Question

我是nodejs和mongdb的新手，我将在我的一个项目中使用它，一旦我的数据库连接正常工作，我很震惊地看到我的代码确实有多少数据库连接。所以，给出这个简单的代码片段：

var express = require('express');
var mongo = require('mongodb');  
var app = express();

// Further details:
// nodejs: v0.8.18
// mongod: v2.2.2
// node's mongodb driver: v1.2.10

app.get('/', function(req, res){
    res.send('<h1>Ok</h1>');
});

var setUp = function() {   
    // get a handler to the testDB Database
    mongo.Db.connect('mongodb://localhost:27017/testDB', function(err, db) {
        if (err)
            throw err;
        // create a test collection in the database
        db.createCollection('test', function(err, test) {
            if (err)
                throw err;
            // insert a dummy document into the test collection          
            test.insert({'name':'admin', 'pass':'admin'});

            app.listen(3000); 
            console.log('App listening on port 3000');
        });
    });
}

setUp();

当nodejs进程启动时，mongo守护程序输出这一部分日志：

... connection accepted from 127.0.0.1:40963 #34 (1 connection now open)
... connection accepted from 127.0.0.1:40964 #35 (2 connections now open)
... connection accepted from 127.0.0.1:40965 #36 (3 connections now open)
... connection accepted from 127.0.0.1:40966 #37 (4 connections now open)
... connection accepted from 127.0.0.1:40967 #38 (5 connections now open)
... connection accepted from 127.0.0.1:40968 #39 (6 connections now open)
... end connection 127.0.0.1:40963 (5 connections now open)
... allocating new datafile /var/data/testDB.ns, filling with zeroes...
...

这个过程终止时的那个：

... connection 127.0.0.1:40964 (4 connections now open)
... connection 127.0.0.1:40965 (3 connections now open)
... connection 127.0.0.1:40966 (2 connections now open)
... connection 127.0.0.1:40967 (1 connection now open)
... connection 127.0.0.1:40968 (0 connections now open)

mongo驱动程序是否真的需要与mongod建立多个连接才能获得单个数据库处理程序，或者我实现此方法有什么问题？我真的希望在那里看到一个开放的连接...

Answer 1

默认情况下，

Db.connect会打开一个包含5个连接的池。如果您想将其限制为单个连接，可以通过server选项将其限制为：

mongo.Db.connect(
    'mongodb://localhost:27017/testDB', 
    {server: {poolSize: 1}}, 
    function(err, db) { ...

Answer 2

您也可以像那样传递

var mongoclient = new mongodb.MongoClient(new mongodb.Server(
    'localhost', 27017, {'native_parser': true, 'poolSize': 1} 
));

MongoDB：＆gt;单个数据库处理程序的5个打开连接

2 个答案: