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From "dhruba Borthakur" <dhr...@yahoo-inc.com>
Subject RE: secondary namenode web interface
Date Tue, 08 Apr 2008 17:20:04 GMT
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:yuri@isi.edu] 
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:yuri@isi.edu]
> 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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