A simple deadlock in java with 2 threads

Author: rampatra

src/main/java/com/rampatra/threads/SimpleDeadlock.java

@@ -0,0 +1,56 @@
+package com.rampatra.threads;
+
+
+import java.lang.management.ManagementFactory;
+import java.lang.management.ThreadMXBean;
+
+/**
+ * @author rampatra
+ * @since 2019-03-13
+ */
+public class SimpleDeadlock implements Runnable {
+
+    private final Object obj1;
+    private final Object obj2;
+
+    private SimpleDeadlock(Object obj1, Object obj2) {
+        this.obj1 = obj1;
+        this.obj2 = obj2;
+    }
+
+    public void run() {
+        try {
+            synchronized (obj1) {
+                // sleep for some time so that the next thread starts and acquires the other lock in the mean time
+                Thread.sleep(5000);
+                synchronized (obj2) {
+                    System.out.println("No deadlock!");
+                }
+            }
+        } catch (InterruptedException e) {
+            throw new RuntimeException(e);
+        }
+    }
+
+    public static void main(String[] args) {
+
+        Object obj1 = new Object();
+        Object obj2 = new Object();
+
+        Thread thread1 = new Thread(new SimpleDeadlock(obj1, obj2));
+        Thread thread2 = new Thread(new SimpleDeadlock(obj2, obj1));
+
+        thread1.start();
+        thread2.start();
+
+        // a way to detect deadlocks, although an expensive one
+        ThreadMXBean threadMXBean = ManagementFactory.getThreadMXBean();
+        while (true) {
+            long[] deadlock = threadMXBean.findDeadlockedThreads();
+            if (deadlock != null && deadlock.length > 0) {
+                System.out.println("Deadlock detected, exiting now...");
+                System.exit(1);
+            }
+        }
+    }
+}