I took a look. Its great. Our replication is in bad need of loving. The patch does a refactor/revamp/fix of an internal facility putting our peer management up on a Pv2 basis. It also moves forward the long-rumored distributed procedure project.
Its a big change though. Would have been great to have it make 2.0.0 but it didn't. I'd be up for it in a minor release rather than wait on 3.0.0 given we allow ourselves some leeway adding facility on minors and that it is at core a solidifying fix. Needs to be doc'd and tested, verified on a deploy beyond unit test. I could help test. Is it proven compatible with existing replication deploys? Who's the 3.0.0 RM? When is it going to roll? Having this in place is best argument if folks propose back-ports. Without, we are doomed to repeat the 2.0.0 experience. Thanks, St.Ack On Tue, Mar 13, 2018 at 3:44 AM, 张铎(Duo Zhang) <palomino...@gmail.com> wrote: > I've already merged it to branch-2... > > And for the procedure based replication peer modification, the feature has > been finished, at least no critical TODOs. I will not say it has no bugs > but I do not think it will block the 2.1 or 3.0 release too much. > > And please trust my judgement, I'm not a man who only want to show off. For > example I just reverted the serial replication feature from branch-2 before > we release beta2 and tried to redo it on master because we found some > critical problems. And since the basic idea has not been changed so we > decided to do it on master because it will not spend too much time to > finish. And for HBASE-19064 it is a big feature so we decided to do it on a > feature branch. We will select the branches which we want to merge back at > the time we finish the feature. > > For the CP cleanup, I think the problem is we started too late, and in the > past we made mistakes and let the related projects inject too much into the > internal of HBase. And for B&R, it is something like the serial replication > feature. For serial replication feature is that we tested it and found some > critical problems, and for B&R it was not well tested(IIRC) so we were > afraid of there will be critical problems. And for the AMv2, I think the > problem is premature optimization. We even implemented our own AvlTree, and > also a very complicated scheduler which always makes us dead lock... > > These are all very good cases for software engineering in the real world... > Should be avoided in the future... That's also my duty... > > Thanks. > > 2018-03-13 17:50 GMT+08:00 Apekshit Sharma <a...@cloudera.com>: > > > I thought the problem with releasing 2.0 was that there were too many > open > > features dragging along not coming to finish- AMv2 (biggest one), CP > > cleanup, B&R, etc. > > If it was not the case, it wouldn't have been 1 year between first alpha > > and GA, rather just few months. > > > > That said, i don't mind new but hardened features which are already ready > > to ship (implementation only or not) going in minor version, but that's > my > > personal opinion. But going too aggressive on that can indeed lead to the > > trap Josh mentioned above. > > > > For this particular change, my +1 was based on following aspects: > > - it's internal > > - moving ops procv2 framework (gives failure recovery, locking, etc) > > - Duo's reasoning - "....the synchronous guarantee is really a good thing > > for our replication related UTs..." and "For the replication peer > tracking, > > it is the same problem. It is hard to do fencing with zk watcher since it > > is asynchronous, so the UTs are always kind of flakey in theoretical." > > > > That said, it's pending review. > > @Duo: As you know it's not possible to spend cycles on it right now - > > pending 2.0GA - can you please hold it off for few weeks (ideally, until > GA > > + 2-3 weeks) which will give community (whoever interested, at least > > me..smile) a decent change to review it. > > Thanks > > > > -- Appy > > > > > > On Tue, Mar 13, 2018 at 1:02 AM, Josh Elser <els...@apache.org> wrote: > > > > > (Sorry for something other than just a vote) > > > > > > I worry seeing a "big" feature branch merge as us falling back into the > > > 1.x trap. Starting to backport features into 2.x will keep us delaying > > 3.0 > > > as we have less and less incentive to push to release 3.0 in a timely > > > manner. > > > > > > That said, I also don't want my worries to bar a feature which appears > to > > > be related to implementation only (based on one high-level read of the > > > changes). Perhaps we need to re-think what is allowable for a Y release > > in > > > x.y.z... > > > > > > +1 for master (which already happened, maybe?) > > > +0 for branch-2 (simply because I haven't looked closely enough at > > > changes, can read through and try to change to +1 if you need the > votes) > > > > > > > > > On 3/9/18 2:41 AM, 张铎(Duo Zhang) wrote: > > > > > >> Since branch-2.0 has been cut and branch-2 is now 2.1.0-SNAPSHOT, will > > >> merge branch HBASE-19397-branch-2 back to branch-2. > > >> > > >> 2018-01-10 9:20 GMT+08:00 张铎(Duo Zhang) <palomino...@gmail.com>: > > >> > > >> If branch-2.0 will be out soon then let's target this to 2.1. No > > problem. > > >>> > > >>> Thanks. > > >>> > > >>> 2018-01-10 1:28 GMT+08:00 Stack <st...@duboce.net>: > > >>> > > >>> On Mon, Jan 8, 2018 at 8:19 PM, 张铎(Duo Zhang) <palomino...@gmail.com > > > > >>>> wrote: > > >>>> > > >>>> OK, let me merge it master first. And then create a > > HBASE-19397-branch-2 > > >>>>> which will keep rebasing with the newest branch-2 to see if it is > > >>>>> stable > > >>>>> enough. Since we can define this as a bug fix/refactoring rather > > than a > > >>>>> > > >>>> big > > >>>> > > >>>>> new feature, it is OK to integrate it at any time. If we think it > is > > >>>>> > > >>>> stable > > >>>> > > >>>>> enough before cutting branch-2.0 then we can include it in the > 2.0.0 > > >>>>> release, else let's include it in 2.1(Maybe we can backport it to > 2.0 > > >>>>> later?). > > >>>>> > > >>>>> > > >>>>> > > >>>> I need to cut the Appy-suggested branch-2.0. Shout if > > >>>> HBASE-19397-branch-2 > > >>>> gets to be too much work and I'll do it sooner rather than later. > Or, > > if > > >>>> easier on you, just say and I'll make the branch-2.0 now so you can > > just > > >>>> commit to branch-2 (branch-2.0 will become hbase2.0, branch-2 will > > >>>> become > > >>>> hbase2.1...). > > >>>> > > >>>> St.Ack > > >>>> > > >>>> > > >>>> > > >>>> > > >>>> Thanks all here. > > >>>>> > > >>>>> 2018-01-09 12:06 GMT+08:00 ashish singhi <ashish.sin...@huawei.com > >: > > >>>>> > > >>>>> +1 to merge on master and 2.1. > > >>>>>> Great work. > > >>>>>> > > >>>>>> Thanks, > > >>>>>> Ashish > > >>>>>> > > >>>>>> -----Original Message----- > > >>>>>> From: 张铎(Duo Zhang) [mailto:palomino...@gmail.com] > > >>>>>> Sent: Tuesday, January 09, 2018 6:53 AM > > >>>>>> To: dev@hbase.apache.org > > >>>>>> Subject: Re: [VOTE] Merge branch HBASE-19397 back to master and > > >>>>>> > > >>>>> branch-2. > > >>>> > > >>>>> > > >>>>>> Anyway, if no objections on merging this into master, let's do it? > > So > > >>>>>> > > >>>>> that > > >>>>> > > >>>>>> we can start working on the follow-on features, such as table > based > > >>>>>> replication storage, and synchronous replication, etc. > > >>>>>> > > >>>>>> Thanks. > > >>>>>> > > >>>>>> 2018-01-09 7:19 GMT+08:00 Stack <st...@duboce.net>: > > >>>>>> > > >>>>>> 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? > > >>>>>>> > > >>>>>>> Kind of. Just like the AM v1, we can do lots of fix to make it > more > > >>>>>> stable, but we know that we can not fix all the problems since we > > >>>>>> > > >>>>> store > > >>>> > > >>>>> state in several places and it is a 'mission impossible' to make > all > > >>>>>> > > >>>>> the > > >>>> > > >>>>> states stay in sync under every situation... So we introduce AM v2. > > >>>>>> For the replication peer tracking, it is the same problem. It is > > hard > > >>>>>> > > >>>>> to > > >>>> > > >>>>> do fencing with zk watcher since it is asynchronous, so the UTs are > > >>>>>> > > >>>>> always > > >>>>> > > >>>>>> kind of flakey in theoretical. And we depend on replication > heavily > > at > > >>>>>> Xiaomi, it is always a pain for us. > > >>>>>> > > >>>>>> > > >>>>>>> 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. > > >>>>>>> > > >>>>>>> Thanks sir. All the concerns here about whether we should merge > > this > > >>>>>> > > >>>>> into > > >>>> > > >>>>> 2.0 are reasonable, I know. Although I really want this in 2.0 > > >>>>>> > > >>>>> because I > > >>>> > > >>>>> believe it will help a lot for stabilizing, I'm OK with merge it > to > > >>>>>> > > >>>>> 2.1 > > >>>> > > >>>>> only if you guys all think so. > > >>>>>> > > >>>>>> > > >>>>>>> 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 > > >>>>>>>>> > > >>>>>>>>> > > >>>>>>>> > > >>>>>>> > > >>>>>> > > >>>>> > > >>>> > > >>> > > >>> > > >> > > > > > > -- > > > > -- Appy > > >
