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HBase, mail # dev - deprecating (old) metrics in favor of metrics2 framework


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Re: deprecating (old) metrics in favor of metrics2 framework
Elliott Clark 2012-07-10, 22:33
https://issues.apache.org/jira/browse/HADOOP-7734

As far as I can tell this basically sinks all Metrics2 usage in HBase.

On Tue, Jul 10, 2012 at 3:24 PM, Alex Baranau <[EMAIL PROTECTED]>wrote:

> > If there's considerable pain or overhead in having both
> > implementations live in parallel, maybe it's worth doing a straight
> > switch over in 0.96.
>
> As far as I can tell, they can live together easily. This should not be a
> big issue. E.g. it should be much smaller issue than the fact that code
> implemented on top of metrics2 will not compile against 1.0+, 2.0+ and 3.0+
> hadoop at the same time because class names, etc. changed between 1.0 and
> 2.0. But that's a separate story, will look at it tomorrow (Ted pointed me
> to smth to look at).
>
> Alex Baranau
>
> On Tue, Jul 10, 2012 at 5:03 PM, Ted Yu <[EMAIL PROTECTED]> wrote:
>
> > Points taken.
> >
> > Thanks for the education of metrics framework history.
> >
> > On Tue, Jul 10, 2012 at 1:55 PM, Gary Helmling <[EMAIL PROTECTED]>
> > wrote:
> >
> > > I agree that having a new metrics2 implementation in 0.96 would be
> > > great to see and seems like a natural fit.  I'm 100% for that.  But I
> > > do think that having metrics2 and (deprecated) metrics v1 in the same
> > > release would be very helpful to users making the transition.  So to
> > > me it seems more natural for 0.96 to be that release with both
> > > implementations, since that's where it seems like the metrics2
> > > implementation will land.
> > >
> > > Otherwise it seems like we risk introducing the same disruptions that
> > > Hadoop did when metrics2 initially replaced the metrics v1
> > > implementation, instead of living along side.  This did cause us as a
> > > project some trouble until metrics v1 was added back in.  So it would
> > > be unfortunate to repeat the same mistake ourselves.
> > >
> > > If there's considerable pain or overhead in having both
> > > implementations live in parallel, maybe it's worth doing a straight
> > > switch over in 0.96.  I haven't looked at the differences enough
> > > myself to know.  But otherwise it seems like an easier migration path
> > > to deprecate v1 in 0.96 and remove the release after.
> > >
> > >
> > > On Tue, Jul 10, 2012 at 1:35 PM, Ted Yu <[EMAIL PROTECTED]> wrote:
> > > > Gary:
> > > > Your comment makes sense.
> > > >
> > > > Part of this poll originates from the fact that 0.96 is our
> singularity
> > > > release. RPC, coprocessor, etc have undergone considerable changes.
> > > > Users migrating to 0.96 would have to deal with a lot of updates in
> > their
> > > > codebase.
> > > >
> > > > It seems to me that doing all upgrades in one shot is almost the same
> > as
> > > > upgrading components other than metrics framework.
> > > >
> > > > Cheers
> > > >
> > > > On Tue, Jul 10, 2012 at 1:29 PM, Gary Helmling <[EMAIL PROTECTED]>
> > > wrote:
> > > >
> > > >> >
> > > >> > Whether we support 2 (actually more than 2) metrics frameworks in
> > 0.96
> > > >> can
> > > >> > be debated in the next 2 months.
> > > >> >
> > > >>
> > > >> I'm not sure I agree that deprecating without having something in
> > > >> place for users to move to makes sense.
> > > >>
> > > >> > As Todd mentioned in the thread 'HBase 0.94.1', we will try our
> best
> > > to
> > > >> > keep JMX interface the same across 0.94 and 0.96. Does this
> somehow
> > > >> reduce
> > > >> > the concern you raised ?
> > > >> >
> > > >>
> > > >> I think that maintaining consistency with the existing JMX naming
> > > >> conventions (to the extent possible) is important for operational
> > > >> concerns, but it's independent of the MetricsContext question and
> the
> > > >> question of whether other metrics classes of our own need a proper
> > > >> deprecation cycle.
> > > >>
> > > >> > As for using MetricsContext, I assume the user also uses hadoop in
> > > his /
> > > >> > her deployment. Then he / she should be aware of the deprecation
> of
> > > >> > metrics.* classes in both hadoop 1.0 and 2.0