Disable caching for JarURLConnection to avoid sharing JarFile with ot…

…her users when loading resource from URL in Configuration class. Contributed by Zhihai Xu

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

@@ -782,6 +782,10 @@ Release 2.8.0 - UNRELEASED
     HADOOP-12413. AccessControlList should avoid calling getGroupNames in
     isUserInList with empty groups. (Zhihai Xu via cnauroth)
 
+    HADOOP-12404. Disable caching for JarURLConnection to avoid sharing
+    JarFile with other users when loading resource from URL in Configuration
+    class. (zxu)
+
   OPTIMIZATIONS
 
     HADOOP-11785. Reduce the number of listStatus operation in distcp

hadoop-common-project/hadoop-common/src/main/java/org/apache/hadoop/conf/Configuration.java

@@ -34,7 +34,9 @@
 import java.io.Writer;
 import java.lang.ref.WeakReference;
 import java.net.InetSocketAddress;
+import java.net.JarURLConnection;
 import java.net.URL;
+import java.net.URLConnection;
 import java.util.ArrayList;
 import java.util.Arrays;
 import java.util.Collection;
@@ -2531,7 +2533,14 @@ private Document parse(DocumentBuilder builder, URL url)
     if (url == null) {
       return null;
     }
-    return parse(builder, url.openStream(), url.toString());
+
+    URLConnection connection = url.openConnection();
+    if (connection instanceof JarURLConnection) {
+      // Disable caching for JarURLConnection to avoid sharing JarFile
+      // with other users.
+      connection.setUseCaches(false);
+    }
+    return parse(builder, connection.getInputStream(), url.toString());
   }
 
   private Document parse(DocumentBuilder builder, InputStream is,