无法在节点中建立持久的mysql连接

我有一个节点mysql连接，过去可以正常工作，但自从流量开始到来，我得到了一个奇怪的错误

Error: Connection lost: The server closed the connection.

这是我正在使用的类

const mysql = require('mysql');

class Database {
constructor() {
    this.connection = mysql.createConnection({
        host: process.env.DB_HOST,
        user: process.env.DB_USERNAME,
        password: process.env.DB_PASSWORD,
        database: process.env.DB_NAME,
        port: 3306,
        debug: false,
        multipleStatements: false
    });
}
query(sql, args) {
    return new Promise((resolve, reject) => {
        this.connection.query(sql, args, (err, rows) => {
            if (err)
                return reject(err);
            resolve(rows);
        });
    });
}
close() {
    return new Promise((resolve, reject) => {
        this.connection.end(err => {
            if (err)
                return reject(err);
            resolve();
        });
    });
 }
}
module.exports = Database;

有人能帮忙解释为什么会发生这种情况吗

编辑：这是我如何调用代码的

const database = new Database();
database.query(`select * from users...
`, [req.user.id, parseInt(req.body.after)])
    .then(rows => {
        appData[".."] = rows['ddd']
        res.status(200).json(appData);
        database.close()
    }, err => {
        return database.close().then(() => { throw err; })
    })
    .catch(err => {
        console.log(err);
        res.status(500).json("Database Error");
    })

---

前一段时间我也遇到了同样的问题，但现在问题还没有发生，也许这个解决方案对你有帮助

var mysql = require('mysql');

var pool = mysql.createPool({
    connectionLimit: 10,
    host: process.env.DB_HOST,
    user: process.env.DB_USERNAME,
    password: process.env.DB_PASSWORD,
    database: process.env.DB_NAME,
    port: 3306,
    debug: false,
    multipleStatements: false
});

module.exports = pool;


exports.executeQuery = function (query, callback) {
    pool.getConnection(function (err, connection) {
        if (err) {
            connection.release();
            throw err;
        }
        connection.query(query, function (err, rows) {
            connection.release();
            if (!err) {
                callback(null, {
                    rows: rows
                });
            }
        });
        connection.on('error', function (err) {
            throw err;
            return;
        });
    });
}

---

首先创建文件ex database.js

var mysql = require('mysql');
var pool = mysql.createPool({
    connectionLimit: 10,
    host: conf_core_sys.dbConfig.host,
    user: conf_core_sys.dbConfig.user,
    dateStrings: true,
    password: conf_core_sys.dbConfig.pass,
    database: conf_core_sys.dbConfig.dbName,
    port:conf_core_sys.dbConfig.port,
    debug: false
});

module.exports = pool;
exports.executeQuery = function (query, callback) {
    pool.getConnection(function (err, connection) {
        if (err) {
            connection.release();
            throw err;
        }
        connection.query(query, function (err, rows) {
            connection.release();
            if (!err) {
                callback(null, {
                    rows: rows
                });
            }
        });
        connection.on('error', function (err) {
            throw err;
            return;
        });
    });
}

第二步：

let database = require("database")
let sql ="SELECT * from users";
database.query(sql, function (error, results, fields) {
    if (error) {
        callback(results)
    } else {
        callback(results)
    }
})

---

你能举一个调用这个函数的代码示例吗？在哪里，如何调用？@Paul添加了调用代码我该如何调用这个函数？你可以先添加你的代码，用ex-database.js保存连接，如果这样做了只需调用函数，让database=requiredatabase=SELECT*from users；database.querysql，函数错误，结果，字段{if error{response.errorsqlerror，函数结果{callbackresults}；}else{callbackresults}