Is it possible to read stale value of non-volatile variable during read from another thread?

I have a main thread which constructs an object with a non-volatile variable and then in this thread I change the value of the variable and put the object to BlockingQueue.
In second thread I wait until the object be available and read the object and its variable.

Example code:

public class ReadCheck {
    static BlockingQueue<A> queue = new LinkedBlockingQueue<>();
    public static class A {
        public int a;
        public A(int a) {
            this.a = a;
        }
    }
    public static void main(String[] args) throws InterruptedException {
        new Thread(new Runnable() {
            @Override
            public void run() {
                while (true) {
                    try {
                        A a = queue.take();
                        if (a.a != 20) {
                            System.out.println(a.a);
                        }
                    } catch (InterruptedException e) {
                    }
                }
            }
        }).start();
        while (true) {
            A a = new A(10);
            a.a = 20;
            queue.offer(a);
        }
    }
}

During run of example I've never seen that variable is 10 (it's always 20).
Is it possible that I read stale value (10) of variable in second thread in such case?
Is this code example thread safe?

No, you can't read a stale value; yes, it will be thread safe.

The blocking queue guarantees that offer happens before take, so the write to the value in A.a will happen before you read it.

> As with other concurrent collections, actions in a thread prior to placing an object into a BlockingQueue happen-before actions subsequent to the access or removal of that element from the BlockingQueue in another thread.