Redis常用命令解析——INFO, MONITOR, SLOWLOG

  作者：zhanhailiang 日期：2014-12-02

1. INFO

info指令返回服务器相关信息，包括：

• server: General information about the Redis server
• clients: Client connections section
• memory: Memory consumption related information
• persistence: RDB and AOF related information
• stats: General statistics
• replication: Master/slave replication information
• cpu: CPU consumption statistics
• commandstats: Redis command statistics
• cluster: Redis Cluster section
• keyspace: Database related statistics

其本身支持定制返回列表：

[root@~]# redis-cli info
[root@~]# redis-cli info default
[root@~]# redis-cli info all

详情请见：http://www.redis.cn/commands/info.html

2. MONITOR

MONITOR是一个调试命令，返回服务器处理的每一个命令，它能帮助我们了解在数据库上发生了什么操作。共有3种操作方法：

[root@~]# redis-cli monitor
OK
1417532512.619715 [0 127.0.0.1:55043] "REPLCONF" "ACK" "6623624"
[root@~]# telnet 127.0.0.1 6379
Trying 127.0.0.1...
Connected to 127.0.0.1.
Escape character is ‘^]‘.
monitor
+OK
+1417532567.733458 [0 127.0.0.1:55043] "REPLCONF" "ACK" "6623708"
+1417532568.735936 [0 127.0.0.1:55043] "REPLCONF" "ACK" "6623708"
quit
+OK
Connection closed by foreign host.
[root@~]# redis-cli 
127.0.0.1:6379> monitor
OK
1417532590.785487 [0 127.0.0.1:55043] "REPLCONF" "ACK" "6623736"

由于MONITOR命令返回服务器处理的所有的命令, 所以在性能上会有一些消耗。使用官方的压测工具测试结果如下

在不运行MONITOR命令的情况下，benchmark的测试结果:

[root@~/software/redis-2.8.17]# src/redis-benchmark -c 10 -n 100000 -q
PING_INLINE: 51020.41 requests per second
PING_BULK: 50607.29 requests per second
SET: 37257.82 requests per second
GET: 49800.80 requests per second
INCR: 38699.69 requests per second
LPUSH: 38910.51 requests per second
LPOP: 39277.30 requests per second
SADD: 54614.96 requests per second
SPOP: 51948.05 requests per second
LPUSH (needed to benchmark LRANGE): 38819.88 requests per second
LRANGE_100 (first 100 elements): 20112.63 requests per second
LRANGE_300 (first 300 elements): 9025.27 requests per second
LRANGE_500 (first 450 elements): 6836.67 requests per second
LRANGE_600 (first 600 elements): 5406.28 requests per second
MSET (10 keys): 19394.88 requests per second

在运行MONITOR命令的情况下，benchmark的测试结果: (redis-cli monitor > /dev/null):

[root@~/software/redis-2.8.17]# src/redis-benchmark -c 10 -n 100000 -q
PING_INLINE: 42211.91 requests per second
PING_BULK: 42936.88 requests per second
SET: 26143.79 requests per second
GET: 33990.48 requests per second
INCR: 26553.37 requests per second
LPUSH: 27337.34 requests per second
LPOP: 27225.70 requests per second
SADD: 30459.95 requests per second
SPOP: 39494.47 requests per second
LPUSH (needed to benchmark LRANGE): 26315.79 requests per second
LRANGE_100 (first 100 elements): 22055.58 requests per second
LRANGE_300 (first 300 elements): 8104.38 requests per second
LRANGE_500 (first 450 elements): 6371.05 requests per second
LRANGE_600 (first 600 elements): 5031.95 requests per second
MSET (10 keys): 14861.05 requests per second

可以看到各项指标基本都有所下降。

详情请见：http://www.redis.cn/commands/monitor.html

3. SLOWLOG

通过SLOWLOG可以读取慢查询日志。

使用SLOWLOG LEN就可以获取当前慢日志长度。

[root@~/software/redis-2.8.17]# redis-cli 
127.0.0.1:6379> slowlog len
(integer) 28

使用SLOWLOG GET就可以获取所有慢日志。

127.0.0.1:6379> slowlog get 
 1) 1) (integer) 27
    2) (integer) 1417531320
    3) (integer) 24623
    4) 1) "info"

其中，各项指标表示：

• A unique progressive identifier for every slow log entry.
• The unix timestamp at which the logged command was processed.
• The amount of time needed for its execution, in microseconds（注意，microseconds翻译成微秒，而不是毫秒）.
• The array composing the arguments of the command.

使用SLOWLOG GET N就可以获取最近N条慢日志。

127.0.0.1:6379> slowlog get 2
1) 1) (integer) 27
   2) (integer) 1417531320
   3) (integer) 24623
   4) 1) "info"
2) 1) (integer) 26
   2) (integer) 1417528379
   3) (integer) 21363
   4) 1) "get"
      2) "user:score"

使用SLOWLOG RESET命令重置慢日志。一旦执行，将丢失以前的所有慢日志。

127.0.0.1:6379> slowlog reset

详情请见：http://www.redis.cn/commands/slowlog.html