HBASE-4473 NPE when executors are down but events are still coming in

git-svn-id: https://svn.apache.org/repos/asf/hbase/trunk@1178520 13f79535-47bb-0310-9956-ffa450edef68

CHANGES.txt

@@ -689,6 +689,7 @@ Release 0.90.5 - Unreleased
    HBASE-4295  rowcounter does not return the correct number of rows in
                certain circumstances (David Revell)
    HBASE-4515  User.getCurrent() can fail to initialize the current user
+   HBASE-4473  NPE when executors are down but events are still coming in
 
   IMPROVEMENT
    HBASE-4205  Enhance HTable javadoc (Eric Charles)

src/main/java/org/apache/hadoop/hbase/executor/ExecutorService.java

@@ -213,9 +213,6 @@ public class ExecutorService {
 
   Executor getExecutor(String name) {
     Executor executor = this.executorMap.get(name);
-    if (executor == null) {
-      LOG.debug("Executor service [" + name + "] not found in " + this.executorMap);
-    }
     return executor;
   }
 
@@ -231,7 +228,16 @@ public class ExecutorService {
   }
 
   public void submit(final EventHandler eh) {
-    getExecutor(getExecutorServiceType(eh.getEventType())).submit(eh);
+    Executor executor = getExecutor(getExecutorServiceType(eh.getEventType()));
+    if (executor == null) {
+      // This happens only when events are submitted after shutdown() was
+      // called, so dropping them should be "ok" since it means we're
+      // shutting down.
+      LOG.error("Cannot submit [" + eh + "] because the executor is missing." +
+        " Is this process shutting down?");
+    } else {
+      executor.submit(eh);
+    }
   }
 
   /**

src/test/java/org/apache/hadoop/hbase/executor/TestExecutorService.java

@@ -124,6 +124,15 @@ public class TestExecutorService {
     // Make sure threads are still around even after their timetolive expires.
     Thread.sleep(executor.keepAliveTimeInMillis * 2);
     assertEquals(maxThreads, pool.getPoolSize());
+
+    executorService.shutdown();
+
+    assertEquals(0, executorService.getAllExecutorStatuses().size());
+
+    // Test that submit doesn't throw NPEs
+    executorService.submit(
+      new TestEventHandler(mockedServer, EventType.M_SERVER_SHUTDOWN,
+            lock, counter));
   }
 
   private void checkStatusDump(ExecutorStatus status) throws IOException {