Hi Steve, I am not sure I fully understand what is broken here. It is not an incompatible change, right? Could you please explain what you think the process is. Would be best if you could share a link to a document describing it. I would be glad to follow up with tests and documentation that are needed.
As you can see I proposed multiple solutions to the problem in the jira. Seemed nobody was objecting, so I chose one and explained why. I believe we call it lazy consensus. Stay safe, --Konstantin On Sun, Dec 13, 2020 at 10:22 AM Chao Sun <sunc...@apache.org> wrote: > > This is an API where it'd be ok to have a no-op if not implemented, > correct? Or is there an requirement like Syncable that specific guarantees > are met？ > > Yes I think it's ok to leave it as no-op for other non-HDFS FS impls: it is > only used by HDFS standby reads so far. > > > > On Sun, Dec 13, 2020 at 4:58 AM Steve Loughran <ste...@cloudera.com> > wrote: > > > This isn't worth holding up the RC. We'd just add something to the > > release notes "use with caution". And if we can get what the API does > > defined in a way which works, it shouldn't need changing. > > > > (which reminds me, I do need to check that RC out, don't I?) > > > > On Sun, 13 Dec 2020 at 09:00, Xiaoqiao He <hexiaoq...@apache.org> wrote: > > > >> Thanks Steve very much for your discussion here. > >> > >> Leave some comments inline. Will focus on this thread to wait for the > >> final > >> conclusion to decide if we should prepare another release candidate of > >> 3.2.2. > >> Thanks Steve and Chao again for your warm discussions. > >> > >> On Sat, Dec 12, 2020 at 7:18 PM Steve Loughran > >> <ste...@cloudera.com.invalid> > >> wrote: > >> > >> > Maybe it's not in the release; it's certainly in the 3.2 branch. Will > >> check > >> > further. If it's in the release I was thinking of adding a warning in > >> the > >> > notes "unstable API"; stable if invoked from DFSClient > >> > >> On Fri, 11 Dec 2020 at 18:21, Chao Sun <sunc...@apache.org> wrote: > >> > > >> > > I'm just curious why this is included in the 3.2.2 release? > >> HDFS-15567 is > >> > > tagged with 3.2.3 and the corresponding HDFS-14272 on server side is > >> > tagged > >> > > with 3.3.0. > >> > > >> > >> Just checked that HDFS-15567 has been involved in Hadoop-3.2.2 RC4. > IIRC, > >> I > >> have cut branch-3.2.2 in early October, at that time branch-3.2.3 has > >> created but source code not freeze completely because several blocked > >> issues reported and code freeze has done about mid October. Some issues > >> which are tagged with 3.2.3 has also been involved in 3.2.2 during > >> that period, include HDFS-15567. I will check them later, and make sure > >> that we have mark the correct tags. > >> > >> > >> > > > >> > > > If it goes into FS/FC, what does it do for a viewfs with >1 > mounted > >> > HDFS? > >> > > Should it take path, msync(path) so that viewFS knows where to > forward > >> > it? > >> > > > >> > > The API shouldn't take any path - for viewFS I think it should call > >> this > >> > on > >> > > all the child file systems. It might also need to handle the case > >> where > >> > > some downstream clusters support this capability while others don't. > >> > > > >> > > >> > That's an extra bit of work for ViewFS then. It should probe for > >> capability > >> > and invoke as/when supported. > >> > > >> > > > >> > > > Options > >> > > 1. I roll HDFS-15567 back "please be follow process" > >> > > 2. Someone does a followup patch with specification and contract > test, > >> > view > >> > > FS. Add even more to the java > >> > > 3. We do as per HADOOP-16898 into an MSyncable interface and then > >> > > FileSystem & HDFS can implement. ViewFS and filterFS still need to > >> pass > >> > > through. > >> > > > >> > > I'm slightly in favor of the hasPathCapabilities approach and make > >> this a > >> > > mixin where FS impls can optionally support. Happy to hear what > others > >> > > think. > >> > > > >> > > >> > Mixins are great when FC and FS can both implement; makes it easier to > >> code > >> > against either. All the filtering/aggregating FS's will have to > >> implement > >> > it, which means that presence of the interface doesn't guarantee > >> support. > >> > > >> > This is an API where it'd be ok to have a no-op if not implemented, > >> > correct? Or is there an requirement like Syncable that specific > >> guarantees > >> > are met? > >> > > >> > > > >> > > Chao > >> > > > >> > > > >> > > On Fri, Dec 11, 2020 at 9:00 AM Steve Loughran > >> > <ste...@cloudera.com.invalid > >> > > > > >> > > wrote: > >> > > > >> > > > Silence from the HDFS team > >> > > > > >> > > > > >> > > > Hadoop 3.2.2 is in an RC; it has the new FS API call. I really > don't > >> > want > >> > > > to veto the release just because someone pulled up a method > without > >> > doing > >> > > > the due diligence. > >> > > >> > >> Thanks Steve started this discussion here. I agree to roll back > HDFS-15567 > >> if there are still some incompatible issues not resolved completely. And > >> release will not be the blocked things here, I would like to prepare > >> another RC if we would reach common agreement. To be honest, I think it > is > >> better to involve Shvachko here. > >> > >> > >> > > > Is anyone in the HDFS going to do that due diligence or should we > >> > include > >> > > > something in the release notes "msync()" must be considered > >> unstable. > >> > > > > >> > > > Then we can do a proper msync(). > >> > > > > >> > > > If it goes into FS/FC, what does it do for a viewfs with >1 > mounted > >> > HDFS? > >> > > > Should it take path, msync(path) so that viewFS knows where to > >> forward > >> > > it? > >> > > > > >> > > > Alternatively: go with an MSync interface which those few FS which > >> > > > implement it (hdfs) can do that, and the fact that it doesn't have > >> doc > >> > or > >> > > > tests won't be a blocker any more? > >> > > > > >> > > > -steve > >> > > > > >> > > > > >> > > > > >> > > > > >> > > > On Thu, 10 Dec 2020 at 12:41, Steve Loughran <ste...@cloudera.com > > > >> > > wrote: > >> > > > > >> > > > > > >> > > > > Gosh, has it really been only since february since I last asked > >> the > >> > > HDFS > >> > > > > dev list to stop adding anything to FileSystem/FileContext APIs > >> > without > >> > > > > > >> > > > > * mentioning this on the hadoop-common list. > >> > > > > * specifying what it does in filesystem.md > >> > > > > * with a contract test > >> > > > > * a new hasPathCapabilities probe. Throwing > >> > > UnsupportedOperationException > >> > > > > only lets people work out if it is unsupported through > invocation. > >> > > Being > >> > > > > able to probe for it is better. > >> > > > > * ViewFS support. > >> > > > > * And, for any new API, one which works well for high-latency > >> object > >> > > > > stores: returning Future<Something> and > >> > > Future<RemoteIterator<Something> > >> > > > > when > 1 result is returned > >> > > > > > >> > > > > This needs to hold even for pulling something up from HDFS. > >> Because > >> > if > >> > > > > another FS wants to implement it, they need to know what it > does, > >> and > >> > > > have > >> > > > > tests to verify this. I say this as someone who has tried to > >> document > >> > > > HDFS > >> > > > > rename() semantics and gave up. > >> > > > > > >> > > > > It's really frustrating that every time someone does an FS API > >> change > >> > > > like > >> > > > > this in the past (most recently HDFS-13616) I am the one who has > >> to > >> > > keep > >> > > > > sending the reminders out, and then having to try and clean up/. > >> > > > > > >> > > > > So what now? > >> > > > > > >> > > > > Options > >> > > > > 1. I roll HDFS-15567 back "please be follow process" > >> > > > > 2. Someone does a followup patch with specification and contract > >> > test, > >> > > > > view FS. Add even more to the java > >> > > > > 3. We do as per HADOOP-16898 into an MSyncable interface and > then > >> > > > > FileSystem & HDFS can implement. ViewFS and filterFS still need > to > >> > pass > >> > > > > through. > >> > > > > > >> > > > > *If nobody is going to volunteer for the specification/test > >> changes, > >> > > I'm > >> > > > > happy for the rollback. It'll remind people about process, * > >> > > > > > >> > > > > Pre-emptive Warning: No matter what we do for this patch, I will > >> roll > >> > > > back > >> > > > > the next change which adds a new API if it's not accompanied by > >> > > > > specification and tests. > >> > > > > > >> > > > > Unhappily yours, > >> > > > > > >> > > > > Steve > >> > > > > > >> > > > > >> > > > >> > > >> > > >
