Hi all, I do not have a strong opinion on the topic yet, but I would like to share my thoughts on this.
In the solution proposing a wrapping AtlasExecutor around the Flink Executors, if we allow the user to use the CLI to submit jobs, then this means that the CLI code may have to change so that it injects the executor option to AtlasExecutor (transparently to the user), and then the AtlasExecutor should take what the user has actually set as pipeline executor and find the adequate executor. If this is not done transparently, then the user should do sth explicit to point Flink to Atlas and then to the correct executor, which implies that we should add user-facing stuff (like cli options) to Flink. For the solution of adding getPipeline() to the JobListener, I think that from a design perspective, it does not fit in the listener itself. The listener is a "passive" entity that is expected to listen to specific "events". Adding a getter does not fit there. Other options for the getPipeline() method are: 1) add it as a method to the JobClient 2) add it as an argument to the methods of the JobListener (along with the JobClient and the throwable) Alternative 1) would currently work because the JobClient is only instantiated by the executor. But in the future, we may (and probably will because of implications of FLIP-85) allow a JobClient to get "attached" to a running job. In this case, the getPipeline() will not have a pipeline to return. Alternative 2) will break existing code, which I am not sure how important this is as the JobListener is a new feature and I guess some but not many users. As a sidenote, if I am not mistaken, apart from Yarn, none of the above solutions would work in per-job mode for Kuberneter, Mesos or with web-submissions. These modes go through "special" execution environments that use them simply to extract the JobGraph which then they submit to the cluster. In this case, there is no executor involved. Are these cases important to you? Finally, another solution, although more drastic and more involved, could be to have a "JobListener" running on the jobMaster. This will collect the relevant info and send them to Atlas. But I am not sure how Atlas works and if it requires the data to be extracted on the client side. I am saying this because the JobMasters may be running anywhere in a cluster while the clients may run on designated machines which can have specific configurations, e.g. open ports to communicate with a specific Atlas server. Cheers, Kostas On Thu, Mar 12, 2020 at 3:19 PM Stephan Ewen <se...@apache.org> wrote: > > Hi Gyula! > > My main motivation was to try and avoid mixing an internal interface > (Pipeline) with public API. It looks like this is trying to go "public > stable", but doesn't really do it exactly because of mixing "pipeline" into > this. > You would need to cast "Pipeline" and work on internal classes in the > implementation. > > If we use an "internal API" or a "semi-stable SPI" class, it looks at a > first glance a bit cleaner and more maintainable (opening up less surface) > to make the PipelineExecutor a "stable SPI". > I have not checked out all the details, though. > > Best, > Stephan > > > On Thu, Mar 12, 2020 at 2:47 PM Gyula Fóra <gyula.f...@gmail.com> wrote: > > > Hi Stephan! > > > > Thanks for checking this out. I agree that wrapping the other > > PipelineExecutors with a delegating AtlasExecutor would be a good > > alternative approach to implement this but I actually feel that it suffers > > even more problems than exposing the Pipeline instance in the JobListener. > > > > The main idea with the Atlas integration would be to have the Atlas hook > > logic in the Atlas project where it would be maintained. This means that > > any approach we take has to rely on public APIs. The JobListener is already > > a public evolving API while the PipelineExecutor and the factory is purely > > internal. Even if we make it public it will still expose the Pipeline so we > > did not gain much on the public/internal API front. > > > > I also feel that since the Atlas hook logic should only observe the > > pipeline and collect information the JobListener interface seems an ideal > > match and the implementation can be pretty lightweight. From a purely > > implementation perspective adding an Executor would be more heavy as it has > > to properly delegate to an other executor making sure that we don't break > > anything. > > > > Don't take me wrong, I am not opposed to reworking the implementations we > > have as it's very simple at this point but I also want to make sure that we > > take the approach that is simple from a maintainability standpoint. Of > > course my argument rests on the assumption that the AtlasHook itself will > > live outside of the Flink project, thats another question. > > > > Cheers, > > Gyula > > > > On Thu, Mar 12, 2020 at 11:34 AM Stephan Ewen <se...@apache.org> wrote: > > > > > Hi all! > > > > > > In general, nice idea to support this integration with Atlas. > > > > > > I think we could make this a bit easier/lightweight with a small change. > > > One of the issues that is not super nice is that this starts exposing the > > > (currently empty) Pipeline interface in the public API. > > > The Pipeline is an SPI interface that would be good to hide in the API. > > > > > > Since 1.10, Flink has the notion of Executors, which take the pipeline > > and > > > execute them. Meaning each pipeline is passed on anyways. And executors > > are > > > already configurable in the Flink configuration. > > > So, instead of passing the pipeline both "down" (to the executor) and "to > > > the side" (JobListener), could we just have a wrapping "AtlasExecutor" > > that > > > takes the pipeline, does whatever it wants, and then passes it to the > > > proper executor? This would also have the advantage that it supports > > making > > > changes to the pipeline, if needed in the future. For example, if there > > is > > > ever the need to add additional configuration fields, set properties, add > > > "labels" or so, this could be easily done in the suggested approach. > > > > > > I tried to sketch this in the picture below, pardon my bad drawing. > > > > > > [image: Listener_Executor.png] > > > > > > > > > > > https://xjcrkw.bn.files.1drv.com/y4pWH57aEvLU5Ww4REC9XLi7nJMLGHq2smPSzaslU8ogywFDcMkP-_Rsl8B1njf4qphodim6bgnLTNFwNoEuwFdTuA2Xmf7CJ_8lTJjrKlFlDwrugVeBQzEhAY7n_5j2bumwDBf29jn_tZ1ueZxe2slhLkPC-9K6Dry_vpvRvZRY-CSnQXxj9jDf7P53Vz1K9Ez/Listener_Executor.png?psid=1 > > > > > > > > > Best, > > > Stephan > > > > > > > > > On Wed, Mar 11, 2020 at 11:41 AM Aljoscha Krettek <aljos...@apache.org> > > > wrote: > > > > > >> Thanks! I'm reading the document now and will get back to you. > > >> > > >> Best, > > >> Aljoscha > > >> > > > > >
