diff --git a/vala/threads/class.vala b/vala/threads/class.vala
index 7f38c81..ec7dea8 100644
--- a/vala/threads/class.vala
+++ b/vala/threads/class.vala
@@ -1,4 +1,4 @@
-public class MyThread {
+public class MyThread : Object {
 
 	private string _s;
 
@@ -8,7 +8,9 @@ public class MyThread {
 
 	public int run () {
 		stdout.printf ("%s\n", _s);
+		//Thread.usleep(3000000);
 		return 0;
+		//Thread.exit (0); // the same
 	}
 }
 
diff --git a/vala/threads/lock.vala b/vala/threads/lock.vala
new file mode 100644
index 0000000..8b4b684
--- /dev/null
+++ b/vala/threads/lock.vala
@@ -0,0 +1,34 @@
+public class MyThread : Object {
+
+	public int lock_var = 0;
+
+	public int increase_lock_var () {
+		var ret = 0;
+		lock (lock_var) ret = ++lock_var;
+		return ret;
+	}
+
+	public int run () {
+
+		for (var i = 0; i < 8; ++i) {
+			var tmp = 0;
+			lock (lock_var) tmp = lock_var++;
+			stdout.puts (@"thrd:$lock_var\n");
+			Thread.usleep(100);
+		}
+		return 0;
+	}
+}
+
+void main () {
+	var mt = new MyThread ();
+	var t = new Thread<int> ("Debugging thread name", mt.run);
+
+	for (var i = 0; i < 8; ++i) {
+		var tmp = mt.increase_lock_var ();
+		stdout.puts(@"main:$tmp\n");
+		Thread.usleep(100);
+	}
+
+	t.join ();
+}