Testing Conflation of data in Dequeue

I have a Data structure implemented which involves LinkedBlockingDequeue which I need to test. Suppose I have 10 data to be inserted from one end and also from other end I retrieve values. Now these two threads run simultaneously. Now while inserting data it is possible that a for a particu开发者_开发知识库lar "key" a second update comes on that key, so if the value corresponding to that data has not been retrieved, what the user should get on retrieval is the new data.

I need to test that this operation is actually operating. Can anybody tell me how to do that?