Unterschiede

Hier werden die Unterschiede zwischen zwei Versionen angezeigt.

--- api:documentation:threads:start [2024/12/02 19:57] – [Monitorkonzept mit der Klasse Semaphore] martin
+++ api:documentation:threads:start [2025/03/05 10:26] (aktuell) – [synchronized-Block] martin
@@ Zeile 186: / Zeile 186: @@
-===== Monitorkonzept mit der Klasse Semaphore =====
+===== Die Klasse Semaphore =====
 <WRAP center round info 80%>
 Ein **Semaphor** ist ein Objekt, das einen Zähler enthält, dessen Wert angibt, von wie vielen Prozessen ein kritischer Abschnitt im Augenblick gerade noch betreten werden darf. \\  (**Bem.:** Eine andere Interpretation besteht darin, dass es  $n$  gleichartig Ressourcen gibt. Der Wert des Zählers gibt an, wie viele im Augenblick gerade zur Verfügung stehen.) \\ \\ Der Semaphor besitzt zwei Methoden:
@@ Zeile 253: / Zeile 253: @@
 </HTML>
+===== Monitorkonzept =====
+<HTML>
+<div class="java-online" style="height: 60vh; width: 90%" data-java-online="{'withBottomPanel': true, 'id': 'ConsumerProducer134'}">
+<script type="text/plain" title="Main.java">
+BlockingQueue<String> queue = new BlockingQueue<>(5);
+for (int i = 0; i < 3; i++) {
+   new Producer(queue, 100, i);
+   new MyConsumer(queue, 100, i);
+}
+while (true);
+class Producer implements Runnable {
+   BlockingQueue<String> queue;
+   int count;
+   int producerIndex;
+   Producer(BlockingQueue<String> queue, int count, int producerIndex) {
+      this.queue = queue;
+      this.count = count;
+      this.producerIndex = producerIndex;
+      Thread t = new Thread(this);
+      t.setName("Producer " + producerIndex);
+      t.start();
+   }
+   public void run() {
+      while (count > 0) {
+         queue.put(this.producerIndex + "/" + this.count);
+         println("P " + this.producerIndex + " added " + count, Color.lightblue);
+         count--;
+      }
+   }
+}
+class MyConsumer implements Runnable {
+   BlockingQueue<String> queue;
+   int count;
+   int consumerIndex;
+   MyConsumer(BlockingQueue<String> queue, int count, int consumerIndex) {
+      this.queue = queue;
+      this.count = count;
+      this.consumerIndex = consumerIndex;
+      Thread t = new Thread(this);
+      t.setName("Consumer " + consumerIndex);
+      t.start();
+   }
+   public void run() {
+      while (count > 0) {
+         String s = queue.take();
+         println("C " + this.consumerIndex + " removed " + s, Color.lightgreen);
+         count--;
+      }
+   }
+}
+</script>
+<script type="text/plain" title="BlockingQueue.java">
+public class BlockingQueue < T extends Object > {
+   private Queue<T> queue = new LinkedList<T>();
+   private int capacity;
+   public BlockingQueue(int capacity) {
+      this.capacity = capacity;
+   }
+   public synchronized void put(T element) {
+      while (queue.size() == capacity) {
+         wait();
+      }
+      queue.add(element);
+      notify(); // notifyAll() for multiple producer/consumer threads
+   }
+   public synchronized T take() {
+      while (queue.isEmpty()) {
+         wait();
+      }
+      T item = queue.remove();
+      notify(); // notifyAll() for multiple producer/consumer threads
+      return item;
+   }
+   public int size() {
+      return queue.size();
+   }
+}
+</script>
+</div>
+</HTML>
+===== synchronized-Block =====
+<HTML>
+<div class="java-online" style="height: 60vh; width: 90%" data-java-online="{'withBottomPanel': false, 'id': 'ThreadTest2'}">
+<script type="text/plain" title="ThreadTest1.java">
+Counter counter = new Counter();
+for (int i = 0; i < 3; i++) {
+   Incrementer inc = new Incrementer(counter, 1e6, i);
+   Thread t = new Thread(inc);
+   t.setName("Thread " + i);
+   t.start();
+}
+class Counter {
+   long counter = 0;
+}
+class Incrementer implements Runnable {
+   Counter counter;
+   long increment = 0;
+   int index;
+   Incrementer(Counter counter, long increment, int index) {
+      this.increment = increment;
+      this.counter = counter;
+      this.index = index;
+   }
+   public void run() {
+      for (long i = 0; i < increment; i++) {
+         if(i % (increment/10) == 0) println("Thread " + index + ": " + i);
+         synchronized (counter) {
+            long i = counter.counter;
+            i++;
+            counter.counter = i;
+         }
+      }
+      println("Thread " + index + " done. Counter: " + counter.counter);
+   }
+}
+</script>
+</div>
+</HTML>