diff --git a/double-checked-locking/src/main/java/com/iluwatar/doublechecked/locking/App.java b/double-checked-locking/src/main/java/com/iluwatar/doublechecked/locking/App.java
index 80806e9eb..b8d6a41a0 100644
--- a/double-checked-locking/src/main/java/com/iluwatar/doublechecked/locking/App.java
+++ b/double-checked-locking/src/main/java/com/iluwatar/doublechecked/locking/App.java
@@ -2,6 +2,7 @@ package com.iluwatar.doublechecked.locking;
 
 import java.util.concurrent.ExecutorService;
 import java.util.concurrent.Executors;
+import java.util.concurrent.TimeUnit;
 
 /**
  * 
@@ -26,13 +27,17 @@ public class App {
 		final Inventory inventory = new Inventory(1000);
 		ExecutorService executorService = Executors.newFixedThreadPool(3);
 		for (int i = 0; i < 3; i++) {
-			executorService.execute(new Runnable() {
-				@Override
-				public void run() {
-					while (inventory.addItem(new Item()))
-						;
-				}
-			});
+			executorService.execute(() -> {
+                while (inventory.addItem(new Item()))
+                    ;
+            });
+		}
+
+		executorService.shutdown();
+		try {
+			executorService.awaitTermination(5, TimeUnit.SECONDS);
+		} catch (InterruptedException e) {
+			System.out.println("Error waiting for ExecutorService shutdown");
 		}
 	}
 }
diff --git a/double-checked-locking/src/main/java/com/iluwatar/doublechecked/locking/Inventory.java b/double-checked-locking/src/main/java/com/iluwatar/doublechecked/locking/Inventory.java
index 9f663f272..a58926d9d 100644
--- a/double-checked-locking/src/main/java/com/iluwatar/doublechecked/locking/Inventory.java
+++ b/double-checked-locking/src/main/java/com/iluwatar/doublechecked/locking/Inventory.java
@@ -12,13 +12,14 @@ import java.util.concurrent.locks.ReentrantLock;
  */
 public class Inventory {
 
-	private int inventorySize;
-	private List<Item> items;
-	private Lock lock = new ReentrantLock();
+	private final int inventorySize;
+	private final List<Item> items;
+	private final Lock lock;
 
 	public Inventory(int inventorySize) {
 		this.inventorySize = inventorySize;
-		this.items = new ArrayList<Item>(inventorySize);
+		this.items = new ArrayList<>(inventorySize);
+		this.lock = new ReentrantLock();
 	}
 
 	public boolean addItem(Item item) {
@@ -27,7 +28,9 @@ public class Inventory {
 			try {
 				if (items.size() < inventorySize) {
 					items.add(item);
-					System.out.println(Thread.currentThread());
+					System.out.println(Thread.currentThread()
+							+ ": items.size()=" + items.size()
+							+ ", inventorySize=" + inventorySize);
 					return true;
 				}
 			} finally {