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From Edward Capriolo <edlinuxg...@gmail.com>
Subject Re: Is NotServingRegionException really an Exception?
Date Wed, 31 Mar 2010 15:06:34 GMT
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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