Node.js MySQL の「接続が失われました: サーバーが接続を閉じました」エラーを解決する方法?

var db_config = {
  host: 'localhost',
  user: 'root',
  password: '',
  database: 'example'
};

var connection;

function handleDisconnect() {
  connection = mysql.createConnection(db_config); 
  connection.connect(function(err) { 
    if(err) { 
      console.log('error when connecting to db:', err);
      setTimeout(handleDisconnect, 2000); 
    } 
  }); 
  connection.on('error', function(err) {
    console.log('db error', err);
    if(err.code === 'PROTOCOL_CONNECTION_LOST') { 
      handleDisconnect(); 
    } else { 
      throw err; 
    }
  });
}

handleDisconnect();

connection.connect(function(err) {
  if (err) {
    console.log("Error connecting to KFC: " + err);
  } else {
    console.log("KF connected!");
  }
});

connection.on('error', function(err) {
  if (err.code === 'PROTOCOL_CONNECTION_LOST') {
    console.log("KF connection lost. Reconnecting...");
    handleKFDisconnect();
  } else {
    throw err;
  }
});