[RESULT] VOTE: Merge HBASE-18070 "Enable memstore replication for meta replica" to master and then back to branch-2" (Was "HEAD-UP: Merging HBASE-18070 "Enable memstore replication for meta replica" to master and then back to branch-2")

[Stack <st...@duboce.net>]

With 5 binding and 1 non-binding votes in favor and no votes against, this
vote to merge passes.
Thanks to all who participated.
S

On Tue, Nov 17, 2020 at 8:43 AM Stack <st...@duboce.net> wrote:

> Please VOTE on whether to merge HBASE-18070 feature branch to master (and
> HBASE-18070.branch-2 to branch-2). The VOTE runs for 24 hours. The majority
> prevails (+ or -).
>
> Quoting the design lead-in:
>
> Read Replicas on the hbase:meta Table currently only does primitive read
> of the primary’s hfiles refreshing every (configurable) N seconds. This
> issue is about making it so we can do the Async WAL Replication
> <http://hbase.apache.org/book.html#_asnyc_wal_replication> ability,
> currently only available for user-space Tables, against the hbase:meta
> system Tables too; i.e. the primary replica pushes edits to its Replicas so
> they run much closer to the primaries’ state. If clients could be satisfied
> reading from Replicas, then we could have improved hbase:meta uptimes but
> also, we can distribute load off of the primary and alleviate hbase:meta
> Table (read) hotspotting.
>
> Each PR that comprises the feature branch has been reviewed before commit.
>
>  * For the design, see [2].
>  * For an amalgamated PR of the 5 or 6 reviewed PRs that comprise this
> feature, see [3].
>  * For a PE report that compared performance before and after, see
> HBASE-25127 (no regression).
>  * A report on ITBLL runs is pending to be attached to HBASE-18070 but
> runs so far show no regression with the feature enabled (ITBLL runs were
> done against a backport of this feature to branch-2 as the ITBLL state of
> master is currently an unknown).
>
> Testing continues mainly looking for further improvement and to better
> understand this feature in operation. Documentation is included. There are
> some follow-ons that have been identified but these can land later.
>
> Thanks and thanks to all who contributed to this feature; the reviewers
> and the testers in particular.
>
> S
>
> 1. http://hbase.apache.org/book.html#_asnyc_wal_replication
> 2.
> https://docs.google.com/document/d/1jJWVc-idHhhgL4KDRpjMsQJKCl_NRaCLGiH3Wqwd3O8/edit#
> This patch is currently missing HBASE-25280, a bug found in testing.
> 3. https://github.com/apache/hbase/pull/2643
>