MongoDB Refusing Connection using Java + Eclipse

Question

When I run the following simple code, I typically get a connection refused error... but 1 time out of 20 it will work randomly. Then continue working repeatedly for 2-3 minutes, then refuse connections again. I can't detect a pattern. I have looked at the other connection refused threads but they are using differing technologies that may or may not be complicating the situation (and unfortunately not every thread is even resolved).

I am completely new to Mongo and am following this guide: http://docs.mongodb.org/ecosystem/tutorial/getting-started-with-java-driver/ . My goal is to have a stable connection so I can experiment/learn the DB. Any help with this matter is greatly appreciated! Keep in mind I'm completely new to this technology and don't know my way around it yet.

I am using JDK 1.7.0_25 and Eclipse. I have added mongo-driver-2.11.3.jar to my project's build path already. The following is my simple code, directly from the example on the site I listed.

package database;

import java.util.Set;
import com.mongodb.MongoClient;
import com.mongodb.MongoException;
import com.mongodb.WriteConcern;
import com.mongodb.DB;
import com.mongodb.DBCollection;
import com.mongodb.BasicDBObject;
import com.mongodb.DBObject;
import com.mongodb.DBCursor;
import com.mongodb.ServerAddress;

public class MongoPortal {

    /*static final String domain = "localhost";  
    static final int port = 27107;
    static final String database = "test";*/

    public boolean insert(){

        try {
            MongoClient mongoClient = new MongoClient( "localhost" , 27107 );

            DB db = mongoClient.getDB("test");

            // Get and print all the collections
            Set<String> colls = db.getCollectionNames();
            for (String s : colls)
                System.out.println(s);

            mongoClient.close();
        }
        catch (Exception e){
            e.printStackTrace();
            return false;
        }

        return true;
    }
}

And the error I get:

Oct 13, 2013 9:12:50 AM com.mongodb.DBTCPConnector initDirectConnection
WARNING: Exception executing isMaster command on localhost/127.0.0.1:27107
java.net.ConnectException: Connection refused
    at java.net.PlainSocketImpl.socketConnect(Native Method)
    at java.net.AbstractPlainSocketImpl.doConnect(AbstractPlainSocketImpl.java:339)
    at java.net.AbstractPlainSocketImpl.connectToAddress(AbstractPlainSocketImpl.java:200)
    at java.net.AbstractPlainSocketImpl.connect(AbstractPlainSocketImpl.java:182)
    at java.net.SocksSocketImpl.connect(SocksSocketImpl.java:392)
    at java.net.Socket.connect(Socket.java:579)
    at com.mongodb.DBPort._open(DBPort.java:223)
    at com.mongodb.DBPort.go(DBPort.java:125)
    at com.mongodb.DBPort.go(DBPort.java:106)
    at com.mongodb.DBPort.findOne(DBPort.java:162)
    at com.mongodb.DBPort.runCommand(DBPort.java:170)
    at com.mongodb.DBTCPConnector.initDirectConnection(DBTCPConnector.java:547)
    at com.mongodb.DBTCPConnector.checkMaster(DBTCPConnector.java:526)
    at com.mongodb.DBTCPConnector.innerCall(DBTCPConnector.java:236)
    at com.mongodb.DBTCPConnector.call(DBTCPConnector.java:216)
    at com.mongodb.DBApiLayer$MyCollection.__find(DBApiLayer.java:288)
    at com.mongodb.DBApiLayer$MyCollection.__find(DBApiLayer.java:273)
    at com.mongodb.DB.getCollectionNames(DB.java:400)
    at database.MongoPortal.insert(MongoPortal.java:29)
    at driver.Driver.main(Driver.java:22)

Oct 13, 2013 9:12:50 AM com.mongodb.DBPortPool gotError
WARNING: emptying DBPortPool to localhost/127.0.0.1:27107 b/c of error
java.net.ConnectException: Connection refused
    at java.net.PlainSocketImpl.socketConnect(Native Method)
    at java.net.AbstractPlainSocketImpl.doConnect(AbstractPlainSocketImpl.java:339)
    at java.net.AbstractPlainSocketImpl.connectToAddress(AbstractPlainSocketImpl.java:200)
    at java.net.AbstractPlainSocketImpl.connect(AbstractPlainSocketImpl.java:182)
    at java.net.SocksSocketImpl.connect(SocksSocketImpl.java:392)
    at java.net.Socket.connect(Socket.java:579)
    at com.mongodb.DBPort._open(DBPort.java:223)
    at com.mongodb.DBPort.go(DBPort.java:125)
    at com.mongodb.DBPort.call(DBPort.java:92)
    at com.mongodb.DBTCPConnector.innerCall(DBTCPConnector.java:244)
    at com.mongodb.DBTCPConnector.call(DBTCPConnector.java:216)
    at com.mongodb.DBApiLayer$MyCollection.__find(DBApiLayer.java:288)
    at com.mongodb.DBApiLayer$MyCollection.__find(DBApiLayer.java:273)
    at com.mongodb.DB.getCollectionNames(DB.java:400)
    at database.MongoPortal.insert(MongoPortal.java:29)
    at driver.Driver.main(Driver.java:22)

com.mongodb.MongoException$Network: Read operation to server localhost/127.0.0.1:27107 failed on database test
    at com.mongodb.DBTCPConnector.innerCall(DBTCPConnector.java:253)
    at com.mongodb.DBTCPConnector.call(DBTCPConnector.java:216)
    at com.mongodb.DBApiLayer$MyCollection.__find(DBApiLayer.java:288)
    at com.mongodb.DBApiLayer$MyCollection.__find(DBApiLayer.java:273)
    at com.mongodb.DB.getCollectionNames(DB.java:400)
    at database.MongoPortal.insert(MongoPortal.java:29)
    at driver.Driver.main(Driver.java:22)
Caused by: java.net.ConnectException: Connection refused
    at java.net.PlainSocketImpl.socketConnect(Native Method)
    at java.net.AbstractPlainSocketImpl.doConnect(AbstractPlainSocketImpl.java:339)
    at java.net.AbstractPlainSocketImpl.connectToAddress(AbstractPlainSocketImpl.java:200)
    at java.net.AbstractPlainSocketImpl.connect(AbstractPlainSocketImpl.java:182)
    at java.net.SocksSocketImpl.connect(SocksSocketImpl.java:392)
    at java.net.Socket.connect(Socket.java:579)
    at com.mongodb.DBPort._open(DBPort.java:223)
    at com.mongodb.DBPort.go(DBPort.java:125)
    at com.mongodb.DBPort.call(DBPort.java:92)
    at com.mongodb.DBTCPConnector.innerCall(DBTCPConnector.java:244)
    ... 6 more

When I type mongo in bash, the display I get is:

@debian:~$ mongo
MongoDB shell version: 2.4.6
connecting to: test
> 

Answer 1

while you can connect with the mongo command it is definite that the mongodb server listen on the port 27017 (while without parameters it tries to connect there). That means in the java code you have to change this line:

MongoClient mongoClient = new MongoClient( "localhost" , 27107 );

To this line:

MongoClient mongoClient = new MongoClient( "localhost" , 27017 );

And i am not sure this behavior of the driver that give back connection refused if there is no server listening on a host:port config is something which is good. At least a bit misleading from my point of view.

Answer 2

Got the same error when mongodb was newly installed on our cluster. Code worked when i run the java program on the server mongodb was installed with localhost .

To run the code outside the cluster , got the connection refused error.

The issue was :

Port on which mongodb was installed was limited to localhost. We corrected and restarted the service and it worked perfect !!

Answer 3

I solved this error by giving a --dbpath to mongod and migrating my entire DB there.. Now everytime I start the server(mongod), I give --dbpath. Earlier I wasn't using a --dbpath..