Error: Cannot enqueue Query after fatal error. Expressjs. Mysql

Question

I have my Express js connect to multiple dbs. Which works everytime I startup my app. But As soon as my connection to my database goes stale... the connection returns an error code of PROTOCOL_CONNECTION_LOST. Which is normal for a mysql when a connection is idle. My mysql server is deployed in AWS RDS which also works just fine.

问题是，每次我的 express 应用程序遇到PROTOCOL_CONNECTION_LOST错误时，它都应该重新连接到数据库，这实际上也有效。BUUT 当我尝试对我的 MYSQL 数据库进行查询时。它返回一个Error: Cannot enqueue Query after fatal error.错误。我一直在处理这个问题，我的解决方法是每次都重新启动 express 应用程序。希望其他人遇到过这种情况并可以提供建议。

这是我连接到数据库的示例代码：

var mysql = require('mysql');
var mysqlConn
// mysqlConn.connect();

function handleDisconnect() {
    mysqlConn = mysql.createConnection({
        host: 'aws_instance***',
        user: '******',
        password: '*****',
        database: 'my_db',
        multipleStatements: true
    });

    mysqlConn.connect(function (err) {
        if (err) {
            console.log('ERROR CONNECT admin:', err.code + '--' + err.address);
            setTimeout(handleDisconnect, 2000);
        } else {
            console.log('Connected to DB')
        }
    });

    mysqlConn.on('error', function (err) {
        console.log('ERROR admin', err.code + '--' + err.address);
        if (err.code === 'PROTOCOL_CONNECTION_LOST') {   // Connection to the MySQL server is usually
            console.log("Connection to db lost!")
            handleDisconnect();                         // lost due to either server restart, or a
        } else {    
            console.log(err)                                  // connnection idle timeout (the wait_timeout
            throw err;                                  // server variable configures this)
        }
    });

}

handleDisconnect();
module.exports = {
    mysqlConn: mysqlConn,
};

然后这是我的输出日志，如我的服务器日志中所示。

ERROR db PROTOCOL_CONNECTION_LOST--undefined
Connection to db lost!
Connected to db
OPTIONS /verify-token/ 200 0.285 ms - 4
Error: Cannot enqueue Query after fatal error.
POST /verify-token/ 500 1.332 ms - 95
OPTIONS /auth/login 200 0.793 ms - 4
Error: Cannot enqueue Query after fatal error.
POST /login 500 1.564 ms - 58
OPTIONS /login 200 0.687 ms - 4
Error: Cannot enqueue Query after fatal error.
POST /login 500 1.467 ms - 58

Answer 1

虽然有变通办法，但它们显然并不适用于所有人。文档中的建议是使用连接池而不是手动管理单个连接。