问题是 Mongoose 在以下情况下失去连接​​:

1. Node App 已启动，一切正常(可访问数据库等)
2. 本地运行的 Mongo 服务器进程(版本 2.6.10)停止，然后在 15 秒后启动，一切似乎都很好(可访问数据库等)
3. Mongo 进程已停止。
4. 已发出对 Express 的请求，试图转到数据库(使用 Mongoose)——如预期的那样无法访问。
5. Mongo 进程启动。
6. 发出相同的请求，即使 Mongo 已启动，也无法访问数据库。

如果我重新启动 Node JS 应用程序，一切正常。

为什么对 Mongo 的失败查询(使用 Mongoose 版本 4.4.5)会阻止在数据库进程再次启动时恢复连接？

我们是否应该实现重试机制来尝试恢复连接，直到数据库变得可访问？

我试过提到的配置 here但它没有用。

如有任何帮助，我们将不胜感激。

下面是我们连接助手的示例代码:

'use strict';

const _ = require('lodash');
const mongoose = require('mongoose');
const config = require('../config');
const logger = require('../logger');

const _instance = Symbol('instance');
const _enforcer = Symbol('enforcer');
const _members = Symbol('members');

/**
 * Singleton implementation of ConnectionHelper module
 * This module is responsible to reusing common db connections in the application

 * @type {ConnectionsHelper}
 */
module.exports = class ConnectionsHelper {
  constructor(enforcer) {
    if (enforcer !== _enforcer) {
      throw new Error('invalid singleton instantiation');
    }
    initConnectionFromConfig.call(this);
  }

  /**
   * The single instance
   * @returns {*}
     */
  static get instance() {
    if (!this[_instance]) {
      this[_instance] = new ConnectionsHelper(_enforcer);
    }
    return this[_instance];
  }

  /**
   * method retrieves connection by its name
   * @param connectionKey
   * @returns {*}
   */
  getConnection(connectionKey) {
    return this[_members][connectionKey];
  }

  /**
   * method disconnects all underlying connections
   * @returns {void|MongooseThenable}
   */
  closeConnections() {
    return mongoose.disconnect();
  }
};

function initConnectionFromConfig() {
  this[_members] = {};
  const dbsConnections = config.get('dbsConnections');

  _.forEach(dbsConnections, (connection, connectionName) => {

    const protocol = connection.protocol;
    const repSetPath = connection.mongoPath.join(',');
    const options = connection.options;

    options.server = {auto_reconnect: true, socketOptions: {keepAlive: 1, connectTimeoutMS: 30000 }};
    options.replset = {socketOptions: {keepAlive: 1, connectTimeoutMS: 30000 }};

    this[_members][connectionName] = mongoose.createConnection(protocol + repSetPath, options);

    addConnectionEvents.call(this, connectionName);
  });
}

function initConnectionIfNeeded() {
  this[_members] = {};
  const dbsConnections = config.get('dbsConnections');

  _.forEach(dbsConnections, (connection, connectionName) => {
    const protocol = connection.protocol;
    const repSetPath = connection.mongoPath.join(',');
    const options = connection.options;
    //options.server = {auto_reconnect: true, socketOptions: {keepAlive: 1, connectTimeoutMS: 30000 }};
    //options.replset = {socketOptions: {keepAlive: 1, connectTimeoutMS: 30000 }};

    this[_members][connectionName] = mongoose.createConnection(protocol + repSetPath, options);
    addConnectionEvents.call(this, connectionName);
  });
}

function addConnectionEvents(connectionName) {
  const connection = this[_members][connectionName];

  connection.on('connected', () => {
    logger.debug(`Mongoose connection open`);
  });
  connection.on('error', (err) => {
    logger.debug(`Mongoose connection error: ${err}`);
  });
  connection.on('exception', (err) => {
    logger.debug(`Mongoose connection exception: ${err}`);
  });
  connection.on('disconnected', () => {
    logger.debug(`Mongoose connection disconnected`);
  });
  connection.on('reconnected', () => {
    logger.debug(`Mongoose connection reconnected`);
  });
  connection.on('open', () => {
    logger.debug(`Mongoose connection is open`);
  });
  // If the Node process ends, close the Mongoose connection
  process.on('SIGINT', () => {
    connection.close(() => {
      logger.debug(`Mongoose default connection disconnected through app termination`);
      process.exit(0);
    });
  });
}

最佳答案

我遇到了同样的问题。我所做的是在这里重启 Mongoose :

connection.on('disconnected', () => {
    logger.debug(`Mongoose connection disconnected`);
    mongoose.connect(path);
  });

而且我还使用 setTimeout() 以便它每 3 秒尝试一次。

mongoose.connection.on('disconnected', function () {  
  console.log('Mongoose default connection disconnected'); 
  console.log("Trying to reconnect");

  function connect(){
    mongoose.connect(dbPath, function(err){
      if(err) console.log("Error while trying to reconnect to MongoDB");
    });
  }
  setTimeout(connect, 3000);
});

而且我也使用 ForeverJS。

关于node.js - 当数据库再次可访问时，Mongoose 连接不会恢复，我们在Stack Overflow上找到一个类似的问题： https://stackoverflow.com/questions/35739873/