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HBase, mail # user - Coprocessor / threading model


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Re: Coprocessor / threading model
Ted Yu 2013-01-13, 02:48
bq. Coprocessors are meant to operate on the region to which they are
associated.

For Anoop's case, the secondary table(s) have their regions aligned with
the corresponding region from primary table. Meaning, related regions are
served by the same region server.
Would writes to such regions of secondary table(s) be acceptable ?

Thanks

On Sat, Jan 12, 2013 at 6:39 PM, Andrew Purtell <[EMAIL PROTECTED]> wrote:

> > In pre-put, I trigger another Put() in an external table (to build the
> secondary index).
>
> We should probably call this a Coprocessor anti-pattern.
>
> Coprocessors are meant to operate on the region to which they are
> associated. They are a way you can extend HBase function while it operates
> in region on data for the region. Think of them as loadable kernel modules.
> They are not a general purpose server side platform for programming as if
> you are building a HBase client (with HTable, etc.). Just because you can
> do this doesn't mean you should.
>
>
> On Sat, Jan 12, 2013 at 4:06 PM, Adrien Mogenet <[EMAIL PROTECTED]
> >wrote:
>
> > Hi there,
> >
> > I'm experiencing some issues with CP. I'm trying to implement an indexing
> > solution (inspired by Annop's slides). In pre-put, I trigger another
> Put()
> > in an external table (to build the secondary index). It works perfect for
> > one client, but when I'm inserting data from 2 separate clients, I met
> > issues with HTable object (the one used in pre-Put()), because it's not
> > thread-safe. I decided to move on TablePool and that fixed my issue.
> >
> > But if I increase the write-load (and concurrency) HBase is throwing a
> OOM
> > exception because it can't create new native threads. Looking at HBase
> > metrics "threads count", I see that roughly 3500 threads are created.
> >
> > I'm looking for documentation about how CPs are working with threads :
> > what/when should I protect against concurrency issues ? How may I solve
> my
> > issue ?
> >
> > Help is welcome :-)
> >
> > --
> > Adrien Mogenet
> > 06.59.16.64.22
> > http://www.mogenet.me
> >
>
>
>
> --
> Best regards,
>
>    - Andy
>
> Problems worthy of attack prove their worth by hitting back. - Piet Hein
> (via Tom White)
>