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HBase >> mail # dev >> Heads up, HTablePool will be deprecated in 0.94, 0.95/0.96, and removed in 0.98


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Re: Heads up, HTablePool will be deprecated in 0.94, 0.95/0.96, and removed in 0.98
Correct. No more guessing about what might happen behind the scenes.

________________________________
 From: Ted Yu <[EMAIL PROTECTED]>
To: lars hofhansl <[EMAIL PROTECTED]>
Cc: "[EMAIL PROTECTED]" <[EMAIL PROTECTED]>
Sent: Sunday, August 4, 2013 8:08 PM
Subject: Re: Heads up, HTablePool will be deprecated in 0.94, 0.95/0.96, and removed in 0.98
 

w.r.t. HConstants.HBASE_CLIENT_PAUSE in #3, if user wants a different
pause, a new connection would be created explicitly in the new model, right
?

Cheers

On Sun, Aug 4, 2013 at 7:56 PM, lars hofhansl <[EMAIL PROTECTED]> wrote:

> Let's do a little quiz:
>
> HTable t1 = new HTable(conf);
> t1.close();
>
> // 1. Will the next line create a new HConnection behind the scenes (along
> with re-creating all the caches)?
> // (If so, it will be expensive, if not, when is the first HConnection
> actually released?)
> HTable t2 = new HTable(conf);
>
> // 2. how about this one?
> HTable t2 = new HTable(new Configuration(conf));
>
> // 3. or now?
> conf.setInt(HConstants.HBASE_CLIENT_PAUSE, 2000);
> HTable t3 = new HTable(conf);
>
> // 4. and now?
> conf.setInt(HBASE_CLIENT_SCANNER_MAX_RESULT_SIZE_KEY, 1024000);
> HTable t4 = new HTable(conf);
>
> // 5. how many connections are opened now?
> t4.close();
>
> This stuff is convoluted and needlessly complicated. And this is not
> because the code is bad, but because the abstraction is simply inadequate.
> A client wants to connect to a cluster and then do some action on that
> cluster (via HTable as a convenience).
> If the cluster connection is implicit it leads to all of the above
> considerations.
>
> (#1: Yes, #2: no, #3: yes, #4: no, #5: I don't really know, id'd have run
> it to see)
>
> -- Lars
>
>
>
>   ------------------------------
>  *From:* Ted Yu <[EMAIL PROTECTED]>
> *To:* lars hofhansl <[EMAIL PROTECTED]>
> *Cc:* "[EMAIL PROTECTED]" <[EMAIL PROTECTED]>
> *Sent:* Sunday, August 4, 2013 7:39 PM
>
> *Subject:* Re: Heads up, HTablePool will be deprecated in 0.94,
> 0.95/0.96, and removed in 0.98
>
> In the Connections "managing" HTables case, don't we need to figure out
> when an HConnection should be released ?
>
> On Sun, Aug 4, 2013 at 7:23 PM, lars hofhansl <[EMAIL PROTECTED]> wrote:
>
> Just look at HConnectionKey part, and hoops we go through to detect
> whether HConnections are the same or not, when to cache them, when/how to
> release them.
> In fact almost all HConnectionManager does is managing HConnections on
> behalf of HTable, when it should be other way around.
>
> Typically, when things get hard to explain (check out the comments in
> HConnectionManager) there is either an abstraction missing, or the
> abstraction is not right.
> The reverse (Connections "managing" HTables) has none of this.
>
>
> -- Lars
>
> _______________________________
> From: Ted Yu <[EMAIL PROTECTED]>
> To: [EMAIL PROTECTED]; lars hofhansl <[EMAIL PROTECTED]>
> Sent: Sunday, August 4, 2013 4:27 PM
> Subject: Re: Heads up, HTablePool will be deprecated in 0.94, 0.95/0.96,
> and removed in 0.98
>
>
>
> bq. no funny business with unique Configurations
>
> Mind telling us what is funny about this part ?
>
>
> On Sat, Aug 3, 2013 at 10:41 PM, lars hofhansl <[EMAIL PROTECTED]> wrote:
>
> Correct. The HConnection is naturally shared between the HTables.
> >There is no longer any need to worry about this (no funny business with
> unique Configurations, in fact most of the code in HConnectionManager can
> be removed in trunk).
> >
> >It is also correct that the code now has to hold on the created
> HConnection, rather asking HConnectionManager for it.
> >
> >-- Lars
> >
> >
> >
> >________________________________
> > From: Nick Dimiduk <[EMAIL PROTECTED]>
> >To: [EMAIL PROTECTED]
> >Sent: Saturday, August 3, 2013 8:56 PM
> >
> >Subject: Re: Heads up, HTablePool will be deprecated in 0.94, 0.95/0.96,
> and removed in 0.98
> >
> >
> >On Sat, Aug 3, 2013 at 8:52 PM, Ted Yu <[EMAIL PROTECTED]> wrote:
> >
> >> Does this mean that user code wouldn't be able to depend