BAEL-614 introduced poison pill message to stop our producers form run indefinitely

core-java/src/main/java/com/baeldung/concurrent/blockingqueue/BlockingQueueUsage.java

@@ -9,16 +9,18 @@ public class BlockingQueueUsage {
         int BOUND = 10;
         int N_PRODUCERS = 4;
         int N_CONSUMERS = Runtime.getRuntime().availableProcessors();
+        int poisonPill = Integer.MAX_VALUE;
+        int poisonPillPerProducer = N_CONSUMERS / N_PRODUCERS;
 
 
         BlockingQueue<Integer> queue = new LinkedBlockingQueue<>(BOUND);
 
         for (int i = 0; i < N_PRODUCERS; i++) {
-            new Thread(new NumbersProducer(queue)).start();
+            new Thread(new NumbersProducer(queue, poisonPill, poisonPillPerProducer)).start();
         }
 
         for (int j = 0; j < N_CONSUMERS; j++) {
-            new Thread(new NumbersConsumer(queue)).start();
+            new Thread(new NumbersConsumer(queue, poisonPill)).start();
         }
     }
 }

core-java/src/main/java/com/baeldung/concurrent/blockingqueue/NumbersConsumer.java

@@ -5,15 +5,20 @@ import java.util.concurrent.BlockingQueue;
 
 class NumbersConsumer implements Runnable {
     private final BlockingQueue<Integer> queue;
+    private final int poisonPill;
 
-    public NumbersConsumer(BlockingQueue<Integer> queue) {
+    public NumbersConsumer(BlockingQueue<Integer> queue, int poisonPill) {
         this.queue = queue;
+        this.poisonPill = poisonPill;
     }
 
     public void run() {
         try {
             while (true) {
                 Integer number = queue.take();
+                if (number.equals(poisonPill)) {
+                    return;
+                }
                 String result = number.toString();
                 System.out.println(Thread.currentThread().getName() + " result: " + result);
 

core-java/src/main/java/com/baeldung/concurrent/blockingqueue/NumbersProducer.java

@@ -8,10 +8,14 @@ import java.util.concurrent.BlockingQueue;
 class NumbersProducer implements Runnable {
     private final Random random = new Random();
     private final BlockingQueue<Integer> numbersQueue;
+    private final int poisonPill;
+    private final int poisonPillPerProducer;
 
 
-    public NumbersProducer(BlockingQueue<Integer> numbersQueue) {
+    public NumbersProducer(BlockingQueue<Integer> numbersQueue, int poisonPill, int poisonPillPerProducer) {
         this.numbersQueue = numbersQueue;
+        this.poisonPill = poisonPill;
+        this.poisonPillPerProducer = poisonPillPerProducer;
     }
 
 
@@ -27,5 +31,8 @@ class NumbersProducer implements Runnable {
         for (int i = 0; i < 100; i++) {
             numbersQueue.put(random.nextInt(100));
         }
+        for (int j = 0; j < poisonPillPerProducer; j++) {
+            numbersQueue.put(poisonPill);
+        }
     }
 }