Question

我偶然发现了一个关于mongoose连接mongodb的奇怪问题，它产生了如下细节错误

    e:\Mentor_Resources\node\node_twitter_bootstrap>node app
Express server listening on port 3000
Trace: error occure when start to connect dbError: connection closed
    at e:\Mentor_Resources\node\node_twitter_bootstrap\server\module\word.js:14:
17
    at Connection.open (e:\Mentor_Resources\node\node_twitter_bootstrap\node_mod
ules\mongoose\lib\connection.js:201:5)
    at Db.open (e:\Mentor_Resources\node\node_twitter_bootstrap\node_modules\mon
goose\node_modules\mongodb\lib\mongodb\db.js:247:16)
    at Server.connect.connectionPool.on.server._serverState (e:\Mentor_Resources
\node\node_twitter_bootstrap\node_modules\mongoose\node_modules\mongodb\lib\mong
odb\connection\server.js:413:7)
    at EventEmitter.emit (events.js:115:20)
    at connection.on.connectionStatus (e:\Mentor_Resources\node\node_twitter_boo
tstrap\node_modules\mongoose\node_modules\mongodb\lib\mongodb\connection\connect
ion_pool.js:108:15)
    at EventEmitter.emit (events.js:91:17)
    at Socket.closeHandler (e:\Mentor_Resources\node\node_twitter_bootstrap\node
_modules\mongoose\node_modules\mongodb\lib\mongodb\connection\connection.js:401:
12)
    at Socket.EventEmitter.emit (events.js:88:17)
    at Socket._destroy.destroyed (net.js:364:10)

mongoose的代码片段是：

var mongoose = require('mongoose');

mongoose.connect("mongodb://localhost/word-sentence",function(err) {
    if(err)
        console.trace('error occure when start to connect db' + err);
});

我确定mongodb是开放的，我重启mongodb几次，但错误仍然存在，所以我重新启动我的Windows XP，再试一次问题消失，一切正常，所以我想知道为什么？

Answer 1

当较长时间运行的应用程序中的池连接返回connection closed时，这是一个常见问题。

mongoose documentation建议将keepAlive添加到您传递到connect函数的选项对象中。

以下是一个示例（如果您不使用此内容，则可以删除replset），

// include keep alive for closing connections,
// http://tldp.org/HOWTO/TCP-Keepalive-HOWTO/overview.html
var mongoOptions =
{
    db: {safe: true},
    server: {
        socketOptions: {
            keepAlive: 1
        }
    },
    replset: {
        rs_name: 'myReplSet',
        socketOptions: {
            keepAlive: 1
        }
    }
};

mongoose.connect( YOUR_URI, mongoOptions );

mongoose.connection.on('error', function(err) {
    console.log('Mongo Error:\n');
    console.log(err);
}).on('open', function() {
    console.log('Connection opened');
});

Answer 2

mongoose.connect()不接受您在代码中使用的任何回调函数，即您的mongoose代码段：

var mongoose = require('mongoose');

mongoose.connect("mongodb://localhost/word-sentence",function(err) {
    if(err)
        console.trace('error occurred, when attempted to connect db. Error: ' + err);
});

所以，我建议你从这开始：

var mongoose = require('mongoose');
mongoose.connect('mongodb://localhost/word-sentence');
var db = mongoose.connection;
db.on('error', console.error.bind(console, 'connection error:'));
db.once('open', function callback () {
  // yay connected!
});

同样，你不能指望来自db.open('open', function cb(){})

的回调中的任何参数

我建议您仔细阅读这些quick start，mongoose docs - 如果在文档和文档中发现某些冲突，您可以了解如何跳转到源代码中。 mongodb/mongoose close connection

mongoose输出错误“错误：连接关闭”

2 个答案: