Mongoose.js 通过一次 connect() 调用创建到 MongoDB 的多个连接 [英] Mongoose.js creates multiple connections to MongoDB from one connect() call

问题描述

我正在 Node.js Express 应用程序中通过 Mongoose 与 MongoDB 建立单一连接:

I am making a single connection to MongoDB via Mongoose in Node.js Express app:

var express = require('express');
var mongoose = require('mongoose');
mongoose.connect('localhost', 'test');

然后我定义架构，然后是模型，最后是从数据库中提取所有用户的控制器:

I then define schema, followed by models, and lastly the controller that pulls all users from the database:

app.get('/users', function (req, res) {
  return User.find(function (err, users) {
    if (!err) {
      return res.send(users);
    }
  });
});

这些数据库连接在应用程序启动期间打开，并且在 node.js 应用程序期间保持打开状态.

These DB connections open during the application start and they stay open for the duration of the node.js application.

困扰我的是为什么我打开了 5 个连接?一旦我关闭 node.js 应用程序，所有 5 个连接都将关闭.

What bothers me is why do I have 5 connections open? As soon as I close the node.js app, all 5 connections are closed.

相关说明:对于 REST API 服务器，最好始终打开 MongoDB 连接.还是根据每个用户请求手动打开/关闭连接更好?

Related note: For a REST API server is it better to have MongoDB connection always open. Or is it better to manually open/close connections per each user request? d

推荐答案

那是因为 Mongoose 使用了 5 个连接池(默认情况下)，这些连接在整个应用程序中共享.为了获得最佳性能，最好让它们保持打开状态.

That's because Mongoose uses a pool of 5 connections (by default) that are shared throughout your application. For best performance, it's best to just leave them open.

您可以通过将选项参数更改为 mongoose.connect 来更改默认行为.例如:

You can alter the default behavior via the options parameter to mongoose.connect. For example:

mongoose.connect('localhost', 'test', { server: { poolSize: 3 }}); // Use 3 connections

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