[HDFS-2567] When 0 DNs are available, show a proper error when trying to browse DFS via web UI

• Type: Bug
• Status: Closed
• Priority: Major
• Resolution: Fixed
• Affects Version/s: 0.23.0
• Fix Version/s: 0.23.1
• Component/s: namenode
• Hadoop Flags: Reviewed
• Assignee: Harsh J
• Reporter: Harsh J
• Created: 19/Nov/11 14:26
• Updated: 05/Mar/12 02:49
• Resolved: 20/Nov/11 06:29

Description

Trace:

HTTP ERROR 500

Problem accessing /nn_browsedfscontent.jsp. Reason:

    n must be positive
Caused by:

java.lang.IllegalArgumentException: n must be positive
	at java.util.Random.nextInt(Random.java:250)
	at org.apache.hadoop.net.NetworkTopology.chooseRandom(NetworkTopology.java:556)
	at org.apache.hadoop.net.NetworkTopology.chooseRandom(NetworkTopology.java:524)
	at org.apache.hadoop.hdfs.server.namenode.NamenodeJspHelper.getRandomDatanode(NamenodeJspHelper.java:372)
	at org.apache.hadoop.hdfs.server.namenode.NamenodeJspHelper.redirectToRandomDataNode(NamenodeJspHelper.java:383)
	at org.apache.hadoop.hdfs.server.namenode.nn_005fbrowsedfscontent_jsp._jspService(nn_005fbrowsedfscontent_jsp.java:70)
	at org.apache.jasper.runtime.HttpJspBase.service(HttpJspBase.java:98)
	at javax.servlet.http.HttpServlet.service(HttpServlet.java:820)
	at org.mortbay.jetty.servlet.ServletHolder.handle(ServletHolder.java:511)
	at org.mortbay.jetty.servlet.ServletHandler$CachedChain.doFilter(ServletHandler.java:1221)
	at org.apache.hadoop.http.lib.StaticUserWebFilter$StaticUserFilter.doFilter(StaticUserWebFilter.java:109)
	at org.mortbay.jetty.servlet.ServletHandler$CachedChain.doFilter(ServletHandler.java:1212)
	at org.apache.hadoop.http.HttpServer$QuotingInputFilter.doFilter(HttpServer.java:940)
	at org.mortbay.jetty.servlet.ServletHandler$CachedChain.doFilter(ServletHandler.java:1212)
	at org.mortbay.jetty.servlet.ServletHandler.handle(ServletHandler.java:399)
	at org.mortbay.jetty.security.SecurityHandler.handle(SecurityHandler.java:216)
	at org.mortbay.jetty.servlet.SessionHandler.handle(SessionHandler.java:182)
	at org.mortbay.jetty.handler.ContextHandler.handle(ContextHandler.java:766)
	at org.mortbay.jetty.webapp.WebAppContext.handle(WebAppContext.java:450)
	at org.mortbay.jetty.handler.ContextHandlerCollection.handle(ContextHandlerCollection.java:230)
	at org.mortbay.jetty.handler.HandlerWrapper.handle(HandlerWrapper.java:152)
	at org.mortbay.jetty.Server.handle(Server.java:326)
	at org.mortbay.jetty.HttpConnection.handleRequest(HttpConnection.java:542)
	at org.mortbay.jetty.HttpConnection$RequestHandler.headerComplete(HttpConnection.java:928)
	at org.mortbay.jetty.HttpParser.parseNext(HttpParser.java:549)
	at org.mortbay.jetty.HttpParser.parseAvailable(HttpParser.java:212)
	at org.mortbay.jetty.HttpConnection.handle(HttpConnection.java:404)
	at org.mortbay.io.nio.SelectChannelEndPoint.run(SelectChannelEndPoint.java:410)
	at org.mortbay.thread.QueuedThreadPool$PoolThread.run(QueuedThreadPool.java:582)

Steps I did to run into this:

1. Start a new NN, freshly formatted.
2. No DNs yet.
3. Visit the DFS browser link http://localhost:50070/nn_browsedfscontent.jsp
4. Above error shows itself
5. hdfs dfs -touchz afile
6. Re-visit, still shows the same issue.

Perhaps its cause of no added DN so far.