improvement: Optimized NioReactor stop() (Reactor Pattern) (#1930)

* Optimized NioReactor stop()

* Optimized ThreadPoolDispatcher stop()

reactor/src/main/java/com/iluwatar/reactor/framework/NioReactor.java

@@ -96,9 +96,11 @@ public class NioReactor {
    * @throws IOException          if any I/O error occurs.
    */
   public void stop() throws InterruptedException, IOException {
-    reactorMain.shutdownNow();
+    reactorMain.shutdown();
     selector.wakeup();
-    reactorMain.awaitTermination(4, TimeUnit.SECONDS);
+    if (!reactorMain.awaitTermination(4, TimeUnit.SECONDS)) {
+      reactorMain.shutdownNow();
+    }
     selector.close();
     LOGGER.info("Reactor stopped");
   }

reactor/src/main/java/com/iluwatar/reactor/framework/ThreadPoolDispatcher.java

@@ -64,6 +64,8 @@ public class ThreadPoolDispatcher implements Dispatcher {
   @Override
   public void stop() throws InterruptedException {
     executorService.shutdown();
-    executorService.awaitTermination(4, TimeUnit.SECONDS);
+    if (executorService.awaitTermination(4, TimeUnit.SECONDS)) {
+      executorService.shutdownNow();
+    }
   }
 }