Hi Jun, I think this KIP helps to gain insight into how many clients have been upgraded *before* the we decide to upgrade the message format. In other words, users will know if they will pay down conversion cost before message format upgrade. It is about making an informed decision. To be conservative, users can wait until all clients have been upgraded before changing message format, which will guarantee zero down conversion cost.
While for the KIP you mentioned, users will only know the cost of down conversion after format upgrade, which may be too late. Thanks, Allen On Thu, Mar 29, 2018 at 6:16 PM, Jun Rao <j...@confluent.io> wrote: > Hi, Allen, > > Thanks for the KIP. > > It seems the main motivation of the KIP is to estimate the ratio of the > clients doing down conversion. I am wondering if we can do that by relying > on the metrics we added in 1.0.0 ( > https://cwiki.apache.org/confluence/display/KAFKA/KIP- > 188+-+Add+new+metrics+to+support+health+checks#KIP-188- > Addnewmetricstosupporthealthchecks-Messageconversionrateandtime). > This metric reports the message rate of down conversion. By comparing this > to the message rate of all consumers, you can roughly estimate the ratio of > consumers still needing down conversion. Does that cover the main thing > that you want from this KIP? > > Jun > > > > On Wed, Mar 28, 2018 at 9:55 AM, Allen Wang <allenxw...@gmail.com> wrote: > > > Hi All, > > > > I would like to start voting for KIP-272: Add API version tag to > broker's > > RequestsPerSec metric. > > > > https://cwiki.apache.org/confluence/display/KAFKA/KIP- > > 272%3A+Add+API+version+tag+to+broker%27s+RequestsPerSec+metric > > > > Thanks, > > Allen > > >
