Basic producer-consumer loop BlockingCollection

var collection = new BlockingCollection<int>(5);
var random = new Random();

var producerTask = Task.Run(() => {
    for(int item=1; item<=10; item++) 
    {
        collection.Add(item);
        Console.WriteLine("Produced: " + item);
        Thread.Sleep(random.Next(10,1000));
    }
    collection.CompleteAdding();
    Console.WriteLine("Producer completed!");
});

It is worth noting that if you do not call collection.CompleteAdding();, you are able to keep adding to the collection even if your consumer task is running. Just call collection.CompleteAdding(); when you are sure there are no more additions. This functionality can be used to make a Multiple Producer to a Single Consumer pattern where you have multiple sources feeding items into the BlockingCollection and a single consumer pulling items out and doing something with them. If your BlockingCollection is empty before you call complete adding, the Enumerable from collection.GetConsumingEnumerable() will block until a new item is added to the collection or BlockingCollection.CompleteAdding(); is called and the queue is empty.

var consumerTask = Task.Run(() => {
    foreach(var item in collection.GetConsumingEnumerable())
    {
        Console.WriteLine("Consumed: " + item);
        Thread.Sleep(random.Next(10,1000));
    }
    Console.WriteLine("Consumer completed!");
});
  
Task.WaitAll(producerTask, consumerTask);
       
Console.WriteLine("Everything completed!");