Question

I am circling through LinkedBlockingQueue millions of Strings.
The reading thread should end its execution when there are no more items in source.

I thought about putting a dummy value like "SHUTDOWN" in LinkedBlockingQueue.

The reader does this:

while ((data = (String)MyLinkedBlockingQueue.take()).equals("SHUTDOWN") == false) {
    //read and live 
}

Is it efficient to execute equals on every string? If not what can I use instead?

Answer 1

You are on the right track. This is the standard idiom for finishing processing of a BlockingQueue, it’s called the “poison pill”. i usually implement it using a special private static final instance so you can do object equality and don’t risk overlapping with a real value. e.g.:

private static final String SHUTDOWN = new String("SHUTDOWN"); // use new String() so you don't get an interned value

public void readQueue() {
  while ((data = (String)MyLinkedBlockingQueue.take()) != SHUTDOWN) {
      //read and live 
  }
}

public void shutdownQueue() {
  MyLinkedBlockingQueue.put(SHUTDOWN);
}