Memcached的使用
1. Memcached简介
-
Memcached是一个开源的,高性能,分布式内存对象缓存系统。
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Memcached是一种基于内存的key-value存储,用来存储小块的任意数据(字符串、对象)。这些数据可以是数据库调用、API调用或者是页面渲染的结果。
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一般的使用目的是,通过缓存数据库查询结果,减少数据库访问次数,以提高动态Web应用的速度、提高可扩展性。
1.1. 特征
memcached作为高速运行的分布式缓存服务器,具有以下的特点。
- 协议简单
- 基于libevent的事件处理
- 内置内存存储方式
- memcached不互相通信的分布式
2. 安装与运行
2.1. 自动安装
# For Redhat/Fedora
yum install -y memcached
# For Debian or Ubuntu
apt-get install memcached
2.2. 源码安装
安装指定版本的Memcached可以从 https://github.com/memcached/memcached/wiki/ReleaseNotes 地址下载。
# Memcached depends on libevent
yum install libevent-devel
# install
wget https://memcached.org/latest
[you might need to rename the file]
tar -zxf memcached-1.x.x.tar.gz
cd memcached-1.x.x
./configure --prefix=/usr/local/memcached
make && make test && sudo make install
问题
如遇以下报错,可再执行make install
。
Signal handled: Interrupt.
ok 51 - shutdown
ok 52 - stop_server
/bin/sh:行3: prove: 未找到命令
make: *** [test] Error 127
2.3. 验证
确认是否安装成功,可执行以下命令
/usr/local/memcached/bin/memcached -h
2.4. 运行
2.4.1. 前台运行
/usr/local/memcached/bin/memcached -p 11211 -m 64m -vv
2.4.2. 后台运行
/usr/local/memcached/bin/memcached -p 11211 -m 64m -d -c 102400 -t 8 -P /tmp/memcached.pid
2.5. 连接
$ telnet 127.0.0.1 11211
Trying 127.0.0.1...
Connected to 127.0.0.1.
Escape character is '^]'.
set foo 0 0 3 保存命令
bar 数据
STORED 结果
get foo 取得命令
VALUE foo 0 3 数据
bar 数据
END 结束行
quit 退出
3. Memcached运行参数
# /usr/local/memcached/bin/memcached -h
memcached 1.5.12
-p, --port=<num> TCP port to listen on (default: 11211)
-U, --udp-port=<num> UDP port to listen on (default: 0, off)
-s, --unix-socket=<file> UNIX socket to listen on (disables network support)
-A, --enable-shutdown enable ascii "shutdown" command
-a, --unix-mask=<mask> access mask for UNIX socket, in octal (default: 0700)
-l, --listen=<addr> interface to listen on (default: INADDR_ANY)
-d, --daemon run as a daemon
-r, --enable-coredumps maximize core file limit
-u, --user=<user> assume identity of <username> (only when run as root)
-m, --memory-limit=<num> item memory in megabytes (default: 64 MB)
-M, --disable-evictions return error on memory exhausted instead of evicting
-c, --conn-limit=<num> max simultaneous connections (default: 1024)
-k, --lock-memory lock down all paged memory
-v, --verbose verbose (print errors/warnings while in event loop)
-vv very verbose (also print client commands/responses)
-vvv extremely verbose (internal state transitions)
-h, --help print this help and exit
-i, --license print memcached and libevent license
-V, --version print version and exit
-P, --pidfile=<file> save PID in <file>, only used with -d option
-f, --slab-growth-factor=<num> chunk size growth factor (default: 1.25)
-n, --slab-min-size=<bytes> min space used for key+value+flags (default: 48)
-L, --enable-largepages try to use large memory pages (if available)
-D <char> Use <char> as the delimiter between key prefixes and IDs.
This is used for per-prefix stats reporting. The default is
":" (colon). If this option is specified, stats collection
is turned on automatically; if not, then it may be turned on
by sending the "stats detail on" command to the server.
-t, --threads=<num> number of threads to use (default: 4)
-R, --max-reqs-per-event maximum number of requests per event, limits the
requests processed per connection to prevent
starvation (default: 20)
-C, --disable-cas disable use of CAS
-b, --listen-backlog=<num> set the backlog queue limit (default: 1024)
-B, --protocol=<name> protocol - one of ascii, binary, or auto (default)
-I, --max-item-size=<num> adjusts max item size
(default: 1mb, min: 1k, max: 128m)
-F, --disable-flush-all disable flush_all command
-X, --disable-dumping disable stats cachedump and lru_crawler metadump
-o, --extended comma separated list of extended options
most options have a 'no_' prefix to disable
- maxconns_fast: immediately close new connections after limit
- hashpower: an integer multiplier for how large the hash
table should be. normally grows at runtime.
set based on "STAT hash_power_level"
- tail_repair_time: time in seconds for how long to wait before
forcefully killing LRU tail item.
disabled by default; very dangerous option.
- hash_algorithm: the hash table algorithm
default is murmur3 hash. options: jenkins, murmur3
- lru_crawler: enable LRU Crawler background thread
- lru_crawler_sleep: microseconds to sleep between items
default is 100.
- lru_crawler_tocrawl: max items to crawl per slab per run
default is 0 (unlimited)
- lru_maintainer: enable new LRU system + background thread
- hot_lru_pct: pct of slab memory to reserve for hot lru.
(requires lru_maintainer)
- warm_lru_pct: pct of slab memory to reserve for warm lru.
(requires lru_maintainer)
- hot_max_factor: items idle > cold lru age * drop from hot lru.
- warm_max_factor: items idle > cold lru age * this drop from warm.
- temporary_ttl: TTL's below get separate LRU, can't be evicted.
(requires lru_maintainer)
- idle_timeout: timeout for idle connections
- slab_chunk_max: (EXPERIMENTAL) maximum slab size. use extreme care.
- watcher_logbuf_size: size in kilobytes of per-watcher write buffer.
- worker_logbuf_size: size in kilobytes of per-worker-thread buffer
read by background thread, then written to watchers.
- track_sizes: enable dynamic reports for 'stats sizes' command.
- no_inline_ascii_resp: save up to 24 bytes per item.
small perf hit in ASCII, no perf difference in
binary protocol. speeds up all sets.
- no_hashexpand: disables hash table expansion (dangerous)
- modern: enables options which will be default in future.
currently: nothing
- no_modern: uses defaults of previous major version (1.4.x)
常用参数:
- -d是启动一个守护进程;
- -m是分配给Memcache使用的内存数量,单位是MB;
- -u是运行Memcache的用户;
- -l是监听的服务器IP地址,可以有多个地址;
- -p是设置Memcache监听的端口,,最好是1024以上的端口;
- -c是最大运行的并发连接数,默认是1024;
- -t是线程数,默认为4;
- -P是设置保存Memcache的pid文件。
参考文章:
- https://github.com/memcached/memcached/wiki/Overview
- https://github.com/memcached/memcached/wiki/Install
- http://www.runoob.com/memcached/memcached-tutorial.html
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最后修改 December 30, 2022: add linux notes (85fc35b)