YARN-42. Modify NM's non-aggregating logs' handler to stop properly so that NMs don't get NPEs on startup errors. Contributed by Devaraj K.

git-svn-id: https://svn.apache.org/repos/asf/hadoop/common/trunk@1380954 13f79535-47bb-0310-9956-ffa450edef68

hadoop-yarn-project/CHANGES.txt

@@ -59,6 +59,9 @@ Release 2.1.0-alpha - Unreleased
     YARN-79. Implement close on all clients to YARN so that RPC clients don't
     throw exceptions on shut-down. (Vinod Kumar Vavilapalli)
 
+    YARN-42. Modify NM's non-aggregating logs' handler to stop properly so that
+    NMs don't get NPEs on startup errors. (Devaraj K via vinodkv)
+
 Release 0.23.4 - UNRELEASED
 
   INCOMPATIBLE CHANGES

hadoop-yarn-project/hadoop-yarn/hadoop-yarn-server/hadoop-yarn-server-nodemanager/src/main/java/org/apache/hadoop/yarn/server/nodemanager/containermanager/loghandler/NonAggregatingLogHandler.java

@@ -79,16 +79,18 @@ public class NonAggregatingLogHandler extends AbstractService implements
 
   @Override
   public void stop() {
-    sched.shutdown();
-    boolean isShutdown = false;
-    try {
-      isShutdown = sched.awaitTermination(10, TimeUnit.SECONDS);
-    } catch (InterruptedException e) {
-      sched.shutdownNow();
-      isShutdown = true;
-    }
-    if (!isShutdown) {
-      sched.shutdownNow();
+    if (sched != null) {
+      sched.shutdown();
+      boolean isShutdown = false;
+      try {
+        isShutdown = sched.awaitTermination(10, TimeUnit.SECONDS);
+      } catch (InterruptedException e) {
+        sched.shutdownNow();
+        isShutdown = true;
+      }
+      if (!isShutdown) {
+        sched.shutdownNow();
+      }
     }
     super.stop();
   }

hadoop-yarn-project/hadoop-yarn/hadoop-yarn-server/hadoop-yarn-server-nodemanager/src/test/java/org/apache/hadoop/yarn/server/nodemanager/containermanager/loghandler/TestNonAggregatingLogHandler.java

@@ -183,6 +183,24 @@ public class TestNonAggregatingLogHandler {
     verify(mockSched).schedule(any(Runnable.class), eq(10800l),
         eq(TimeUnit.SECONDS));
   }
+  
+  @Test
+  public void testStop() throws Exception {
+    NonAggregatingLogHandler aggregatingLogHandler = 
+        new NonAggregatingLogHandler(null, null, null);
+
+    // It should not throw NullPointerException
+    aggregatingLogHandler.stop();
+
+    NonAggregatingLogHandlerWithMockExecutor logHandler = 
+        new NonAggregatingLogHandlerWithMockExecutor(null, null, null);
+    logHandler.init(new Configuration());
+    logHandler.stop();
+    verify(logHandler.mockSched).shutdown();
+    verify(logHandler.mockSched)
+        .awaitTermination(eq(10l), eq(TimeUnit.SECONDS));
+    verify(logHandler.mockSched).shutdownNow();
+  }
 
   private class NonAggregatingLogHandlerWithMockExecutor extends
       NonAggregatingLogHandler {