HADOOP-1205. Improve synchronization around HDFS block map. Contributed by Hairong.

git-svn-id: https://svn.apache.org/repos/asf/lucene/hadoop/trunk@538314 13f79535-47bb-0310-9956-ffa450edef68

CHANGES.txt

@@ -392,6 +392,9 @@ Branch 0.13 (unreleased changes)
 112. HADOOP-1345.  Fix HDFS to correctly retry another replica when a
      checksum error is encountered.  (Hairong Kuang via cutting)
 
+113. HADOOP-1205.  Improve synchronization around HDFS block map.
+     (Hairong Kuang via cutting)
+
 
 Release 0.12.3 - 2007-04-06
 

src/java/org/apache/hadoop/dfs/FSNamesystem.java

@@ -433,7 +433,7 @@ class FSNamesystem implements FSConstants {
    * The client should choose one of the machines from the machineArray
    * at random.
    */
-  public Object[] open(String clientMachine, UTF8 src) {
+  synchronized public Object[] open(String clientMachine, UTF8 src) {
     Object results[] = null;
     Block blocks[] = dir.getFile(src);
     if (blocks != null) {