WordPress 如何启用 Memcached 缓存

3. 把下载的：object-cache.php 复制到 wp-content，注意不是 wp-content/plugins/。

根据这部 我把 object-cache.php 放在 wp-content 目录下面之后显示 380行有错误网站打不开

379-396：
foreach ( $buckets as $bucket => $servers) {
$this->mc[$bucket] = new Memcache();
foreach ( $servers as $server ) {
if ( 'unix://' == substr( $server, 0, 7 ) ) {
$node = $server;
$port = 0;
} else {
list ( $node, $port ) = explode(':', $server);
if ( !$port )
$port = ini_get('memcache.default_port');
$port = intval($port);
if ( !$port )
$port = 11211;
}
$this->mc[$bucket]->addServer($node, $port, true, 1, 1, 15, true, array($this, 'failure_callback'));
$this->mc[$bucket]->setCompressThreshold(20000, 0.2);
}
}

380行是 $this->mc[$bucket] = new Memcache(); 显示有错误 请帮忙看看如何解决

Memcached 已经安装并且开启了