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https://issues.apache.org/jira/browse/HBASE-6411?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13421659#comment-13421659
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Elliott Clark commented on HBASE-6411:
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bq.There's no access to the registry from outside the BaseMetricsSourceImpl
class, so I don't see how extracting changes things. In the MetricsRegistry
impl that I added you can see that concurrent maps are used to hold metrics.
Didn't think that tags will be created a lot, but rather in initialization
methods once, so haven't changed to using concurrent map for it.
The only usage before was through a guaranteed singleton that was only used on
a single thread at a time (The master rpc thread or the replication thread).
Once there's the possibility that a registry can be shared other places we need
to guard against concurrent access. I would vote using concurrent hash maps.
That's usually my preferred way beacuse it's faster if there is a lot of
contention.
bq.I agree, I haven't added it. It is from hadoop's code, as Ted Yu mentioned.
I.e. I have same thoughts about doing exactly this:
Awesome. we're on the same page then. Too bad it's already in shipped hadoop
code. Seems like a design flaw on their part. Oh well.
bq. That is why I suggested we replace this class with the registry in the
first place.
When I started part of my purpose was to do the clean up so that the
interfaces, used by classes in hbase-server, are not in any way tied to
metrics2. I want to modularize things and make most of hbase's use of hadoop
actually pluggable.
> Move Master Metrics to metrics 2
> --------------------------------
>
> Key: HBASE-6411
> URL: https://issues.apache.org/jira/browse/HBASE-6411
> Project: HBase
> Issue Type: Sub-task
> Reporter: Elliott Clark
> Assignee: Elliott Clark
> Attachments: HBASE-6411-0.patch, HBASE-6411-1.patch,
> HBASE-6411-2.patch, HBASE-6411_concept.patch
>
>
> Move Master Metrics to metrics 2
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