Producer/Consumer - Calculate average time

Question

I have 4 class - Producer, Consumer, Shop, Main.

Trying to calculate average waiting time which customers are in the queue for waiting to enter the store.

My run method in Producer -

public void run() {
  for (int i = 1; i < size; i++) {

     shop.put(i);
     System.out.println("Customer number "  + i + " has entered the store\n");
     enterStore = System.currentTimeMillis();
     try {
        Thread.sleep((int) (Math.random() * 1000));

     } catch (InterruptedException e) { }
  }
}

Part of my put method in Shop -

System.out.println("The store is full! Customer " + value + " is waiting in the queue.....\n");
        queueStart = System.currentTimeMillis();
        System.out.println("Customer joined queue at time : " + queueStart);

        wait();

And part of my Main -

double averageTime = (Shop.queueStart - Producer.enterStore)/20;
  System.out.println("Average time customer queued outside store = " + averageTime);

Everything else in my code is working fine - but the average prints a minus number so I've obviously gone wrong somewhere. I'm really new to java and just looking for some help!

Thanks!

Well, since you enter the store after joining the queue, you should probably reverse the order - `double averageTime = ( Producer.enterStore - Shop.queueStart)/20;` — Eran, Apr 01 '14 at 19:43
This isn't related to your question, but using a Thread.sleep(int) is not the best way to solve the producer-consumer problem. Consider working with wait() and notify(), or, better, semaphores http://en.wikipedia.org/wiki/Semaphore_(programming) — Dylan Meeus, Apr 01 '14 at 19:48

score 0 · Accepted Answer · answered Apr 01 '14 at 19:43

0

The later the time, the higher the double value, therefore you need to switch the subtraction operands, so that you get

Producer.enterStore - Shop.queueStart

answered Apr 01 '14 at 19:43

Warlord

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Producer/Consumer - Calculate average time

1 Answers1