一、需求描述
一linode xen vps 1G RAM，40+sites，IO频繁，openfiles ulimit已65535
US时间访问量大增,nginx不定时502
二、解决办法
pages cache化,但这一台vps内存不够用，于是把闲置的几台服务器都装上memcached做缓存集群
再根据网络延迟设定权重
memcached server官方: http://memcached.org/
三、代码
访问memcached server需要php支持，可以选择memcached库和memcache库，注意2者名字的区别
详细对比：https://code.google.com/p/memcached/wiki/PHPClientComparison
我采用的是php memcache: http://php.net/manual/en/book.memcache.php 因为memcache不依赖libmemcached
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//集群数组$memserver = array ( array ( 'host' => 'fast1.xxx.com' , 'port' => 13579 , 'weight' => 40 ), array ( 'host' => 'fast2.xxx.com' , 'port' => 13579 , 'weight' => 20 ), array ( 'host' => 'fast3.xxx.com' , 'port' => 13579 , 'weight' => 20 ), array ( 'host' => 'slow1.xxx.com' , 'port' => 24680 , 'weight' => 5 ), array ( 'host' => 'slow2.xxx.com' , 'port' => 24680 , 'weight' => 5 ), array ( 'host' => 'local.xxx.com' , 'port' => 11211 , 'weight' => 10 )); |
键值读、写、删就没什么说的了直接按文档sample写即可
考虑到以后的移植问题，记得首先检测环境是否支持memcache: class_exists(‘Memcache’)
下面是我的实现，因为特定需求，几个函数写的相对独立，memcache也没做全局实例化。
你可以根据自己需求把memcache在全局实例化，优化操作。
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//---get content from memcache---
function
getCache(
$key
)
{
Global
$memserver
;
$ret
= false;
$key
= md5(
$key
);
$mc
=
new
Memcache();
foreach
(
$memserver
as
$s
)
$mc
->addServer(
$s
[
'host'
],
$s
[
'port'
], FALSE,
$s
[
'weight'
] );
$ret
=
$mc
->get(
$key
);
$mc
->close();
unset(
$mc
);
return
$ret
;
}
//---set content from memcache---
function
setCache(
$key
,
$val
)
{
Global
$memserver
;
$ret
= false;
$key
= md5(
$key
);
$mc
=
new
Memcache();
foreach
(
$memserver
as
$s
)
$mc
->addServer(
$s
[
'host'
],
$s
[
'port'
], FALSE,
$s
[
'weight'
] );
if
( isset(
$val
[
'cached'
]) )
{
$val
[
'cached'
] = 1;
$ret
=
$mc
->set(
$key
,
$val
);
}
$mc
->close();
unset(
$mc
);
return
$ret
;
}
//---delete content from memcache---
function
delCache(
$key
)
{
Global
$memserver
;
$ret
= false;
$key
= md5(
$key
);
$mc
=
new
Memcache();
foreach
(
$memserver
as
$s
)
$mc
->addServer(
$s
[
'host'
],
$s
[
'port'
], FALSE,
$s
[
'weight'
] );
$ret
=
$mc
->
delete
(
$key
, 0);
$mc
->close();
unset(
$mc
);
return
$ret
;
}
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