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From Vladimir Rodionov <vrodio...@carrieriq.com>
Subject Couple notes and questions on RegionObserver's
Date Thu, 25 Jul 2013 03:31:43 GMT
On design:

Why is the instance per region if we specify region in every call to RegionObserver anyway(
through RegionCoprocessorEnvironment)? The coprocessor instance is attached to every table
region and
receives the very same region as a parameter of every call except start/stop?

I want one coprocessor instance per RegionServer->Table or I want one Instance per RegionServer.
Its not feasible currently?

On implementation:
1.  stop() is always called after postClose - this one I tested
2. start() is always called before preOpen() ?

OK. this is annoying. The contract of start/stop becomes unclear. I though that we start should
be called on coprocessor load and
stop - on RS shutdown.

3. abortRequested parameter is always false. Yes, its for testing but how can I distinguish
disabling table and RS shutdown?

4. How can I intercept (or get notified on) RS shutdown request from inside a coprocessor?

and the last one:

5. I have one table and one region - hence one coprocessor instance. When I disable table
I observe the following sequence of calls:


preClose is called three times in row. Is it feature or a bug?

This was tested with MiniHBaseCluster. Hbase

Best regards,
Vladimir Rodionov
Principal Platform Engineer
Carrier IQ, www.carrieriq.com
e-mail: vrodionov@carrieriq.com

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