PR comments

Author: abstractdog

tez-common/src/main/java/org/apache/tez/util/TezRuntimeShutdownHandler.java

@@ -23,11 +23,14 @@
 import org.slf4j.Logger;
 import org.slf4j.LoggerFactory;
 
-public class TezRuntimeShutdownHandler {
+public final class TezRuntimeShutdownHandler {
   private static final Logger LOG = LoggerFactory.getLogger(TezRuntimeShutdownHandler.class);
 
   private static final List<Runnable> shutdownTasks = new ArrayList<>();
 
+  private TezRuntimeShutdownHandler() {
+  }
+
   public static void addShutdownTask(Runnable r) {
     shutdownTasks.add(r);
   }

tez-runtime-library/src/main/java/org/apache/tez/http/async/netty/AsyncHttpConnection.java

@@ -103,15 +103,16 @@ private void initClient(HttpConnectionParams httpConnParams) throws IOException
               .build();
           DefaultAsyncHttpClientConfig config = builder.build();
           httpAsyncClient = new DefaultAsyncHttpClient(config);
-          TezRuntimeShutdownHandler.addShutdownTask(new Thread(() -> {
+          TezRuntimeShutdownHandler.addShutdownTask(() -> {
             try {
               if (httpAsyncClient != null) {
                 httpAsyncClient.close();
+                httpAsyncClient = null;
               }
             } catch (IOException e) {
               LOG.warn("Error while closing async client (this won't block shutdown)", e);
             }
-          }));
+          });
         }
       }
     }