Re: secondary namenode web interface

Tue, 08 Apr 2008 11:55:25 -0700 

Yuri,

The NullPointerException should be fixed as Dhruba proposed.
We do not have any secondary nn web interface as of today.
The http server is used for transferring data between the primary and the 
secondary.
I don't see we can display anything useful on the secondary web UI except for 
the
current status, config values, and the last checkpoint date/time.
If you have anything in mind that can be displayed on the UI please let us know.
You can also find a jira for the issue, it would be good if this discussion
is reflected in it.

Thanks,
--Konstantin

dhruba Borthakur wrote:

The secondary Namenode uses the HTTP interface to pull the fsimage from
the primary. Similarly, the primary Namenode uses the
dfs.secondary.http.address to pull the checkpointed-fsimage back from
the secondary to the primary. So, the definition of
dfs.secondary.http.address is needed.

However, the servlet dfshealth.jsp should not be served from the
secondary Namenode. This servet should be setup in such a way that only
the primary Namenode invokes this servlet.

Thanks,
dhruba

-----Original Message-----
From: Yuri Pradkin [mailto:[EMAIL PROTECTED] Sent: Tuesday, April 08, 2008 10:11 AM 
To: core-user@hadoop.apache.org
Subject: Re: secondary namenode web interface

I'd be happy to file a JIRA for the bug, I just want to make sure I
understand what the bug is: is it the misleading "null pointer" message or is it that someone is listening on this port and not doing anything useful? I 
mean,
what is the configuration parameter dfs.secondary.http.address for?
Unless there are plans to make this interface work, this config parameter should go away, and so should the listening thread, shouldn't they? 

Thanks,
  -Yuri

On Friday 04 April 2008 03:30:46 pm dhruba Borthakur wrote:


Your configuration is good. The secondary Namenode does not publish a
web interface. The "null pointer" message in the secondary Namenode


log


is a harmless bug but should be fixed. It would be nice if you can


open


a JIRA for it.

Thanks,
Dhruba


-----Original Message-----
From: Yuri Pradkin [mailto:[EMAIL PROTECTED]
Sent: Friday, April 04, 2008 2:45 PM
To: core-user@hadoop.apache.org
Subject: Re: secondary namenode web interface

I'm re-posting this in hope that someone would help.  Thanks!

On Wednesday 02 April 2008 01:29:45 pm Yuri Pradkin wrote:


Hi,

I'm running Hadoop (latest snapshot) on several machines and in our


setup



namenode and secondarynamenode are on different systems.  I see from


the



logs than secondary namenode regularly checkpoints fs from primary
namenode.

But when I go to the secondary namenode HTTP


(dfs.secondary.http.address)



in my browser I see something like this:

        HTTP ERROR: 500
        init
        RequestURI=/dfshealth.jsp
        Powered by Jetty://

And in secondary's log I find these lines:

2008-04-02 11:26:25,357 WARN /: /dfshealth.jsp:
java.lang.NullPointerException
       at
org.apache.hadoop.dfs.dfshealth_jsp.<init>(dfshealth_jsp.java:21) at
sun.reflect.NativeConstructorAccessorImpl.newInstance0(Native


Method)


at




sun.reflect.NativeConstructorAccessorImpl.newInstance(NativeConstructorA


cce



ssorImpl.java:57) at




sun.reflect.DelegatingConstructorAccessorImpl.newInstance(DelegatingCons


tru



ctorAccessorImpl.java:45) at
java.lang.reflect.Constructor.newInstance(Constructor.java:539) at
java.lang.Class.newInstance0(Class.java:373)
       at java.lang.Class.newInstance(Class.java:326)
       at


org.mortbay.jetty.servlet.Holder.newInstance(Holder.java:199)



       at




org.mortbay.jetty.servlet.ServletHolder.getServlet(ServletHolder.java:32


6)



at


org.mortbay.jetty.servlet.ServletHolder.handle(ServletHolder.java:405)



at




org.mortbay.jetty.servlet.WebApplicationHandler.dispatch(WebApplicationH


and



ler.java:475) at




org.mortbay.jetty.servlet.ServletHandler.handle(ServletHandler.java:567)


at



org.mortbay.http.HttpContext.handle(HttpContext.java:1565) at




org.mortbay.jetty.servlet.WebApplicationContext.handle(WebApplicationCon


tex



t.java:635) at


org.mortbay.http.HttpContext.handle(HttpContext.java:1517) at



org.mortbay.http.HttpServer.service(HttpServer.java:954) at
org.mortbay.http.HttpConnection.service(HttpConnection.java:814) at
org.mortbay.http.HttpConnection.handleNext(HttpConnection.java:981)


at


org.mortbay.http.HttpConnection.handle(HttpConnection.java:831) at




org.mortbay.http.SocketListener.handleConnection(SocketListener.java:244


)



at org.mortbay.util.ThreadedServer.handle(ThreadedServer.java:357)


at


org.mortbay.util.ThreadPool$PoolThread.run(ThreadPool.java:534)

Is something missing from my configuration?  Anybody else seen


these?


Thanks,

 -Yuri

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