Dealock code added.

src/test/java/org/chulk/sanxbox/TestConcurrency.java

@@ -1,5 +1,70 @@
 package org.chulk.sanxbox;
 
+import org.junit.jupiter.api.Test;
+
 public class TestConcurrency {
 
+	private int counter = 0;
+	private final Object lock1 = new Object();
+	private final Object lock2 = new Object();
+
+	@Test
+	public void testDeadlock() throws InterruptedException {
+		Runnable incRun = () -> {
+			try {
+                for (int i = 0; i < 100; i++) {
+                    incrementCounter();
+                    System.out.println("Incrementing " + i);
+                }
+            } catch (InterruptedException ie) {
+            }
+		};
+
+		Runnable decRun = () -> {
+			try {
+                for (int i = 0; i < 100; i++) {
+                	decrementCounter();
+                    System.out.println("Decrementing " + i);
+                }
+            } catch (InterruptedException ie) {
+            }
+		};
+
+		Thread thread1 = new Thread(incRun);
+		Thread thread2 = new Thread(decRun);
+
+		thread1.start();
+		// sleep to make sure thread 1 gets a chance to acquire lock1
+		Thread.sleep(100);
+		thread2.start();
+
+		thread1.join();
+		thread2.join();
+
+		System.out.println("Done : " + counter);
+
+	}
+
+	void incrementCounter() throws InterruptedException {
+		synchronized (lock1) {
+			System.out.println("Acquired lock1");
+			Thread.sleep(100);
+
+			synchronized (lock2) {
+				counter++;
+			}
+		}
+	}
+
+	void decrementCounter() throws InterruptedException {
+		synchronized (lock2) {
+			System.out.println("Acquired lock2");
+
+			Thread.sleep(100);
+			synchronized (lock1) {
+				counter--;
+			}
+		}
+	}
+
 }