If the goal is to keep job creation and job submission separate and we agree that there should be more flexibility for the job construction, then JobGraph and friends should be stable API that the user can depend on. If that's the case, the path Chesnay pointed to may become viable.
There was discussion in the past that JobGraph cannot be relied on WRT backward compatibility and I would expect that at some point we want to move to a representation that allows for cross version compatibility. Beam is an example how this could be accomplished (with its pipeline proto). So if the Beam job server was able to produce the JobGraph, is there agreement that we should provide a mechanism that allows the program entry point to return the JobGraph directly (without using the ExecutionEnvironment to build it)? On Mon, Aug 5, 2019 at 2:10 AM Zili Chen <wander4...@gmail.com> wrote: > Hi Thomas, > > If REST handler calls main(), the behavior inside main() is > unpredictable. > > Now the jar run handler extract the job graph and submit > it with the job id configured in REST request. If REST > handler calls main() we can hardly even know how much > jobs are executed. > > A new environment, as you said, > ExtractJobGraphAndSubmitToDispatcherEnvironment can be > added to satisfy your requirement. However, it is a bit > out of Flink scope. It might be better to write your own > REST handler. > > WebMonitorExtension is for extending REST handlers but > it seems also unable to customize... > > Best, > tison. > > > Thomas Weise <t...@apache.org> 于2019年8月3日周六 上午4:09写道： > > > Thanks for looking into this. > > > > I see the "Jar run handler" as function that takes few parameters and > > returns a job ID. I think it would be nice if the handler doesn't hard > code > > the function. Perhaps this could be accomplished by pushing the code into > > something like "ExtractJobGraphAndSubmitToDispatcherEnvironment" that the > > main method could also bypass if it has an alternative way to provide the > > jobId via a context variable? > > > > Zili: I looked at the client API proposal and left a few comments. I > think > > it is important to improve programmatic job submission. But it also seems > > orthogonal to how the jar run handler operates (i.e. these issues could > be > > addressed independently). > > > > Chesnay: You are right that the Beam job sever could be hacked to extract > > job graph and other ingredients. This isn't desirable though because > these > > Flink internals should not be exposed downstream. But even if we went > down > > that route we would still need a way to let the jar run handler know to > > just return the ID of an already submitted job vs. trying to submit one > > from OptimizerPlanEnvironment. > > > > The intended sequence would be: > > > > REST client provides a launcher jar > > REST client "runs jar" > > REST handler calls main() > > main launches Beam job server, runs Beam pipeline construction code > against > > that job server > > job server uses RemoteEnvironment to submit real job > > main "returns job id" > > REST handler returns job id > > > > Thomas > > > > > > On Wed, Jul 31, 2019 at 4:33 AM Zili Chen <wander4...@gmail.com> wrote: > > > > > By the way, currently Dispatcher implements RestfulGateway > > > and delegate resource request to ResourceManager. If we can, > > > semantically, let WebMonitor implement RestfulGateway, > > > and delegate job request to Dispatcher, resource request to > > > ResourceManager, it seems reasonable that when WebMonitor > > > receives a JarRun request, it spawns a process and run > > > the main method of the main class of that jar. > > > > > > Best, > > > tison. > > > > > > > > > Zili Chen <wander4...@gmail.com> 于2019年7月31日周三 下午7:10写道： > > > > > >> I don't think the `Program` interface could solve the problem. > > >> > > >> The launcher launches the job server which creates the job graph, > > >> submits it and keeps monitoring. Even if user program implement > > >> `Program` Flink still extracts the JobGraph from `getPlan` and > > >> submits it, instead of really execute codes in main method of > > >> user program, so that the launcher is not started. > > >> > > >> @Thomas, > > >> > > >> Here is an ongoing discussion on client refactoring[1] as Till > > >> mentioned. However, I'm afraid that with current jar run semantic, > > >> i.e., extract the job graph and submit it to the Dispatcher, it cannot > > >> fits your requirement. The problem is that REST API directly > > >> communicates with Dispatcher and thus it's strange to tell the > > >> Dispatcher "just run a program in a process". > > >> > > >> As you mentioned in the document, with CLI in session mode the > > >> whole program would be executed sequentially. I'll appreciate it > > >> if you can participant the thread on client refactor[1]. In the > > >> design document[2], we propose to provide rich interfaces for > > >> downstream projects integration. You can customize your CLI for > > >> executing your program arbitrarily. Any requirement or advise > > >> would be help. > > >> > > >> Best, > > >> tison. > > >> > > >> [1] > > >> > > > https://lists.apache.org/thread.html/ce99cba4a10b9dc40eb729d39910f315ae41d80ec74f09a356c73938@%3Cdev.flink.apache.org%3E > > >> [2] > > >> > > > https://docs.google.com/document/d/1UWJE7eYWiMuZewBKS0YmdVO2LUTqXPd6-pbOCof9ddY/edit > > >> > > >> > > >> > > >> > > >> Till Rohrmann <trohrm...@apache.org> 于2019年7月31日周三 下午4:50写道： > > >> > > >>> Are you looking for something similar to the `Program` interface? > This > > >>> interface, even though it is a bit outdated and might get removed in > > the > > >>> future, offers a `getPlan` method which is called in order to > generate > > >>> the > > >>> `JobGraph`. In the client refactoring discussion thread it is > currently > > >>> being discussed what to do with this interface. > > >>> > > >>> Cheers, > > >>> Till > > >>> > > >>> On Wed, Jul 31, 2019 at 10:41 AM Chesnay Schepler < > ches...@apache.org> > > >>> wrote: > > >>> > > >>> > Couldn't the beam job server use the same work-around we're using > in > > >>> the > > >>> > JarRunHandler to get access to the JobGraph? > > >>> > > > >>> > On 26/07/2019 17:38, Thomas Weise wrote: > > >>> > > Hi Till, > > >>> > > > > >>> > > Thanks for taking a look! > > >>> > > > > >>> > > The Beam job server does not currently have the ability to just > > >>> output > > >>> > the > > >>> > > job graph (and related artifacts) that could then be used with > the > > >>> > > JobSubmitHandler. It is itself using StreamExecutionEnvironment, > > >>> which in > > >>> > > turn will lead to a REST API submission. > > >>> > > > > >>> > > Here I'm looking at what happens before the Beam job server gets > > >>> > involved: > > >>> > > the interaction of the k8s operator with the Flink deployment. > The > > >>> jar > > >>> > run > > >>> > > endpoint (ignoring the current handler implementation) is generic > > and > > >>> > > pretty much exactly matches what we would need for a uniform > entry > > >>> point. > > >>> > > It's just that in the Beam case the jar file would itself be a > > >>> "launcher" > > >>> > > that doesn't provide the job graph itself, but the dependencies > and > > >>> > > mechanism to invoke the actual client. > > >>> > > > > >>> > > I could accomplish what I'm looking for by creating a separate > REST > > >>> > > endpoint that looks almost the same. But I would prefer to reuse > > the > > >>> > Flink > > >>> > > REST API interaction that is already implemented for the Flink > Java > > >>> jobs > > >>> > to > > >>> > > reduce the complexity of the deployment. > > >>> > > > > >>> > > Thomas > > >>> > > > > >>> > > > > >>> > > > > >>> > > > > >>> > > On Fri, Jul 26, 2019 at 2:29 AM Till Rohrmann < > > trohrm...@apache.org> > > >>> > wrote: > > >>> > > > > >>> > >> Hi Thomas, > > >>> > >> > > >>> > >> quick question: Why do you wanna use the JarRunHandler? If > another > > >>> > process > > >>> > >> is building the JobGraph, then one could use the > JobSubmitHandler > > >>> which > > >>> > >> expects a JobGraph and then starts executing it. > > >>> > >> > > >>> > >> Cheers, > > >>> > >> Till > > >>> > >> > > >>> > >> On Thu, Jul 25, 2019 at 7:45 PM Thomas Weise <t...@apache.org> > > >>> wrote: > > >>> > >> > > >>> > >>> Hi, > > >>> > >>> > > >>> > >>> While considering different options to launch Beam jobs through > > the > > >>> > Flink > > >>> > >>> REST API, I noticed that the implementation of JarRunHandler > > places > > >>> > >> quite a > > >>> > >>> few restrictions on how the entry point shall construct a Flink > > >>> job, by > > >>> > >>> extracting and manipulating the job graph. > > >>> > >>> > > >>> > >>> That's normally not a problem for Flink Java programs, but in > the > > >>> > >> scenario > > >>> > >>> I'm looking at, the job graph would be constructed by a > different > > >>> > process > > >>> > >>> and isn't available to the REST handler. Instead, I would like > to > > >>> be > > >>> > able > > >>> > >>> to just respond with the job ID of the already launched job. > > >>> > >>> > > >>> > >>> For context, please see: > > >>> > >>> > > >>> > >>> > > >>> > >>> > > >>> > >> > > >>> > > > >>> > > > https://docs.google.com/document/d/1z3LNrRtr8kkiFHonZ5JJM_L4NWNBBNcqRc_yAf6G0VI/edit#heading=h.fh2f571kms4d > > >>> > >>> The current JarRunHandler code is here: > > >>> > >>> > > >>> > >>> > > >>> > >>> > > >>> > >> > > >>> > > > >>> > > > https://github.com/apache/flink/blob/f3c5dd960ff81a022ece2391ed3aee86080a352a/flink-runtime-web/src/main/java/org/apache/flink/runtime/webmonitor/handlers/JarRunHandler.java#L82 > > >>> > >>> It would be nice if there was an option to delegate the > > >>> responsibility > > >>> > >> for > > >>> > >>> job submission to the user code / entry point. That would be > > >>> useful for > > >>> > >>> Beam and other frameworks built on top of Flink that > dynamically > > >>> > create a > > >>> > >>> job graph from a different representation. > > >>> > >>> > > >>> > >>> Possible ways to get there: > > >>> > >>> > > >>> > >>> * an interface that the main class can be implement end when > > >>> present, > > >>> > the > > >>> > >>> jar run handler calls instead of main. > > >>> > >>> > > >>> > >>> * an annotated method > > >>> > >>> > > >>> > >>> Either way query parameters like savepoint path and parallelism > > >>> would > > >>> > be > > >>> > >>> forwarded to the user code and the result would be the ID of > the > > >>> > launched > > >>> > >>> job. > > >>> > >>> > > >>> > >>> Thougths? > > >>> > >>> > > >>> > >>> Thanks, > > >>> > >>> Thomas > > >>> > >>> > > >>> > > > >>> > > > >>> > > >> > > >
