HDFS-8676. Delayed rolling upgrade finalization can cause heartbeat expiration. Contributed by Walter Su.

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

@@ -2090,6 +2090,9 @@ Release 2.7.2 - UNRELEASED
     HDFS-9178. Slow datanode I/O can cause a wrong node to be marked bad
     (kihwal)
 
+    HDFS-8676. Delayed rolling upgrade finalization can cause heartbeat
+    expiration. (Walter Su via kihwal)
+
 Release 2.7.1 - 2015-07-06
 
   INCOMPATIBLE CHANGES

hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/server/datanode/BlockPoolSliceStorage.java

@@ -36,6 +36,7 @@ import org.apache.hadoop.util.Daemon;
 
 import java.io.File;
 import java.io.IOException;
+import java.util.ArrayList;
 import java.util.Collection;
 import java.util.Iterator;
 import java.util.List;
@@ -92,6 +93,7 @@ public class BlockPoolSliceStorage extends Storage {
       "^(.*)(" + BLOCK_POOL_ID_PATTERN_BASE + ")(" + TRASH_ROOT_DIR + ")(.*)$");
 
   private String blockpoolID = ""; // id of the blockpool
+  private Daemon trashCleaner;
 
   public BlockPoolSliceStorage(StorageInfo storageInfo, String bpid) {
     super(storageInfo);
@@ -738,11 +740,39 @@ public class BlockPoolSliceStorage extends Storage {
    * Delete all files and directories in the trash directories.
    */
   public void clearTrash() {
+    final List<File> trashRoots = new ArrayList<>();
     for (StorageDirectory sd : storageDirs) {
       File trashRoot = getTrashRootDir(sd);
-      Preconditions.checkState(!(trashRoot.exists() && sd.getPreviousDir().exists()));
-      FileUtil.fullyDelete(trashRoot);
-      LOG.info("Cleared trash for storage directory " + sd);
+      if (trashRoot.exists() && sd.getPreviousDir().exists()) {
+        LOG.error("Trash and PreviousDir shouldn't both exist for storage "
+            + "directory " + sd);
+        assert false;
+      } else {
+        trashRoots.add(trashRoot);
+      }
+    }
+
+    stopTrashCleaner();
+    trashCleaner = new Daemon(new Runnable() {
+      @Override
+      public void run() {
+        for(File trashRoot : trashRoots){
+          FileUtil.fullyDelete(trashRoot);
+          LOG.info("Cleared trash for storage directory " + trashRoot);
+        }
+      }
+
+      @Override
+      public String toString() {
+        return "clearTrash() for " + blockpoolID;
+      }
+    });
+    trashCleaner.start();
+  }
+
+  public void stopTrashCleaner() {
+    if (trashCleaner != null) {
+      trashCleaner.interrupt();
     }
   }
 

hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/server/datanode/DataStorage.java

@@ -160,6 +160,7 @@ public class DataStorage extends Storage {
    */
   public void enableTrash(String bpid) {
     if (trashEnabledBpids.add(bpid)) {
+      getBPStorage(bpid).stopTrashCleaner();
       LOG.info("Enabled trash for bpid " + bpid);
     }
   }