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From Yabo Xu <arber.resea...@gmail.com>
Subject Re: Is NotServingRegionException really an Exception?
Date Thu, 01 Apr 2010 01:35:36 GMT
Thanks, J-D. I will do it next time I catch this.

Best,
Arber

On Thu, Apr 1, 2010 at 12:56 AM, Jean-Daniel Cryans <jdcryans@apache.org>wrote:

> Arber,
>
> If your cluster doesn't recover, it means there's something else going
> on. Feel free to start a new thread on this mailing list to discuss
> that, posting relevant informations like version, hardware,
> configurations and logs.
>
> J-D
>
> On Wed, Mar 31, 2010 at 9:39 AM, Yabo Xu <arber.research@gmail.com> wrote:
> > Sorry for interrupting the thread. We also gets the annoying
> > NotServingRegionException once in a while ( especially after intensive
> > writing), and if it happens, it seems that the only way is to stop all
> the
> > programs and restart HBase.
> >
> > Any better way to deal with it?  ( I tried flush operation on the shell,
> but
> > it does not work )
> >
> > Or how to avoid this from happening?
> >
> > Thanks,
> > Arber
> >
> > On Wed, Mar 31, 2010 at 11:44 PM, Stack <stack@duboce.net> wrote:
> >
> >> I always thought that the throwing of an exception to signal moved
> >> region was broke if only for the reason that it disturbing to new
> >> users.  See https://issues.apache.org/jira/browse/HBASE-72
> >>
> >> Would be nice to change it.  I don't think it easy though.  We'd need
> >> to rig the RPC so calls were enveloped or some such so we could pass
> >> status messages along with (or instead of) a query results.
> >>
> >> St.Ack
> >>
> >>
> >> On Wed, Mar 31, 2010 at 8:06 AM, Edward Capriolo <edlinuxguru@gmail.com
> >
> >> wrote:
> >> > On Wed, Mar 31, 2010 at 11:02 AM, Gary Helmling <ghelmling@gmail.com>
> >> wrote:
> >> >
> >> >> Well I would still view it as an exceptional condition.  The client
> >> asked
> >> >> for data back from a server that does not own that data.  Sending
> back
> >> an
> >> >> exception seems like the appropriate response, to me at least.  It's
> >> just
> >> >> an
> >> >> exceptional condition that's allowed to happen in favor of the
> >> optimization
> >> >> of caching region locations in memory on the client.
> >> >>
> >> >> I could see the reporting of the exception being misleading though
if
> >> it's
> >> >> being logged at an error or warn level when it's a normal part of
> >> >> operations.  What's the logging level of the messages?
> >> >>
> >> >>
> >> >> On Wed, Mar 31, 2010 at 10:51 AM, Al Lias <al.lias@gmx.de> wrote:
> >> >>
> >> >> > Am 31.03.2010 16:47, schrieb Gary Helmling:
> >> >> > > NotServingRegionException is a normal part of operations
when
> >> regions
> >> >> > > transition (ie due to splits).  It's how the region server
> signals
> >> back
> >> >> > to
> >> >> > > the client that it needs to re-lookup the region location
in
> .META.
> >> >> > (which
> >> >> > > is normally cached in memory by the client, so can become
stale).
> >> >> > >
> >> >> > > I'm sure it can also show up as a symptom of other problems,
but
> if
> >> >> > you're
> >> >> > > not seeing any other issues, then it's nothing to be concerned
> >> about.
> >> >> > >
> >> >> >
> >> >> > Thx Gary,
> >> >> >
> >> >> >        this is my point: I see this many times in the (production)
> >> logs
> >> >> > when
> >> >> > it is actually nothing to worry about. Should'nt this rather be
a
> >> normal
> >> >> > response of a region server, instead an Exception?
> >> >> >
> >> >> > Al
> >> >> >
> >> >> > >
> >> >> > > On Wed, Mar 31, 2010 at 7:38 AM, Al Lias <al.lias@gmx.de>
wrote:
> >> >> > >
> >> >> > >> As I do see this Exception really often in our logs.
I wonder if
> >> this
> >> >> > >> indicates a regular thing (within splits etc) or if this
is
> >> something
> >> >> > >> that should not normally happen.
> >> >> > >>
> >> >> > >> I see it often in Jira as a reason for something else
that
> fails,
> >> but
> >> >> > >> for a regular client request, where the client not perfectly
> >> >> up-to-date
> >> >> > >> with region information it looks as something normal.
Am I right
> >> here?
> >> >> > >>
> >> >> > >>
> >> >> > >> Al
> >> >> > >>
> >> >> > >
> >> >> >
> >> >> >
> >> >>
> >> > The LDAP api's throw a ReferralException when you try to update a read
> >> only
> >> > slave, so heir is a precedence for that. But true that an exception
> may
> >> be
> >> > strong for something that is technically a warning.
> >> >
> >>
> >
>

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