memcached简单使用

memcached
database
发布日期:   2017-12-05
文章字数:   1.3k
阅读时长:   6 分

什么是memcached

Memcached 是一个高性能的分布式内存对象缓存系统，用于动态Web应用以减轻数据库负载。它通过在内存中缓存数据和对象来减少读取数据库的次数，从而提高动态、数据库驱动网站的速度。Memcached基于一个存储键/值对的hashmap。其守护进程（daemon ）是用C写的，但是客户端可以用任何语言来编写，并通过memcached协议与守护进程通信。

安装memcached

mac下安装

brew install memcached

查看是否安装成功

jockie:~$ which memcached
/usr/local/bin/memcached
jockie:~$ brew list | grep memcached
memcached

ubuntu下安装

sudo apt-get install memcached

查看是否安装成功

:~$ which memcached 
/usr/bin/memcached

启动memcached

jockie:~$ memcached -d
  • -p 指定占用端口，默认11211
  • -d 让memcached在后台运行
  • -m 指定占用内存，单位为MB,默认64MB
  • -l 如果想要让别的机器连接，就必须设置-l 0.0.0.0

查看服务是否启动

jockie:~$ ps aux | grep memcached
jockie            4980   0.0  0.0  2442020   1992 s001  S+    7:12PM   0:00.00 grep memcached
jockie            4974   0.0  0.0  2480544   2484   ??  Ss    7:12PM   0:00.01 memcached -d

telnet操作memcached

  1. 连接和退出
    连接: telnet ip地址 [11211]
    退出: quit

  2. 基本命令

    • 存储命令

      • 基本语法： 
        command key flags exptime bytes [noreply] 
value
      • 参数说明：
        • command: 存储命令，包含set/add/replace/append/prepend
        • key: 键值 key-value 结构中的 key，用于查找缓存值。
        • flags: 可以包括键值对的整型参数，客户机使用它存储关于键值对的额外信息 。
        • exptime: 在缓存中保存键值对的时间长度（以秒为单位，0 表示永远）。
        • bytes: 在缓存中存储的字节数。
        • noreply(可选): 该参数告知服务器不需要返回数据。
        • value: 存储的值（始终位于第二行)（可直接理解为key-value结构中的value）。
      • 示例： 
        jockie:~$ telnet 127.0.0.1 11211
Trying 127.0.0.1...
Connected to localhost.
Escape character is '^]'.
set username 0 0 4
jack
STORED
add username 0 0 4
john
NOT_STORED
add pass 0 0 6
123456
STORED
replace username 0 0 5
peter
STORED
append username 0 0 5
athon
STORED
prepend pass 0 0 2
00
STORED

    • 查找命令

      • 基本语法 
        command key1 [key2 key3]
      • 参数说明：
        • command: 包含get/gets/delete
      • 示例： 
        get username
VALUE username 0 9
johnathon
END
get username pass
VALUE username 0 9
johnathon
VALUE pass 0 8
00123456
END
delete pass
DELETED
get pass
END

    • 自增自减命令

      • 基本语法： 
        command key value
      • 参数说明：
        • command： 包含incr/decr
        • value: 自增或自减的值
      • 示例： 
        set height 0 0 3
180
STORED
get height
VALUE height 0 3
180
END
incr height 5
185
get height
VALUE height 0 3
185
END
decr height 10
175
get height
VALUE height 0 3
175
END

    • 统计命令

      • stats
        stats
STAT pid 4974
STAT uptime 4990
STAT time 1512477311
STAT version 1.5.3
STAT libevent 2.1.8-stable
STAT pointer_size 64
STAT rusage_user 0.510169
STAT rusage_system 0.355403
STAT max_connections 1024
STAT curr_connections 10
STAT total_connections 20
STAT rejected_connections 0
STAT connection_structures 11
STAT reserved_fds 20
STAT cmd_get 27
STAT cmd_set 19
STAT cmd_flush 6
STAT cmd_touch 0
STAT get_hits 16
STAT get_misses 11
STAT get_expired 0
STAT get_flushed 4
STAT delete_misses 0
STAT delete_hits 2
STAT incr_misses 0
STAT incr_hits 1
STAT decr_misses 0
STAT decr_hits 1
STAT cas_misses 0
STAT cas_hits 0
STAT cas_badval 0
STAT touch_hits 0
STAT touch_misses 0
STAT auth_cmds 0
STAT auth_errors 0
STAT bytes_read 1015
STAT bytes_written 786
STAT limit_maxbytes 67108864
STAT accepting_conns 1
STAT listen_disabled_num 0
STAT time_in_listen_disabled_us 0
STAT threads 4
STAT conn_yields 0
STAT hash_power_level 16
STAT hash_bytes 524288
STAT hash_is_expanding 0
STAT slab_reassign_rescues 0
STAT slab_reassign_chunk_rescues 0
STAT slab_reassign_evictions_nomem 0
STAT slab_reassign_inline_reclaim 0
STAT slab_reassign_busy_items 0
STAT slab_reassign_busy_deletes 0
STAT slab_reassign_running 0
STAT slabs_moved 0
STAT lru_crawler_running 0
STAT lru_crawler_starts 3315
STAT lru_maintainer_juggles 8302
STAT malloc_fails 0
STAT log_worker_dropped 0
STAT log_worker_written 0
STAT log_watcher_skipped 0
STAT log_watcher_sent 0
STAT bytes 144
STAT curr_items 2
STAT total_items 15
STAT slab_global_page_pool 0
STAT expired_unfetched 0
STAT evicted_unfetched 0
STAT evicted_active 0
STAT evictions 0
STAT reclaimed 1
STAT crawler_reclaimed 0
STAT crawler_items_checked 2
STAT lrutail_reflocked 0
STAT moves_to_cold 16
STAT moves_to_warm 5
STAT moves_within_lru 0
STAT direct_reclaims 0
STAT lru_bumps_dropped 0
END
      • stats items
        stats items
STAT items:1:number 2
STAT items:1:number_hot 0
STAT items:1:number_warm 0
STAT items:1:number_cold 2
STAT items:1:age_hot 0
STAT items:1:age_warm 0
STAT items:1:age 705
STAT items:1:evicted 0
STAT items:1:evicted_nonzero 0
STAT items:1:evicted_time 0
STAT items:1:outofmemory 0
STAT items:1:tailrepairs 0
STAT items:1:reclaimed 1
STAT items:1:expired_unfetched 0
STAT items:1:evicted_unfetched 0
STAT items:1:evicted_active 0
STAT items:1:crawler_reclaimed 0
STAT items:1:crawler_items_checked 2
STAT items:1:lrutail_reflocked 0
STAT items:1:moves_to_cold 16
STAT items:1:moves_to_warm 5
STAT items:1:moves_within_lru 0
STAT items:1:direct_reclaims 0
STAT items:1:hits_to_hot 5
STAT items:1:hits_to_warm 0
STAT items:1:hits_to_cold 11
STAT items:1:hits_to_temp 0
END
      • stats slabs
        tats slabs
STAT 1:chunk_size 96
STAT 1:chunks_per_page 10922
STAT 1:total_pages 1
STAT 1:total_chunks 10922
STAT 1:used_chunks 2
STAT 1:free_chunks 10920
STAT 1:free_chunks_end 0
STAT 1:mem_requested 144
STAT 1:get_hits 16
STAT 1:cmd_set 19
STAT 1:delete_hits 2
STAT 1:incr_hits 1
STAT 1:decr_hits 1
STAT 1:cas_hits 0
STAT 1:cas_badval 0
STAT 1:touch_hits 0
STAT active_slabs 1
STAT total_malloced 1048576
END

    • 清理缓存命令

      • 基本语法：
        flush_all [time] [noreply]
      • 参数说明：
        [time]可选参数，用于在指定时间执行清理缓存操作。
      • 示例：
        flush_all
OK
get username
END
get pass
END

python操作memcached

  1. 安装python-memcached: pip install python-memcached
  2. 连接memcached
    import memcache
mc = memcache.Client(['127.0.0.1:11211'], debug=True)
  3. 设置数据
    mc.set('username', 'john', time=60)
mc.set('count',10,time=60)
mc.set_multi({'gender': 'male', 'phone': '111111'}, time=60 * 2)
  4. 获取数据
    print(mc.get('phone'))
  5. 删除数据
    mc.delete('gender')
  6. 自增、自减
    mc.incr('count') # delta默认值为1
mc.decr('count', delta=3)
文章作者: keepwonder
文章链接: http://xuanxiewu.com/2017/12/05/memcached-jian-dan-shi-yong/
版权声明: 本博客所有文章除特別声明外，均采用 CC BY 4.0 许可协议。转载请注明来源 keepwonder !
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