FULL PRODUCT VERSION :
java version "1.5.0_06"
Java(TM) 2 Runtime Environment, Standard Edition (build 1.5.0_06-b05)
Java HotSpot(TM) Client VM (build 1.5.0_06-b05, mixed mode, sharing)

ADDITIONAL OS VERSION INFORMATION :
Windows XP Pro sp2

EXTRA RELEVANT SYSTEM CONFIGURATION :
multiple threads

A DESCRIPTION OF THE PROBLEM :
Caused by: java.lang.NullPointerException
            at java.util.concurrent.LinkedBlockingQueue.peek(LinkedBlockingQueue.java:440)

this function is

    public E peek() {
        if (count.get() == 0)
            return null;
        final ReentrantLock takeLock = this.takeLock;
        takeLock.lock();
        try {
            Node<E> first = head.next;
            if (first == null)
                return null;
            else
                return first.item;
        } finally {
            takeLock.unlock();
        }
    }

line 440 is Node<E> first = head.next;

i think that you need to add in line 440

        if (count.get() == 0)
            return null;

a second time. the difference this time is that you are in a protected section enforced by takeLock.lock();

thanks.
 


REPRODUCIBILITY :
This bug can be reproduced occasionally.