redis监控

redis提供了INFO这个命令，能够随时监控服务器的状态，只用telnet到对应服务器的端口，执行命令即可：

 

[root@cache01 ~]# telnet localhost 6379
Trying ::1...
telnet: connect to address ::1: Connection refused
Trying 127.0.0.1...
Connected to localhost.
Escape character is '^]'.
info
$2290
# Server
redis_version:3.2.1
redis_git_sha1:00000000
redis_git_dirty:0
redis_build_id:c315aa1c1a3951d6
redis_mode:standalone
os:Linux 2.6.32-573.el6.x86_64 x86_64
arch_bits:64
multiplexing_api:epoll
gcc_version:4.4.7
process_id:8936
run_id:49642c08e9bd20589b4650dbb7d1c73873845964
tcp_port:6379
uptime_in_seconds:12687
uptime_in_days:0
hz:10
lru_clock:8237610
executable:/app/server/redis/bin/redis-server
config_file:/app/server/redis/conf/6379.conf

# Clients
connected_clients:3
client_longest_output_list:0
client_biggest_input_buf:0
blocked_clients:0

# Memory
used_memory:1933624
used_memory_human:1.84M
used_memory_rss:3981312
used_memory_rss_human:3.80M
used_memory_peak:1973552
used_memory_peak_human:1.88M
total_system_memory:513724416
total_system_memory_human:489.93M
used_memory_lua:37888
used_memory_lua_human:37.00K
maxmemory:0
maxmemory_human:0B
maxmemory_policy:volatile-lru
mem_fragmentation_ratio:2.06
mem_allocator:jemalloc-4.0.3

# Persistence
loading:0
rdb_changes_since_last_save:0
rdb_bgsave_in_progress:0
rdb_last_save_time:1467851744
rdb_last_bgsave_status:ok
rdb_last_bgsave_time_sec:0
rdb_current_bgsave_time_sec:-1
aof_enabled:0
aof_rewrite_in_progress:0
aof_rewrite_scheduled:0
aof_last_rewrite_time_sec:-1
aof_current_rewrite_time_sec:-1
aof_last_bgrewrite_status:ok
aof_last_write_status:ok

# Stats
total_connections_received:2191
total_commands_processed:32551
instantaneous_ops_per_sec:3
total_net_input_bytes:1559080
total_net_output_bytes:49567278
instantaneous_input_kbps:0.15
instantaneous_output_kbps:1.59
rejected_connections:0
sync_full:2
sync_partial_ok:0
sync_partial_err:0
expired_keys:0
evicted_keys:0
keyspace_hits:164
keyspace_misses:3
pubsub_channels:1
pubsub_patterns:0
latest_fork_usec:246
migrate_cached_sockets:0

# Replication
role:master
connected_slaves:1
slave0:ip=192.168.1.68,port=6379,state=online,offset=885306,lag=1
master_repl_offset:885320
repl_backlog_active:1
repl_backlog_size:1048576
repl_backlog_first_byte_offset:5778
repl_backlog_histlen:879543

# CPU
used_cpu_sys:28.18
used_cpu_user:12.10
used_cpu_sys_children:0.02
used_cpu_user_children:0.00

# Cluster
cluster_enabled:0

# Keyspace
db0:keys=8,expires=0,avg_ttl=0

quit
+OK
==============================================
keyspace_hits:164
keyspace_misses:3
used_memory:1933624
expired_keys:0
evicted_keys:0
上面这几项与缓存的状态有关系；
通过计算hits和miss，我们可以得到缓存的命中率：14414110 / (14414110 + 3228654) = 81% ，一个缓存失效机制，和过期时间设计良好的系统，命中率可以做到95%以上,对于整体性能提升是很大的。

used_memory,expired_keys,evicted_keys这3个信息的具体含义，redis的官方也有一篇很详细的说明： http://redis.io/commands/info