for (int i = 0; i < 10000; i++) {
            final int counter = i;
            CompletableFuture.supplyAsync(() -> {

                System.out.println("Looking up " + counter + " on thread " + Thread.currentThread().getName());
                return null;
            });
}

Looking up 0 on thread Thread-2
Looking up 1 on thread Thread-3
Looking up 2 on thread Thread-4
...
Looking up 10000 on thread Thread-10002