collection.find(<query>).first() not returning NULL, if the item is not present

[Himani Garg]

I am writing a Java application, which makes connection to Mongo DB, creates the database and collection (if it doesn't exist), and then searches for a value in the collection. If it returns NULL, then a new value is added in collection, else the same value is returned.

I tried "collection.find().first()". This should return null, in case the item doesn't exist. But in my case, it is throwing an exception (not sure though) which is- "Attempted to decrement the reference count below 0". The find() method is running as usual, this exception is thrown in first() method (during binding.release() during execute in Mongo.java).

Code:

MongoDatabase database = mongoClient.getDatabase(this.databaseName);
MongoCollection<Document> collection = database.getCollection(this.collectionName);
FindIterable<Document> documents = collection.find(spec);
Document firstDocument = (Document)documents.first();

Expected: null, Actual Result: Exception

Is there any possible reason for it?

I also tried the iterator method, but same thing is happening. During find it is working perfectly, but it is throwing an exception during .iterator().

[Jeff Yemin]

This seems like a bug, but to diagnose further please provide the full stack trace of the exception.

Regards,

Jeff