Mongo connection leak with morphia

java, mongodb, morphia

Solution

You can create a `singleton` `Datastore` object

public enum MongoDBHelper { // the best way to implement singletons, due to the author of Effective Java  
INSTANCE;

private DB db;
private Datastore datastore;

private final String SERVER_URL = "...";
private final int SERVER_PORT = ...;
private final String USERNAME= "...";
private final String PASSWORD = "...";
private final String DATABASE_NAME = "...";

private MongoDBHelper() {

    try {

        MongoClient mongoClient = new MongoClient(SERVER_URL, SERVER_PORT);

        this.db = mongoClient.getDB(DATABASE_NAME);
        this.db.authenticate(USERNAME,PASSWORD.toCharArray());

        Morphia morphia = new Morphia();

        this.datastore = morphia.createDatastore(mongoClient, DATABASE_NAME);

        morphia.mapPackage("package");
    } catch (UnknownHostException e) {
        e.printStackTrace();
    }

}

public DB getDB() {
    return this.db;
}

public Datastore getDatastore() {
    return this.datastore;
}
}

and now you can reuse the same `Datastore` object in your application

 Datastore datastore = MongoDBHelper.INSTANCE.getDatastore()

Problem

I have a `Servlet` with `static Mongo = new Mongo()` and `Morphia morphia = new Morphia()` objects. Each time `GET` is invoked, I do the following: ``` doGet(...){ ... datastore = morphia.createDatastore(mongo, dbName); ... } ``` I don't close `datastore`, because there is no close method. Each time i invoke the servlet, number of used connections in mongo grow: ``` { "current" : 113, "available" : 706, "totalCreated" : NumberLong(122) } > db.serverStatus().connections { "current" : 115, "available" : 704, "totalCreated" : NumberLong(124) } > db.serverStatus().connections { "current" : 116, "available" : 703, "totalCreated" : NumberLong(125) } > db.serverStatus().connections { "current" : 121, "available" : 698, "totalCreated" : NumberLong(130) } > db.serverStatus().connections { "current" : 122, "available" : 697, "totalCreated" : NumberLong(131) } > db.serverStatus().connections { "current" : 128, "available" : 691, "totalCreated" : NumberLong(137) } ``` what is the right way to close connections with mongo and morphia and where the connection is really leaking? Thanks.

Original source