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 > >> > Meaning he / she should be prepared to endorse metrics2 framework. > >> > > >> > >> Hadoop deprecating metrics in favor of metrics2 is independent of us > >> deprecating HBase metrics classes. TimeStampingFileContext is one > >> MetricsContext implementation in HBase that would need to be > >> deprecated and could be used or possibly extended by current users. > >> > >> Ultimately it's up to Lars H as RM for 0.94 to decide what he wants to > >> include. It just feels to me like we're rushing to deprecate metrics > >> in 0.94 so that it can be removed in 0.96, instead of what seems to me > >> like the more standard path of deprecating metrics in 0.96, while also > >> including new metrics2 implementations, which would give users a > >> smoother path to actually switch over. I'm just not sure I understand > >> the motivation for deprecating in 0.94 instead of 0.96. > >> >
