如何使用mongoose或mongodb客户端关闭来自节点js的mongodb连接

there are approximately 21000 connections are there for mongodb which are stale connections.

i have tried "currentOp" command to list all the connections. i was unable to close from node js using mongoose.

const express = require('express');
var app = express();
const mongoose = require('mongoose'),
Admin = mongoose.mongo.Admin;
const port = 3002
mongoose.set('debug', true)
var db = mongoose.createConnection('mongodb://localhost:22222/myapp', { 
useNewUrlParser: true }, () => {
  console.log('Connection db established')
})
app.use((req, res, next) => {
    console.log(req.url + ' ' + new Date());
    next();
});
const Cat = mongoose.model('cats', { name: String });

db.on('open', function (err, data) {


    new Admin(db.db).command({ currentOp: 1, '$all': true }, (err, r) => {
        var connections = []
        console.log(err)
        console.log(r.inprog.length)
        r.inprog.forEach((conn) => {
            if (conn.client) {
                console.log(conn.client)
                connections.push({ thread: conn.threadId, connection: conn.connectionId, op: conn.opid })
            }
        })
        console.log(connections)
    })
});

app.listen(port, () => {
    console.log('Server started')
})

i have used "killOp" to kill connection but didn't work. and there is no "opid" for stale connections to kill or to identify

Your mongoose connection can be closed with

mongoose.connection.close()

Make sure to put in the correct callback however, so that your database gets saved before the connection closes.

You can read more in the docs found here.