Had a short sync with Tom. I am going to postpone this for now since this case is very unlikely - I have seen this twice for the last 5 years. We'll go for a vote when we happen to see this more, and make a decision based on the feedback in the vote thread.
2020년 5월 11일 (월) 오후 11:08, Hyukjin Kwon <gurwls...@gmail.com>님이 작성: > The guide is our official guide, see "Code Style Guide" in > http://spark.apache.org/contributing.html. > As I said this is a general guidance, instead of a hard strict policy. I > don't target to change existing APIs either. > I would like to not start the vote when I see the clear objection to > address, Tom. I would like to address it. > > > So as I've already stated and it looks like 2 others have issues with > number 4 as written as well, I'm against you posting this as is. I do not > think we should recommend 4 for public user facing Scala API > > The main argument from you looks Scala/Java friendly (and Java users are > smaller than Scala). > The first argument is not quite correct because using Java is in the > official Scala guide. As I mentioned, it is not awkward if we use `Array` > for both Scala and Java as an example. > Such cases are very few, and seems it's best to stick to what Spark has > been done to support a single API for both Scala and Java. > > > 2020년 5월 11일 (월) 오후 10:45, Tom Graves <tgraves...@yahoo.com>님이 작성: > >> So as I've already stated and it looks like 2 others have issues with >> number 4 as written as well, I'm against you posting this as is. I do not >> think we should recommend 4 for public user facing Scala API. >> >> Also note the page you linked is a Databricks page, while I know we >> reference it as a style guide, I do not believe we should be putting API >> policy on that page, it should live on an Apache Spark page. >> >> I think if you want to implement an API policy like this it should go >> through an official vote thread, not just a discuss thread where we have >> not had a lot of feedback on it. >> >> Tom >> >> >> >> On Monday, May 11, 2020, 06:44:31 AM CDT, Hyukjin Kwon < >> gurwls...@gmail.com> wrote: >> >> >> I will wait a couple of more days and if there's no objection I hear, I >> will document this at >> https://github.com/databricks/scala-style-guide#java-interoperability. >> >> 2020년 5월 7일 (목) 오후 9:18, Hyukjin Kwon <gurwls...@gmail.com>님이 작성: >> >> Hi all, I would like to proceed this. Are there more thoughts on this? If >> not, I would like to go ahead with the proposal here. >> >> 2020년 4월 30일 (목) 오후 10:54, Hyukjin Kwon <gurwls...@gmail.com>님이 작성: >> >> Nothing is urgent. I just don't want to leave it undecided and just keep >> adding Java APIs inconsistently as it's currently happening. >> >> We should have a set of coherent APIs. It's very difficult to change APIs >> once they are out in releases. I guess I have seen people here agree with >> having a general guidance for the same reason at least - please let me know >> if I'm taking it wrong. >> >> I don't think we should assume Java programmers know how Scala works with >> Java types. Less assumtion might be better. >> >> I feel like we have things on the table to consider at this moment and >> not much point of waiting indefinitely. >> >> But sure maybe I am wrong. We can wait for more feedback for a couple of >> days. >> >> >> On Thu, 30 Apr 2020, 18:59 ZHANG Wei, <wezh...@outlook.com> wrote: >> >> I feel a little pushed... :-) I still don't get the point of why it's >> urgent to make the decision now. AFAIK, it's a common practice to handle >> Scala types conversions by self when Java programmers prepare to >> invoke Scala libraries. I'm not sure which one is the Java programmers' >> root complaint, Scala type instance or Scala Jar file. >> >> My 2 cents. >> >> -- >> Cheers, >> -z >> >> On Thu, 30 Apr 2020 09:17:37 +0900 >> Hyukjin Kwon <gurwls...@gmail.com> wrote: >> >> > There was a typo in the previous email. I am re-sending: >> > >> > Hm, I thought you meant you prefer 3. over 4 but don't mind >> particularly. >> > I don't mean to wait for more feedback. It looks likely just a deadlock >> > which will be the worst case. >> > I was suggesting to pick one way first, and stick to it. If we find out >> > something later, we can discuss >> > more about changing it later. >> > >> > Having separate Java specific API (3. way) >> > - causes maintenance cost >> > - makes users to search which API for Java every time >> > - this looks the opposite why against the unified API set Spark >> targeted >> > so far. >> > >> > I don't completely buy the argument about Scala/Java friendly because >> using >> > Java instance is already documented in the official Scala documentation. >> > Users still need to search if we have Java specific methods for *some* >> APIs. >> > >> > 2020년 4월 30일 (목) 오전 8:58, Hyukjin Kwon <gurwls...@gmail.com>님이 작성: >> > >> > > Hm, I thought you meant you prefer 3. over 4 but don't mind >> particularly. >> > > I don't mean to wait for more feedback. It looks likely just a >> deadlock >> > > which will be the worst case. >> > > I was suggesting to pick one way first, and stick to it. If we find >> out >> > > something later, we can discuss >> > > more about changing it later. >> > > >> > > Having separate Java specific API (4. way) >> > > - causes maintenance cost >> > > - makes users to search which API for Java every time >> > > - this looks the opposite why against the unified API set Spark >> targeted >> > > so far. >> > > >> > > I don't completely buy the argument about Scala/Java friendly because >> > > using Java instance is already documented in the official Scala >> > > documentation. >> > > Users still need to search if we have Java specific methods for *some* >> > > APIs. >> > > >> > > >> > > >> > > On Thu, 30 Apr 2020, 00:06 Tom Graves, <tgraves...@yahoo.com> wrote: >> > > >> > >> Sorry I'm not sure what your last email means. Does it mean you are >> > >> putting it up for a vote or just waiting to get more feedback? I >> disagree >> > >> with saying option 4 is the rule but agree having a general rule >> makes >> > >> sense. I think we need a lot more input to make the rule as it >> affects the >> > >> api's. >> > >> >> > >> Tom >> > >> >> > >> On Wednesday, April 29, 2020, 09:53:22 AM CDT, Hyukjin Kwon < >> > >> gurwls...@gmail.com> wrote: >> > >> >> > >> >> > >> I think I am not seeing explicit objection here but rather see people >> > >> tend to agree with the proposal in general. >> > >> I would like to step forward rather than leaving it as a deadlock - >> the >> > >> worst choice here is to postpone and abandon this discussion with >> this >> > >> inconsistency. >> > >> >> > >> I don't currently target to document this as the cases are rather >> > >> rare, and we haven't really documented JavaRDD <> RDD vs DataFrame >> case as >> > >> well. >> > >> Let's keep monitoring and see if this discussion thread clarifies >> things >> > >> enough in such cases I mentioned. >> > >> >> > >> Let me know if you guys think differently. >> > >> >> > >> >> > >> 2020년 4월 28일 (화) 오후 5:03, Hyukjin Kwon <gurwls...@gmail.com>님이 작성: >> > >> >> > >> Spark has targeted to have a unified API set rather than having >> separate >> > >> Java classes to reduce the maintenance cost, >> > >> e.g.) JavaRDD <> RDD vs DataFrame. These JavaXXX are more about the >> > >> legacy. >> > >> >> > >> I think it's best to stick to the approach 4. in general cases. >> > >> Other options might have to be considered based upon a specific >> context. >> > >> For example, if we *must* to add a bunch of Java-specifics >> > >> into a specific class for an inevitable reason somewhere, I would >> > >> consider to have a Java-specific class. >> > >> >> > >> >> > >> >> > >> 2020년 4월 28일 (화) 오후 4:38, ZHANG Wei <wezh...@outlook.com>님이 작성: >> > >> >> > >> Be frankly, I also love the pure Java type in Java API and Scala >> type in >> > >> Scala API. :-) >> > >> >> > >> If we don't treat Java as a "FRIEND" of Scala, just as Python, maybe >> we >> > >> can adopt the status of option 1, the specific Java classes. (But I >> don't >> > >> like the `Java` prefix, which is redundant when I'm coding Java app, >> > >> such as JavaRDD, why not distinct it by package namespace...) The >> specific >> > >> Java API can also leverage some native Java language features with >> new >> > >> versions. >> > >> >> > >> And just since the friendly relationship between Scala and Java, the >> Java >> > >> user can call Scala API with `.asScala` or `.asJava`'s help if Java >> API >> > >> is not ready. Then switch to Java API when it's well cooked. >> > >> >> > >> The cons is more efforts to maintain. >> > >> >> > >> My 2 cents. >> > >> >> > >> -- >> > >> Cheers, >> > >> -z >> > >> >> > >> On Tue, 28 Apr 2020 12:07:36 +0900 >> > >> Hyukjin Kwon <gurwls...@gmail.com> wrote: >> > >> >> > >> > The problem is that calling Scala instances in Java side is >> discouraged >> > >> in >> > >> > general up to my best knowledge. >> > >> > A Java user won't likely know asJava in Scala but a Scala user will >> > >> likely >> > >> > know both asScala and asJava. >> > >> > >> > >> > >> > >> > 2020년 4월 28일 (화) 오전 11:35, ZHANG Wei <wezh...@outlook.com>님이 작성: >> > >> > >> > >> > > How about making a small change on option 4: >> > >> > > Keep Scala API returning Scala type instance with providing a >> > >> > > `asJava` method to return a Java type instance. >> > >> > > >> > >> > > Scala 2.13 has provided CollectionConverter [1][2][3], in the >> > >> following >> > >> > > Spark dependences upgrade, which can be supported by nature. For >> > >> > > current Scala 2.12 version, we can wrap >> `ImplicitConversionsToJava`[4] >> > >> > > as what Scala 2.13 does and add implicit conversions. >> > >> > > >> > >> > > Just my 2 cents. >> > >> > > >> > >> > > -- >> > >> > > Cheers, >> > >> > > -z >> > >> > > >> > >> > > [1] >> > >> > > >> > >> >> https://nam12.safelinks.protection.outlook.com/?url=https%3A%2F%2Fdocs.scala-lang.org%2Foverviews%2Fcollections-2.13%2Fconversions-between-java-and-scala-collections.html&data=02%7C01%7C%7C9175b84aa9004ee6da1908d7ec9bea50%7C84df9e7fe9f640afb435aaaaaaaaaaaa%7C1%7C0%7C637238026695625983&sdata=Vw8k4x0D0P1Pocr17O6wPUQzt%2FS3iX0lCBigIKdy0yY%3D&reserved=0 >> > >> > > [2] >> > >> > > >> > >> >> https://nam12.safelinks.protection.outlook.com/?url=https%3A%2F%2Fwww.scala-lang.org%2Fapi%2F2.13.0%2Fscala%2Fjdk%2Fjavaapi%2FCollectionConverters%24.html&data=02%7C01%7C%7C9175b84aa9004ee6da1908d7ec9bea50%7C84df9e7fe9f640afb435aaaaaaaaaaaa%7C1%7C0%7C637238026695625983&sdata=9R96UT1W05Wn6K3RhhkMi1lo6bUnHht3qEhKxsr7%2FI0%3D&reserved=0 >> > >> > > [3] >> > >> > > >> > >> >> https://nam12.safelinks.protection.outlook.com/?url=https%3A%2F%2Fwww.scala-lang.org%2Fapi%2F2.13.0%2Fscala%2Fjdk%2FCollectionConverters%24.html&data=02%7C01%7C%7C9175b84aa9004ee6da1908d7ec9bea50%7C84df9e7fe9f640afb435aaaaaaaaaaaa%7C1%7C0%7C637238026695625983&sdata=IBKGT2uSOgMg0KQOLZnDkxMVeUiZDzEvKvxNF%2FZzXxs%3D&reserved=0 >> > >> > > [4] >> > >> > > >> > >> >> https://nam12.safelinks.protection.outlook.com/?url=https%3A%2F%2Fwww.scala-lang.org%2Fapi%2F2.12.11%2Fscala%2Fcollection%2Fconvert%2FImplicitConversionsToJava%24.html&data=02%7C01%7C%7C9175b84aa9004ee6da1908d7ec9bea50%7C84df9e7fe9f640afb435aaaaaaaaaaaa%7C1%7C0%7C637238026695625983&sdata=nkxkT0WUrqpaOUcyvWDDlFK3yrTa7WJBlTw%2Foqjqqks%3D&reserved=0 >> > >> > > >> > >> > > >> > >> > > On Tue, 28 Apr 2020 08:52:57 +0900 >> > >> > > Hyukjin Kwon <gurwls...@gmail.com> wrote: >> > >> > > >> > >> > > > I would like to make sure I am open for other options that can >> be >> > >> > > > considered situationally and based on the context. >> > >> > > > It's okay, and I don't target to restrict this here. For >> example, >> > >> DSv2, I >> > >> > > > understand it's written in Java because Java >> > >> > > > interfaces arguably brings better performance. That's why >> vectorized >> > >> > > > readers are written in Java too. >> > >> > > > >> > >> > > > Maybe the "general" wasn't explicit in my previous email. >> Adding >> > >> APIs to >> > >> > > > return a Java instance is still >> > >> > > > rather rare in general given my few years monitoring. >> > >> > > > The problem I would more like to deal with is more about when >> we >> > >> need to >> > >> > > > add one or a couple of user-facing >> > >> > > > Java-specific APIs to return Java instances, which is >> relatively >> > >> more >> > >> > > > frequent compared to when we need a bunch >> > >> > > > of Java specific APIs. >> > >> > > > >> > >> > > > In this case, I think it should be guided to use 4. approach. >> There >> > >> are >> > >> > > > pros and cons between 3. and 4., of course. >> > >> > > > But it looks to me 4. approach is closer to what Spark has >> targeted >> > >> so >> > >> > > far. >> > >> > > > >> > >> > > > >> > >> > > > >> > >> > > > 2020년 4월 28일 (화) 오전 8:34, Hyukjin Kwon <gurwls...@gmail.com>님이 >> 작성: >> > >> > > > >> > >> > > > > > One thing we could do here is use Java collections >> internally >> > >> and >> > >> > > make >> > >> > > > > the Scala API a thin wrapper around Java -- like how Python >> works. >> > >> > > > > > Then adding a method to the Scala API would require adding >> it >> > >> to the >> > >> > > > > Java API and we would keep the two more in sync. >> > >> > > > > >> > >> > > > > I think it can be an appropriate idea for when we have to >> deal >> > >> with >> > >> > > this >> > >> > > > > case a lot but I don't think there are so many >> > >> > > > > user-facing APIs to return a Java collections, it's rather >> rare. >> > >> Also, >> > >> > > the >> > >> > > > > Java users are relatively less than Scala users. >> > >> > > > > This case is slightly different from Python in a way that >> there >> > >> are so >> > >> > > > > many differences to deal with in PySpark case. >> > >> > > > > >> > >> > > > > Also, in case of `Seq`, actually we can just use `Array` >> instead >> > >> for >> > >> > > both >> > >> > > > > Scala and Java side simply. I don't find such cases notably >> > >> awkward. >> > >> > > > > This problematic cases might be specific to few Java >> collections >> > >> or >> > >> > > > > instances, and I would like to avoid an overkill here. >> > >> > > > > >> > >> > > > > Of course, if there is a place to consider other options, >> let's >> > >> do. I >> > >> > > > > don't like to say this is the only required option. >> > >> > > > > >> > >> > > > > >> > >> > > > > >> > >> > > > > >> > >> > > > > >> > >> > > > > 2020년 4월 28일 (화) 오전 1:18, Ryan Blue >> <rb...@netflix.com.invalid>님이 >> > >> 작성: >> > >> > > > > >> > >> > > > >> I think the right choice here depends on how the object is >> used. >> > >> For >> > >> > > > >> developer and internal APIs, I think standardizing on Java >> > >> collections >> > >> > > > >> makes the most sense. >> > >> > > > >> >> > >> > > > >> For user-facing APIs, it is awkward to return Java >> collections to >> > >> > > Scala >> > >> > > > >> code -- I think that's the motivation for Tom's comment. >> For user >> > >> > > APIs, I >> > >> > > > >> think most methods should return Scala collections, and I >> don't >> > >> have a >> > >> > > > >> strong opinion about whether the conversion (or lack >> thereof) is >> > >> done >> > >> > > in a >> > >> > > > >> separate object (#1) or in parallel methods (#3). >> > >> > > > >> >> > >> > > > >> Both #1 and #3 seem like about the same amount of work and >> have >> > >> the >> > >> > > same >> > >> > > > >> likelihood that a developer will leave out a Java method >> > >> version. One >> > >> > > thing >> > >> > > > >> we could do here is use Java collections internally and >> make the >> > >> > > Scala API >> > >> > > > >> a thin wrapper around Java -- like how Python works. Then >> adding >> > >> a >> > >> > > method >> > >> > > > >> to the Scala API would require adding it to the Java API >> and we >> > >> would >> > >> > > keep >> > >> > > > >> the two more in sync. It would also help avoid Scala >> collections >> > >> > > leaking >> > >> > > > >> into internals. >> > >> > > > >> >> > >> > > > >> On Mon, Apr 27, 2020 at 8:49 AM Hyukjin Kwon < >> > >> gurwls...@gmail.com> >> > >> > > wrote: >> > >> > > > >> >> > >> > > > >>> Let's stick to the less maintenance efforts then rather >> than we >> > >> > > leave it >> > >> > > > >>> undecided and delay with leaving this inconsistency. >> > >> > > > >>> >> > >> > > > >>> I dont think we can have some very meaningful data about >> this >> > >> soon >> > >> > > given >> > >> > > > >>> that we don't hear much complaints about this in general >> so far. >> > >> > > > >>> >> > >> > > > >>> The point of this thread is to make a call rather then >> defer to >> > >> the >> > >> > > > >>> future. >> > >> > > > >>> >> > >> > > > >>> On Mon, 27 Apr 2020, 23:15 Wenchen Fan, < >> cloud0...@gmail.com> >> > >> wrote: >> > >> > > > >>> >> > >> > > > >>>> IIUC We are moving away from having 2 classes for Java and >> > >> Scala, >> > >> > > like >> > >> > > > >>>> JavaRDD and RDD. It's much simpler to maintain and use >> with a >> > >> > > single class. >> > >> > > > >>>> >> > >> > > > >>>> I don't have a strong preference over option 3 or 4. We >> may >> > >> need to >> > >> > > > >>>> collect more data points from actual users. >> > >> > > > >>>> >> > >> > > > >>>> On Mon, Apr 27, 2020 at 9:50 PM Hyukjin Kwon < >> > >> gurwls...@gmail.com> >> > >> > > > >>>> wrote: >> > >> > > > >>>> >> > >> > > > >>>>> Scala users are arguably more prevailing compared to Java >> > >> users, >> > >> > > yes. >> > >> > > > >>>>> Using the Java instances in Scala side is legitimate, and >> > >> they are >> > >> > > > >>>>> already being used in multiple please. I don't believe >> Scala >> > >> > > > >>>>> users find this not Scala friendly as it's legitimate and >> > >> already >> > >> > > > >>>>> being used. I personally find it's more trouble some to >> let >> > >> Java >> > >> > > > >>>>> users to search which APIs to call. Yes, I understand the >> > >> pros and >> > >> > > > >>>>> cons - we should also find the balance considering the >> actual >> > >> > > usage. >> > >> > > > >>>>> >> > >> > > > >>>>> One more argument from me is, though, I think one of the >> > >> goals in >> > >> > > > >>>>> Spark APIs is the unified API set up to my knowledge >> > >> > > > >>>>> e.g., JavaRDD <> RDD vs DataFrame. >> > >> > > > >>>>> If either way is not particularly preferred over the >> other, I >> > >> would >> > >> > > > >>>>> just choose the one to have the unified API set. >> > >> > > > >>>>> >> > >> > > > >>>>> >> > >> > > > >>>>> >> > >> > > > >>>>> 2020년 4월 27일 (월) 오후 10:37, Tom Graves < >> tgraves...@yahoo.com>님이 >> > >> 작성: >> > >> > > > >>>>> >> > >> > > > >>>>>> I agree a general guidance is good so we keep >> consistent in >> > >> the >> > >> > > apis. >> > >> > > > >>>>>> I don't necessarily agree that 4 is the best solution >> > >> though. I >> > >> > > agree its >> > >> > > > >>>>>> nice to have one api, but it is less friendly for the >> scala >> > >> side. >> > >> > > > >>>>>> Searching for the equivalent Java api shouldn't be hard >> as it >> > >> > > should be >> > >> > > > >>>>>> very close in the name and if we make it a general rule >> users >> > >> > > should >> > >> > > > >>>>>> understand it. I guess one good question is what API >> do >> > >> most of >> > >> > > our users >> > >> > > > >>>>>> use between Java and Scala and what is the ratio? I >> don't >> > >> know >> > >> > > the answer >> > >> > > > >>>>>> to that. I've seen more using Scala over Java. If the >> > >> majority >> > >> > > use Scala >> > >> > > > >>>>>> then I think the API should be more friendly to that. >> > >> > > > >>>>>> >> > >> > > > >>>>>> Tom >> > >> > > > >>>>>> >> > >> > > > >>>>>> On Monday, April 27, 2020, 04:04:28 AM CDT, Hyukjin >> Kwon < >> > >> > > > >>>>>> gurwls...@gmail.com> wrote: >> > >> > > > >>>>>> >> > >> > > > >>>>>> >> > >> > > > >>>>>> Hi all, >> > >> > > > >>>>>> >> > >> > > > >>>>>> I would like to discuss Java specific APIs and which >> design >> > >> we >> > >> > > will >> > >> > > > >>>>>> choose. >> > >> > > > >>>>>> This has been discussed in multiple places so far, for >> > >> example, at >> > >> > > > >>>>>> >> > >> >> https://nam12.safelinks.protection.outlook.com/?url=https%3A%2F%2Fgithub.com%2Fapache%2Fspark%2Fpull%2F28085%23discussion_r407334754&data=02%7C01%7C%7C9175b84aa9004ee6da1908d7ec9bea50%7C84df9e7fe9f640afb435aaaaaaaaaaaa%7C1%7C0%7C637238026695625983&sdata=zEYDV0XyvDbeL5YojcdZWHfuJ%2BVOP5%2ByFlbkTFlHPGM%3D&reserved=0 >> > >> > > > >>>>>> >> > >> > > > >>>>>> >> > >> > > > >>>>>> *The problem:* >> > >> > > > >>>>>> >> > >> > > > >>>>>> In short, I would like us to have clear guidance on how >> we >> > >> support >> > >> > > > >>>>>> Java specific APIs when >> > >> > > > >>>>>> it requires to return a Java instance. The problem is >> simple: >> > >> > > > >>>>>> >> > >> > > > >>>>>> def requests: Map[String, ExecutorResourceRequest] = ... >> > >> > > > >>>>>> def requestsJMap: java.util.Map[String, >> > >> ExecutorResourceRequest] >> > >> > > = ... >> > >> > > > >>>>>> >> > >> > > > >>>>>> vs >> > >> > > > >>>>>> >> > >> > > > >>>>>> def requests: java.util.Map[String, >> ExecutorResourceRequest] >> > >> = ... >> > >> > > > >>>>>> >> > >> > > > >>>>>> >> > >> > > > >>>>>> *Current codebase:* >> > >> > > > >>>>>> >> > >> > > > >>>>>> My understanding so far was that the latter is >> preferred and >> > >> more >> > >> > > > >>>>>> consistent and prevailing in the >> > >> > > > >>>>>> existing codebase, for example, see >> StateOperatorProgress and >> > >> > > > >>>>>> StreamingQueryProgress in Structured Streaming. >> > >> > > > >>>>>> However, I realised that we also have other approaches >> in the >> > >> > > current >> > >> > > > >>>>>> codebase. There look >> > >> > > > >>>>>> four approaches to deal with Java specifics in general: >> > >> > > > >>>>>> >> > >> > > > >>>>>> 1. Java specific classes such as JavaRDD and >> > >> JavaSparkContext. >> > >> > > > >>>>>> 2. Java specific methods with the same name that >> overload >> > >> its >> > >> > > > >>>>>> parameters, see functions.scala. >> > >> > > > >>>>>> 3. Java specific methods with a different name that >> needs >> > >> to >> > >> > > > >>>>>> return a different type such as >> TaskContext.resourcesJMap >> > >> vs >> > >> > > > >>>>>> TaskContext.resources. >> > >> > > > >>>>>> 4. One method that returns a Java instance for both >> Scala >> > >> and >> > >> > > > >>>>>> Java sides. see StateOperatorProgress and >> > >> > > StreamingQueryProgress. >> > >> > > > >>>>>> >> > >> > > > >>>>>> >> > >> > > > >>>>>> *Analysis on the current codebase:* >> > >> > > > >>>>>> >> > >> > > > >>>>>> I agree with 2. approach because the corresponding cases >> > >> give you >> > >> > > a >> > >> > > > >>>>>> consistent API usage across >> > >> > > > >>>>>> other language APIs in general. Approach 1. is from the >> old >> > >> world >> > >> > > > >>>>>> when we didn't have unified APIs. >> > >> > > > >>>>>> This might be the worst approach. >> > >> > > > >>>>>> >> > >> > > > >>>>>> 3. and 4. are controversial. >> > >> > > > >>>>>> >> > >> > > > >>>>>> For 3., if you have to use Java APIs, then, you should >> > >> search if >> > >> > > > >>>>>> there is a variant of that API >> > >> > > > >>>>>> every time specifically for Java APIs. But yes, it >> gives you >> > >> > > > >>>>>> Java/Scala friendly instances. >> > >> > > > >>>>>> >> > >> > > > >>>>>> For 4., having one API that returns a Java instance >> makes you >> > >> > > able to >> > >> > > > >>>>>> use it in both Scala and Java APIs >> > >> > > > >>>>>> sides although it makes you call asScala in Scala side >> > >> > > specifically. >> > >> > > > >>>>>> But you don’t >> > >> > > > >>>>>> have to search if there’s a variant of this API and it >> gives >> > >> you a >> > >> > > > >>>>>> consistent API usage across languages. >> > >> > > > >>>>>> >> > >> > > > >>>>>> Also, note that calling Java in Scala is legitimate but >> the >> > >> > > opposite >> > >> > > > >>>>>> case is not, up to my best knowledge. >> > >> > > > >>>>>> In addition, you should have a method that returns a >> Java >> > >> instance >> > >> > > > >>>>>> for PySpark or SparkR to support. >> > >> > > > >>>>>> >> > >> > > > >>>>>> >> > >> > > > >>>>>> *Proposal:* >> > >> > > > >>>>>> >> > >> > > > >>>>>> I would like to have a general guidance on this that the >> > >> Spark dev >> > >> > > > >>>>>> agrees upon: Do 4. approach. If not possible, do 3. >> Avoid 1 >> > >> > > almost at all >> > >> > > > >>>>>> cost. >> > >> > > > >>>>>> >> > >> > > > >>>>>> Note that this isn't a hard requirement but *a general >> > >> guidance*; >> > >> > > > >>>>>> therefore, the decision might be up to >> > >> > > > >>>>>> the specific context. For example, when there are some >> strong >> > >> > > > >>>>>> arguments to have a separate Java specific API, that’s >> fine. >> > >> > > > >>>>>> Of course, we won’t change the existing methods given >> > >> Micheal’s >> > >> > > > >>>>>> rubric added before. I am talking about new >> > >> > > > >>>>>> methods in unreleased branches. >> > >> > > > >>>>>> >> > >> > > > >>>>>> Any concern or opinion on this? >> > >> > > > >>>>>> >> > >> > > > >>>>> >> > >> > > > >> >> > >> > > > >> -- >> > >> > > > >> Ryan Blue >> > >> > > > >> Software Engineer >> > >> > > > >> Netflix >> > >> > > > >> >> > >> > > > > >> > >> > > >> > >> >> > >> >> >>
