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From Jesse Daniels <jessedanie...@gmail.com>
Subject Re: Coprocessors - Only One User Priority Coprocessor Permitted?
Date Fri, 11 Mar 2011 04:25:25 GMT
Done: https://issues.apache.org/jira/browse/HBASE-3624.

On Thu, Mar 10, 2011 at 5:12 PM, Gary Helmling <ghelmling@gmail.com> wrote:

> Hi Jesse,
> Yes, the intent is definitely to allow chaining of multiple user
> coprocessors for the same table.  If EnvironmentPriorityComparator is
> blocking that, that is definitely a bug and we should get it fixed.
> Would you mind opening a JIRA for the issue?
> Thanks,
> Gary
> On Thu, Mar 10, 2011 at 4:33 PM, Jesse Daniels <jessedaniels1@gmail.com>wrote:
>> I’m experimenting with the coprocessor functionality in trunk,
>> specifically
>> region observers. The documentation talks about the ability to chain
>> coprocessors such that they are called one after another. I noticed in the
>> source (CoprocessorHost.java) that coprocessors are added to HBase using a
>> TreeSet that is initialized with an EnvironmentPriorityComparator. I’m
>> discovering that the net effect of this is that only one “User” priority
>> coprocessor can be loaded at a time. This appears to be due to how the
>> TreeSet uses the EnvironmentPriorityComparator to determine whether there
>> are duplicate entries – if the coprocessors have the same priority (e.g.,
>> User), they are considered the same and won’t be added to the Set. I'm
>> guessing this isn't the desired behavior? I originally assumed that you
>> could have multiple user coprocessors per table and therefore the
>> comparator
>> should be by class name or something more unique.
>> Thanks for your insight.

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