MAPREDUCE-7522. Fix SpotBugs issues in hadoop-mapreduce-client-app module.

Author: slfan1989

hadoop-mapreduce-project/hadoop-mapreduce-client/hadoop-mapreduce-client-app/src/main/java/org/apache/hadoop/mapred/TaskAttemptListenerImpl.java

@@ -86,7 +86,7 @@ public class TaskAttemptListenerImpl extends CompositeService
   private Server server;
   protected TaskHeartbeatHandler taskHeartbeatHandler;
   private RMHeartbeatHandler rmHeartbeatHandler;
-  private long commitWindowMs;
+  private volatile long commitWindowMs;
   private InetSocketAddress address;
   private ConcurrentMap<WrappedJvmID, org.apache.hadoop.mapred.Task>
     jvmIDToActiveAttemptMap

hadoop-mapreduce-project/hadoop-mapreduce-client/hadoop-mapreduce-client-app/src/main/java/org/apache/hadoop/mapreduce/jobhistory/JobHistoryEventHandler.java

@@ -108,8 +108,8 @@ public class JobHistoryEventHandler extends AbstractService
   private Path stagingDirPath = null;
   private Path doneDirPrefixPath = null; // folder for completed jobs
 
-  private int maxUnflushedCompletionEvents;
-  private int postJobCompletionMultiplier;
+  private volatile int maxUnflushedCompletionEvents;
+  private volatile int postJobCompletionMultiplier;
   private long flushTimeout;
   private int minQueueSizeForBatchingFlushes; // TODO: Rename
 
@@ -121,7 +121,7 @@ public class JobHistoryEventHandler extends AbstractService
   protected BlockingQueue<JobHistoryEvent> eventQueue =
     new LinkedBlockingQueue<JobHistoryEvent>();
 
-  protected boolean handleTimelineEvent = false;
+  protected volatile boolean handleTimelineEvent = false;
   protected AsyncDispatcher atsEventDispatcher = null;
   protected Thread eventHandlingThread;
 

hadoop-mapreduce-project/hadoop-mapreduce-client/hadoop-mapreduce-client-app/src/main/java/org/apache/hadoop/mapreduce/v2/app/MRAppMaster.java

@@ -233,13 +233,13 @@ public class MRAppMaster extends CompositeService {
   @VisibleForTesting
   protected volatile boolean isLastAMRetry = false;
   //Something happened and we should shut down right after we start up.
-  boolean errorHappenedShutDown = false;
+  volatile boolean errorHappenedShutDown = false;
   private String shutDownMessage = null;
   JobStateInternal forcedState = null;
   private final ScheduledExecutorService logSyncer;
 
-  private long recoveredJobStartTime = -1L;
-  private static boolean mainStarted = false;
+  private volatile long recoveredJobStartTime = -1L;
+  private static volatile boolean mainStarted = false;
 
   @VisibleForTesting
   protected AtomicBoolean successfullyUnregistered =