Question

I have a multi threaded application which has one producer thread and several consumer threads.
The data is stored in a shared thread safe collection and flushed to a database when there is sufficient data in the buffer.

From the javadocs –

BlockingQueue<E>

A Queue that additionally supports operations that wait for the queue to become non-empty when retrieving an element, and wait for space to become available in the queue when storing an element.

take()

Retrieves and removes the head of this queue, waiting if necessary until an element becomes available.

My questions –

1. Is there another collection that has a E[] take(int n) method? i.e. Blocking queue waits until an element is available. What I want is
   that it should wait until 100 or 200 elements are available.
2. Alternatively, is there another method I could use to address the problem without polling?

Answer 1

I think the only way is to either extend some implementation of BlockingQueue or create some kind of utility method using take:

public <E> void take(BlockingQueue<E> queue, List<E> to, int max) 
        throws InterruptedException {

    for (int i = 0; i < max; i++)
        to.add(queue.take());
}