How to keep the connection pool from closing with a java driver on a mongodb?

Question

I'm in the middle of upgrading from java driver 2.12.3 to 3.3.0. Curiously it seems that the collection pool is suddenly "acting up".

My set up is as follows:

The Connection is established in the main thread:

mongoClient = new MongoClient(new MongoClientURI("mongodb://localhost:27017"));
mongoClient.setWriteConcern(new WriteConcern(0, 10)); // deprecated, replace soon
database = mongoClient.getDatabase("Example");
// java.util.logging.Logger.getLogger("org.mongodb.driver").setLevel(Level.SEVERE);

It's used in hundreds of threads:

org.bson.Document oldDoc = DBInteractions.readOneFromDb("articles");

using functions like this:

static synchronized Document readOneFromDb(String col) {
    return database.getCollection(col).find().limit(1).sort(new Document().append("count", 1)).first();
}

And for every DB interaction I get such a warning:

Sep 26, 2016 2:33:19 PM com.mongodb.diagnostics.logging.JULLogger log
INFORMATION: Closed connection [connectionId{localValue:42, serverValue:248}] to localhost:27017 because the pool has been closed.

It looks as if the connection pool is closed after just one interaction. But why? very puzzled Anyone an idea?

Drawknife

No real answer, but a hint: you should have the MongoClient as the shared object which you only open up once and keep through lifetime. The MongoDatabase object is not thread-safe and should not be shared. – Myca

Answer 1

https://api.mongodb.com/java/3.1/com/mongodb/MongoClientOptions.html

Look at the link. There are several method that can probably help you. Look into the timeout related methods for connection and connection pool.

---

EDIT: added the correct answer (it was in the comments below)

MongoClientOptions options = new MongoClientOptions.Builder().socketKeepAlive(true).build(); 
MongoClient client = new MongoClient("host", options);

Butterfield

That 's what I did all afternoon, and the reason why I ask here. ;) Drawing a blank on more ideas. – Drawknife

see if this helps ' MongoClientOptions options = new MongoClientOptions.Builder().socketKeepAlive(true).build(); } and pass this options to MongoClient client = new MongoClient("host", options);' – Butterfield

great :) happy to help. – Butterfield

where do you add this? – Ruination

Answer 2

MongoClientOptions options = new MongoClientOptions.Builder().socketKeepAlive(true).build();

socketKeepAlive is now Deprecated.
It now defaults to true and disabling it is not recommended.

Kalamazoo