Mongo failed to connect to server on first connect

问题

I know that's a way discussed issue, and have gone through almost every topic I found on SO and google in general about it, but still no resolution!

The problem

At random points in time, the following error occurs

MongoError: failed to connect to server [127.0.0.1:20000] on first connect
    at Pool.<anonymous> (/home/user/node_modules/mongodb-core/lib/topologies/server.js:326:35)
    at emitOne (events.js:96:13)
    at Pool.emit (events.js:189:7)
    at Connection.<anonymous> (/home/user/node_modules/mongodb-core/lib/connection/pool.js:270:12)
    at Object.onceWrapper (events.js:291:19)
    at emitTwo (events.js:106:13)
    at Connection.emit (events.js:192:7)
    at Socket.<anonymous> (/home/user/node_modules/mongodb-core/lib/connection/connection.js:185:10)
    at Object.onceWrapper (events.js:291:19)
    at emitNone (events.js:86:13)

The solution

Kill the application, restart the mongod service (so the .lock file is deleted) and restart the application. Now everything runs smoothly. Obviously that's not a accepted solution!

The environment and the facts

The application is written using:

ExpressJS framework (version 4.15.2)
MongoJS driver (version 2.4.0)
NodeJS (version 7.7.3)
MongoDB (version 3.4.2)

Server is a VPS (OpenVZ) running Centos 7.

MongoDB was installed using the recommended .rpm method exactly as described in the docs.

Even when the application crashes with the aforementioned error, I'm able to connect and issue queries via shell.

There is nothing in the logs about that error or something that may cause it. The only startup warnings are about using xfs instead of ext4 and about using MongoDB with OpenVZ.

The only configuration change made to mongod.conf was the listening port and enabling authorization.

The connection string used with mongojs is the following

var mongojs = require('mongojs');
var db = mongojs('mongodb://username:password@127.0.0.1:20000/database')

The cry for help moment

Please guys! Help me out... It's really annoying and can't find out if it's me, the driver or settings that mess this up!

Thanks in advance

UPDATE

Removed the packaged version of the database and performed a manual installation, but still no results! The error persists...

回答1:

Here's what solved our problem.

Changed server and moved out of OpenVZ to a KVM "based" VPS. Every application element remained the same (app code/node/npm/mongo/drivers etc), and same OS (still Centos 7).

Not a single clue why, but the app is running perfectly on the new server for about a week instead of crashing every few minutes or hours...

Hope this helps someone!

来源：https://stackoverflow.com/questions/42946340/mongo-failed-to-connect-to-server-on-first-connect

标签

mongodb

mongojs