Node.js Mongoose在第二次请求时打开2个到DB的连接

我正在编写一个小节点，通过Mongoose进行简单的查询来监视MongoDB。如果有东西被退回，服务将被视为可用。这是我的剧本

var res;
var logPrefix = '[MongoDB]';
var counter = 0;

var mongoose = require('mongoose');
// Simple schema and model for getting a companyprofiles document
var companyProfile = new mongoose.Schema({
    _id: String
});
companyProfile.virtual('Id').get(function () {return this._id});

function closeConnection() {
    console.log('8');
    mongoose.connection.close(function () {
        console.log('9');
        console.log('%s Closed connection%d', logPrefix, counter);
    });
}

function connectAndCheckHealth() {
    console.log('2');
    mongoose.connect('mongodb://localhost:27017/testdb');

    console.log('3');
    mongoose.connection.on('error', function(err) {
        console.log('%s Error connecting to DB:\n%s %s', logPrefix, logPrefix, err);
        res.send(503, 'ERR');
    });

    mongoose.connection.on('open', function() {
        mongoose.connection.db.serverConfig.options.auto_reconnect = false;
    });

    console.log('4');
    mongoose.connection.on('connected', checkHealth);

    console.log('5');
    mongoose.connection.on('close', function() {
        console.log('%s Connection to MongoDB closed %d', logPrefix, counter);
    });
}

function checkHealth() {
    console.log('6');
    cpModel = mongoose.model('companyProfile', companyProfile, 'companyprofiles');
    cpModel.findById('spin', handleModelResponse);
}

function handleModelResponse(error, doc) {
    console.log('7');
    closeConnection();
    console.log('10');
    if (error !== null) {
        console.log('11');
        console.log('%s Error handling response from model:\n%s %s', logPrefix, logPrefix, error);
        res.send(503, 'ERR');
    } else {
        console.log('12');
        if (doc.Id.match(/company1/)) {
            console.log('13');
            console.log('%s App status is ok', logPrefix);
            res.send(200, 'OK');
        } else {
            console.log('14');
            console.log('%s Couldn\'t find the spin company profile. Found %s', logPrefix, doc.Id);
            res.send(503, 'ERR');
        }
    }
}

module.exports = {
    health: function(response) {
        counter++;
        var date = new Date();
        console.log('%s Retrieving health from MongoDB at %s', logPrefix, date);
        res = response;
        console.log(mongoose.connection);
        console.log('1');
        connectAndCheckHealth();
        console.log('15');
    }
}

如您所见，我在脚本中添加了带有数字的console.log行，以尝试计算控制流。以下是输出：

1
2
3
4
5
15
6
6
6
7
8
[MongoDB] Connection to MongoDB closed 3
[MongoDB] Connection to MongoDB closed 3
[MongoDB] Connection to MongoDB closed 3
9
[MongoDB] Closed connection3
10
12
13
[MongoDB] App status is ok
7
8
9
[MongoDB] Closed connection3
10
12
13
[MongoDB] App status is ok

/home/GTP/healthcheck/node_modules/mongoose/lib/utils.js:413
        throw err;
              ^
Error: Can't set headers after they are sent.

请注意，连接后，6在回调中出现三次。我不知道我们为什么要打开多个连接。我已关闭自动连接，并在每次请求后关闭连接

---

任何帮助都将不胜感激。

Mongoose默认打开5个连接池；如果您只需要一个连接，您可以将连接呼叫更改为：

mongoose.connect('mongodb://localhost:27017/testdb', { server: { poolSize: 1 }});

---

Mongoose默认打开5个连接池；如果您只需要一个连接，您可以将连接呼叫更改为：

mongoose.connect('mongodb://localhost:27017/testdb', { server: { poolSize: 1 }});

---

db.once“open”对我有用

---

在测试我的页面时，我注意到双重和快速表单提交会触发关于已发送的标题的错误。这就停止了。

db.“打开”一词对我有用

---

在测试我的页面时，我注意到双重和快速表单提交会触发关于已发送的标题的错误。这就停止了。

我刚试过这个。它并没有阻止原帖子中描述的相同场景。@brimble2010怪异。尝试对“已连接”事件使用once而不是on:mongoose.connection.一旦“已连接”，请检查健康状况；你的回答和评论为我解决了这个问题。谢谢我刚试过这个。它并没有阻止原帖子中描述的相同场景。@brimble2010怪异。尝试对“已连接”事件使用once而不是on:mongoose.connection.一旦“已连接”，请检查健康状况；你的回答和评论为我解决了这个问题。谢谢