有次同事提出開(kāi)發(fā)使用的MySQL數(shù)據(jù)庫(kù)連接很慢，因?yàn)槲覀兊腗ySQL開(kāi)發(fā)數(shù)據(jù)庫(kù)是單獨(dú)一臺(tái)機(jī)器部署的，所以認(rèn)為可能是網(wǎng)絡(luò)連接問(wèn)題導(dǎo)致的。

在進(jìn)行 ping和route后發(fā)現(xiàn)網(wǎng)絡(luò)通信都是正常的，而且在MySQL機(jī)器上進(jìn)行本地連接發(fā)現(xiàn)是很快的，所以網(wǎng)絡(luò)問(wèn)題基本上被排除了。以前也遇到過(guò)一次這樣的問(wèn)題，可后來(lái)就不知怎么突然好了，這次又遭遇這樣的問(wèn)題，所以想看看是不是MySQL的配置問(wèn)題。在查詢MySQL相關(guān)文檔和網(wǎng)絡(luò)搜索后，發(fā)現(xiàn)了一個(gè)配置似乎可以解決這樣的問(wèn)題，就是在MySQL的配置文件中增加如下配置參數(shù)：

[mysqld]skip-name-resolve

在Linux下配置文件是/etc/my.cnf，在windows下配置文件是MySQL安裝目錄下的my.ini文件。注意該配置是加在 [mysqld]下面，在更改配置并保存后，然后重啟mysql并遠(yuǎn)程連接測(cè)試，一切恢復(fù)如初。該參數(shù)的官方解釋信息如下：

復(fù)制代碼 代碼如下:How MySQL uses DNS

When a new thread connects to mysqld, mysqld will spawn a new thread to handle the request. This thread will first check if the hostname is in the hostname cache. If not the thread will call gethostbyaddr_r() and gethostbyname_r() to resolve the hostname.

If the operating system doesn't support the above thread-safe calls, the thread will lock a mutex and call gethostbyaddr() and gethostbyname() instead. Note that in this case no other thread can resolve other hostnames that is not in the hostname cache until the first thread is ready.

You can disable DNS host lookup by starting mysqld with