Web项目提升访问性能，使用Memcache做缓存是一种比较通用的方案，这篇文章记录了：动态查看应用如何使用Memcache。 这里使用的Django项目做例子。关于Django如何连接Memcache请查阅官方文档。下面开始：
- “显式”运行Memcache:
<pre> memcached -vv -u root -m 256m </pre>
如果你使用的是root用户，则一定要加上 -u root选项。 命令执行后会得到如下输出：
<pre> slab class 1: chunk size 96 perslab 10922 slab class 2: chunk size 120 perslab 8738 slab class 3: chunk size 152 perslab 6898 slab class 4: chunk size 192 perslab 5461 slab class 5: chunk size 240 perslab 4369 slab class 6: chunk size 304 perslab 3449 slab class 7: chunk size 384 perslab 2730 slab class 8: chunk size 480 perslab 2184 slab class 9: chunk size 600 perslab 1747 slab class 10: chunk size 752 perslab 1394 slab class 11: chunk size 944 perslab 1110 slab class 12: chunk size 1184 perslab 885 slab class 13: chunk size 1480 perslab 708 slab class 14: chunk size 1856 perslab 564 slab class 15: chunk size 2320 perslab 451 slab class 16: chunk size 2904 perslab 361 slab class 17: chunk size 3632 perslab 288 slab class 18: chunk size 4544 perslab 230 slab class 19: chunk size 5680 perslab 184 slab class 20: chunk size 7104 perslab 147 slab class 21: chunk size 8880 perslab 118 slab class 22: chunk size 11104 perslab 94 slab class 23: chunk size 13880 perslab 75 slab class 24: chunk size 17352 perslab 60 slab class 25: chunk size 21696 perslab 48 slab class 26: chunk size 27120 perslab 38 slab class 27: chunk size 33904 perslab 30 slab class 28: chunk size 42384 perslab 24 slab class 29: chunk size 52984 perslab 19 slab class 30: chunk size 66232 perslab 15 slab class 31: chunk size 82792 perslab 12 slab class 32: chunk size 103496 perslab 10 slab class 33: chunk size 129376 perslab 8 slab class 34: chunk size 161720 perslab 6 slab class 35: chunk size 202152 perslab 5 slab class 36: chunk size 252696 perslab 4 slab class 37: chunk size 315872 perslab 3 slab class 38: chunk size 394840 perslab 2 slab class 39: chunk size 493552 perslab 2 slab class 40: chunk size 616944 perslab 1 slab class 41: chunk size 771184 perslab 1 slab class 42: chunk size 1048576 perslab 1 <26 server listening (auto-negotiate) <27 server listening (auto-negotiate) <28 send buffer was 212992, now 268435456 <29 send buffer was 212992, now 268435456 <28 server listening (udp) <28 server listening (udp) <29 server listening (udp) <28 server listening (udp) <29 server listening (udp) <29 server listening (udp) <28 server listening (udp) <29 server listening (udp) </pre>
- 访问应用，这里是刷新下页面 Memcache的输出：
<pre> <30 new auto-negotiating client connection 30: Client using the ascii protocol <30 get :1:views.decorators.cache.cache_header..9d09a91f1b32ac17d49837bcbbef9427.zh-cn.Asia/Shanghai >30 END <30 set :1:views.decorators.cache.cache_header..9d09a91f1b32ac17d49837bcbbef9427.zh-cn.Asia/Shanghai 1 900 6 >30 STORED <30 set :1:views.decorators.cache.cache_page..GET.9d09a91f1b32ac17d49837bcbbef9427.d41d8cd98f00b204e9800998ecf8427e.zh-cn.Asia/Shanghai 1 900 66649 >30 STORED <30 connection closed. </pre>
可以看到应用尝试获取某条缓存，没有找到，便将该key-value存下来，还有缓存多长时间，存储大小等参数。
- 再次刷新页面 Memcache输出：
<pre> <30 new auto-negotiating client connection 30: Client using the ascii protocol <30 get :1:views.decorators.cache.cache_header..9d09a91f1b32ac17d49837bcbbef9427.zh-cn.Asia/Shanghai >30 sending key :1:views.decorators.cache.cache_header..9d09a91f1b32ac17d49837bcbbef9427.zh-cn.Asia/Shanghai >30 END <30 get :1:views.decorators.cache.cache_page..GET.9d09a91f1b32ac17d49837bcbbef9427.d41d8cd98f00b204e9800998ecf8427e.zh-cn.Asia/Shanghai >30 sending key :1:views.decorators.cache.cache_page..GET.9d09a91f1b32ac17d49837bcbbef9427.d41d8cd98f00b204e9800998ecf8427e.zh-cn.Asia/Shanghai >30 END <30 connection closed. </pre>
取了两次，都拿到了。
- 查看Memcache中缓存数据的详细信息
<pre> telnet 127.0.0.1 11211 </pre>
<pre> stats items STAT items:4:number 1 STAT items:4:age 1056 STAT items:4:evicted 0 STAT items:4:evicted_nonzero 0 STAT items:4:evicted_time 0 STAT items:4:outofmemory 0 STAT items:4:tailrepairs 0 STAT items:4:reclaimed 0 STAT items:4:expired_unfetched 0 STAT items:4:evicted_unfetched 0 STAT items:31:number 1 STAT items:31:age 1056 STAT items:31:evicted 0 STAT items:31:evicted_nonzero 0 STAT items:31:evicted_time 0 STAT items:31:outofmemory 0 STAT items:31:tailrepairs 0 STAT items:31:reclaimed 0 STAT items:31:expired_unfetched 0 STAT items:31:evicted_unfetched 0 END </pre>
查看具体item：
<pre> stats cachedump 4 0 ITEM :1:views.decorators.cache.cache_header..9d09a91f1b32ac17d49837bcbbef9427.zh-cn.Asia/Shanghai [6 b; 1405480402 s] END </pre>
这便是刚才保存的数据。 获取某条缓存
<pre> get :1:views.decorators.cache.cache_page..GET.d1537bd0b66a4289001629ac2e06e742.d41d8cd98f00b204e9800998ecf8427e.zh-cn.Asia/Shanghai </pre>
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