svn merge -c 1360448 FIXES: HADOOP-8587. HarFileSystem access of harMetaCache isn't threadsafe. Contributed by Eli Collins

git-svn-id: https://svn.apache.org/repos/asf/hadoop/common/branches/branch-0.23@1360738 13f79535-47bb-0310-9956-ffa450edef68

hadoop-common-project/hadoop-common/CHANGES.txt

@@ -109,6 +109,8 @@ Release 0.23.3 - UNRELEASED
     EOFException on Snappy or LZO block-compressed data
     (todd via harsh)
 
+    HADOOP-8587. HarFileSystem access of harMetaCache isn't threadsafe. (eli)
+
 Release 0.23.2 - UNRELEASED 
 
   NEW FEATURES

hadoop-common-project/hadoop-common/src/main/java/org/apache/hadoop/fs/HarFileSystem.java

@@ -24,11 +24,11 @@ import java.net.URI;
 import java.net.URISyntaxException;
 import java.net.URLDecoder;
 import java.util.ArrayList;
-import java.util.EnumSet;
 import java.util.List;
 import java.util.Map;
 import java.util.TreeMap;
 import java.util.HashMap;
+import java.util.concurrent.ConcurrentHashMap;
 
 import org.apache.hadoop.conf.Configuration;
 import org.apache.hadoop.fs.permission.FsPermission;
@@ -52,7 +52,8 @@ import org.apache.hadoop.util.Progressable;
 public class HarFileSystem extends FilterFileSystem {
   public static final int VERSION = 3;
 
-  private static final Map<URI, HarMetaData> harMetaCache = new HashMap<URI, HarMetaData>();
+  private static final Map<URI, HarMetaData> harMetaCache =
+      new ConcurrentHashMap<URI, HarMetaData>();
 
   // uri representation of this Har filesystem
   private URI uri;
@@ -1043,7 +1044,7 @@ public class HarFileSystem extends FilterFileSystem {
       FileStatus archiveStat = fs.getFileStatus(archiveIndexPath);
       archiveIndexTimestamp = archiveStat.getModificationTime();
       LineReader aLin;
-      String retStr = null;
+
       // now start reading the real index file
       for (Store s: stores) {
         read = 0;