MySQLNonTransientConnectionException

我的论坛也是jforum,几个小时没人访问以后，再访问就会出现下面错误：

An error has occurred.

For detailed error information, please see the HTML source code, and contact the forum Administrator.

com.mysql.jdbc.exceptions.jdbc4.MySQLNonTransientConnectionException: Communications link failure

Last packet sent to the server was 0 ms ago.

Query being executed when exception was thrown:

SELECT COUNT(pm.privmsgs_to_userid) AS private_messages, u.* FROM jforum_users u LEFT JOIN jforum_privmsgs pm ON pm.privmsgs_type = 1 AND pm.privmsgs_to_userid = u.user_id WHERE u.user_id = 1 GROUP BY pm.privmsgs_to_userid

我是Tomcat 5.5 + mysql

Thanks!

以下是右键察看源文件的错误信息：



<html>
<head>
<title>Error</title>
</head>
<body>
An error has occurred.For detailed error information, please see the HTML source code, and contact the forum Administrator.<pre class="pre-error">com.mysql.jdbc.exceptions.jdbc4.MySQLNonTransientConnectionException: Communications link failure

Last packet sent to the server was 1 ms ago.

Query being executed when exception was thrown:

SELECT COUNT(pm.privmsgs_to_userid) AS private_messages, u.* FROM jforum_users u LEFT JOIN jforum_privmsgs pm ON pm.privmsgs_type = 1 AND pm.privmsgs_to_userid = u.user_id WHERE u.user_id = 1 GROUP BY pm.privmsgs_to_userid</pre>
</body>
</html>

您提到的SQL是UserModel.selectById，在generic_queries.sql裡面的內容如下：


UserModel.selectById = SELECT COUNT(pm.privmsgs_to_userid) AS private_messages, u.* \

        FROM jforum_users u \

        LEFT JOIN jforum_privmsgs pm ON pm.privmsgs_type = 1 AND pm.privmsgs_to_userid = u.user_id \

        WHERE u.user_id = ? \

        GROUP BY pm.privmsgs_to_userid

其中user_id = 1時表示使用者為訪客（anonymous)，這個錯誤可能是Session Timeout或Connection Timeout時，系統關閉資料庫連線，造成查詢使用者資料的這個查詢無法執行成功，應該對系統沒有太嚴重的影響，可以不予理會。

參考資料：
http://bugs.mysql.com/bug.php?id=35353