diff --git a/vala/concurent_async/concurent_async.vala b/vala/concurent_async/concurent_async.vala
new file mode 100644
index 0000000..92feef1
--- /dev/null
+++ b/vala/concurent_async/concurent_async.vala
@@ -0,0 +1,44 @@
+bool called = false;
+
+async void noop() {
+}
+
+async void foo_async() {
+	if (called) {
+		stdout.puts("foo_async(): wait\n");
+		while (called)
+			yield noop();
+		return;
+	}
+	stdout.puts("foo_async(): execute\n");
+	called = true;
+	for (var i = 0; i < 100000; ++i);
+		yield noop();
+	called = false;
+}
+
+int main() {
+
+	foo_async.begin((obj, res) => {
+		foo_async.end(res);
+		stdout.puts("1'st foo_async() ended\n");
+	});
+
+
+	foo_async.begin((obj, res) => {
+		foo_async.end(res);
+		stdout.puts("2'nd foo_async() ended\n");
+	});
+
+	var loop = new MainLoop();
+
+	var t = new TimeoutSource(0);
+	t.set_callback(() => {
+		loop.quit();
+		return false;
+	});
+	t.attach(loop.get_context());
+	loop.run();
+
+	return 0;
+}
diff --git a/vala/concurent_async/run.sh b/vala/concurent_async/run.sh
new file mode 100755
index 0000000..4ef6c2f
--- /dev/null
+++ b/vala/concurent_async/run.sh
@@ -0,0 +1,3 @@
+#!/bin/bash
+
+valac --pkg=gio-2.0 concurent_async.vala && ./concurent_async