HDFS-6511. BlockManager#computeInvalidateWork() could do nothing. Contributed by Juan Yu.

git-svn-id: https://svn.apache.org/repos/asf/hadoop/common/branches/branch-2@1607736 13f79535-47bb-0310-9956-ffa450edef68

hadoop-hdfs-project/hadoop-hdfs/CHANGES.txt

@@ -10,6 +10,8 @@ Release 2.6.0 - UNRELEASED
 
     HDFS-6613. Improve logging in caching classes. (wang)
 
+    HDFS-6511. BlockManager#computeInvalidateWork() could do nothing. (Juan Yu via wang)
+
   OPTIMIZATIONS
 
   BUG FIXES

hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/server/blockmanagement/BlockManager.java

@@ -1226,8 +1226,14 @@ public class BlockManager {
     nodesToProcess = Math.min(nodes.size(), nodesToProcess);
 
     int blockCnt = 0;
-    for(int nodeCnt = 0; nodeCnt < nodesToProcess; nodeCnt++ ) {
-      blockCnt += invalidateWorkForOneNode(nodes.get(nodeCnt));
+    for (DatanodeInfo dnInfo : nodes) {
+      int blocks = invalidateWorkForOneNode(dnInfo);
+      if (blocks > 0) {
+        blockCnt += blocks;
+        if (--nodesToProcess == 0) {
+          break;
+        }
+      }
     }
     return blockCnt;
   }