On Mon, Jan 8, 2018 at 2:50 PM, 张铎(Duo Zhang) <palomino...@gmail.com> wrote:
> This 'new' feature only changes DDL part, not the core part of replication, > i.e, how to read wal entries and how to replicate it to the remote cluster, > etc. And also there is no pb message/storage layout change, you can think > of this as a big refactoring. Theoretically we even do not need to add new > UTs for this feature, i.e, no extra stability works. The only visible > change to users is that it may require more time on modifying peers in > shell. So in general I think it is less hurt to include it in the coming > release? > > And why I think it SHOULD be included in our 2.0 release is that, the > synchronous guarantee is really a good thing for our replication related > UTs. The correctness of the current Test***Replication usually depends on a > flakey condition - we will not do a log rolling between the modification on > zk and the actual loading of the modification on RS. And we have also done > a hard work to cleanup the lockings in ReplicationSourceManager and add a > fat comment to say why it should be synchronized in this way. In general, > the new code is much easier to read, test and debug, and also reduce the > possibility of flakeyness, which could help us a lot when we start to > stabilize our build. > > Thanks. > > You see it as a big bug fix Duo? I'm late to review. Will have a look after beta-1 goes out. This stuff looks great from outside, especially distributed procedure framework which we need all over the place. In general I have no problem w/ this in master and an hbase 2.1 (2.1 could be soon after 2.0). Its late for big stuff in 2.0.... but let me take a looksee sir. St.Ack > 2018-01-09 4:53 GMT+08:00 Apekshit Sharma <a...@cloudera.com>: > > > Same questions as Josh's. > > 1) We have RCs for beta1 now, which means only commits that can go in are > > bug fixes only. This change - although important, needed from long time > and > > well done (testing, summary, etc) - seems rather very large to get into > 2.0 > > now. Needs good justification why it has to be 2.1 instead of 2.0. > > > > -- Appy > > > > > > On Mon, Jan 8, 2018 at 8:34 AM, Josh Elser <els...@apache.org> wrote: > > > > > -0 From a general project planning point-of-view (not based on the > > > technical merit of the code) I am uncomfortable about pulling in a > brand > > > new feature after we've already made one beta RC. > > > > > > Duo -- can you expand on why this feature is so important that we > should > > > break our release plan? Are there problems that would make including > this > > > in a 2.1/3.0 unnecessarily difficult? Any kind of color you can provide > > on > > > "why does this need to go into 2.0?" would be helpful. > > > > > > > > > On 1/6/18 1:54 AM, Duo Zhang wrote: > > > > > >> https://issues.apache.org/jira/browse/HBASE-19397 > > >> > > >> We aim to move the peer modification framework from zk watcher to > > >> procedure > > >> v2 in this issue and the work is done now. > > >> > > >> Copy the release note here: > > >> > > >> Introduce 5 procedures to do peer modifications: > > >> > > >>> AddPeerProcedure > > >>> RemovePeerProcedure > > >>> UpdatePeerConfigProcedure > > >>> EnablePeerProcedure > > >>> DisablePeerProcedure > > >>> > > >>> The procedures are all executed with the following stage: > > >>> 1. Call pre CP hook, if an exception is thrown then give up > > >>> 2. Check whether the operation is valid, if not then give up > > >>> 3. Update peer storage. Notice that if we have entered this stage, > then > > >>> we > > >>> can not rollback any more. > > >>> 4. Schedule sub procedures to refresh the peer config on every RS. > > >>> 5. Do post cleanup if any. > > >>> 6. Call post CP hook. The exception thrown will be ignored since we > > have > > >>> already done the work. > > >>> > > >>> The procedure will hold an exclusive lock on the peer id, so now > there > > is > > >>> no concurrent modifications on a single peer. > > >>> > > >>> And now it is guaranteed that once the procedure is done, the peer > > >>> modification has already taken effect on all RSes. > > >>> > > >>> Abstracte a storage layer for replication peer/queue manangement, and > > >>> refactored the upper layer to remove zk related naming/code/comment. > > >>> > > >>> Add pre/postExecuteProcedures CP hooks to RegionServerObserver, and > add > > >>> permission check for executeProcedures method which requires the > caller > > >>> to > > >>> be system user or super user. > > >>> > > >>> On rolling upgrade: just do not do any replication peer modifications > > >>> during the rolling upgrading. There is no pb/layout changes on the > > >>> peer/queue storage on zk. > > >>> > > >>> > > >> And there are other benefits. > > >> First, we have introduced a general procedure framework to send tasks > to > > >> RS > > >> and report the report back to Master. It can be used to implement > other > > >> operations such as ACL change. > > >> Second, zk is used as a external storage now since we do not depend on > > zk > > >> watcher any more, it will be much easier to implement a 'table based' > > >> replication peer/queue storage. > > >> > > >> Please vote: > > >> [+1] Agree > > >> [-1] Disagree > > >> [0] Neutral > > >> > > >> Thanks. > > >> > > >> > > > > > > -- > > > > -- Appy > > >
