beijing shanghai
"8053178.4504"
127.0.0.1:6379>
4、获取指定位置范围内的地理信息位置集合
这个有两个命令,一个给出成员goeradiusbymembe,一个给出经纬度georadius
georadiusbymember cities:location beijing 60000km
5、删除地理信息
这里需要知道的是这里存放的数据类型为zset
127.0.0.1:6379> type cities:location
zset
127.0.0.1:6379>
删除
zrem cities:location beijing
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