HBASE-3914 ROOT region appeared in two regionserver's onlineRegions at the same time

git-svn-id: https://svn.apache.org/repos/asf/hbase/trunk@1127158 13f79535-47bb-0310-9956-ffa450edef68

CHANGES.txt

@@ -285,6 +285,8 @@ Release 0.90.4 - Unreleased
    HBASE-3908  TableSplit not implementing "hashCode" problem (Daniel Iancu)
    HBASE-3915  Binary row keys in hbck and other miscellaneous binary key
                display issues
+   HBASE-3914  ROOT region appeared in two regionserver's onlineRegions at
+               the same time (Jieshan Bean)
 
   IMPROVEMENT
    HBASE-3882  hbase-config.sh needs to be updated so it can auto-detects the

src/main/java/org/apache/hadoop/hbase/master/handler/ServerShutdownHandler.java

@@ -73,6 +73,26 @@ public class ServerShutdownHandler extends EventHandler {
     }
   }
 
+  /**
+   * Before assign the ROOT region, ensure it haven't 
+   *  been assigned by other place
+   * <p>
+   * Under some scenarios, the ROOT region can be opened twice, so it seemed online
+   * in two regionserver at the same time.
+   * If the ROOT region has been assigned, so the operation can be canceled. 
+   * @throws InterruptedException
+   * @throws IOException
+   * @throws KeeperException
+   */
+  private void verifyAndAssignRoot() 
+  throws InterruptedException, IOException, KeeperException {
+    long timeout = this.server.getConfiguration().
+      getLong("hbase.catalog.verification.timeout", 1000);
+    if (!this.server.getCatalogTracker().verifyRootRegionLocation(timeout)) {
+      this.services.getAssignmentManager().assignRoot();     
+    }
+  }
+  
   /**
    * @return True if the server we are processing was carrying <code>-ROOT-</code>
    */
@@ -104,10 +124,14 @@ public class ServerShutdownHandler extends EventHandler {
     // Assign root and meta if we were carrying them.
     if (isCarryingRoot()) { // -ROOT-
       try {
-        this.services.getAssignmentManager().assignRoot();
+        verifyAndAssignRoot();
       } catch (KeeperException e) {
         this.server.abort("In server shutdown processing, assigning root", e);
         throw new IOException("Aborting", e);
+      } catch (InterruptedException e1) {
+        LOG.warn("Interrupted while verifying root region's location", e1);
+        Thread.currentThread().interrupt();
+        throw new IOException(e1);  
       }
     }
 
@@ -312,4 +336,4 @@ public class ServerShutdownHandler extends EventHandler {
       return false;
     }
   }
-}
+}