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From Holden Karau <hol...@pigscanfly.ca>
Subject Re: Scala 2.12 support
Date Wed, 06 Jun 2018 18:33:36 GMT
Just chatted with Dean @ the summit and it sounds like from Adriaan there
is a fix in 2.13 for the API change issue that could be back ported to 2.12
so how about we try and get this ball rolling?

It sounds like it would also need a closure cleaner change, which could be
backwards compatible but since it’s such a core component and we might want
to be cautious with it, we could when building for 2.11 use the old cleaner
code and for 2.12 use the new code so we don’t break anyone.

How do folks feel about this?

On Sat, Apr 21, 2018 at 5:32 AM Dean Wampler <deanwampler@gmail.com> wrote:

> Hi, Reynold,
>
> Sorry for the delay in replying; I was traveling.
>
> The Scala changes would avoid the need to change the API now. Basically,
> the compiler would be modified to detect the particular case of the two
> ambiguous, overloaded methods, then pick the best fit in a more
> "intelligent" way. (They can provide more specific details). This would not
> address the closure cleaner changes required. However, the Scala team
> offered to provide suggestions or review changes.
>
> dean
>
>
> *Dean Wampler, Ph.D.*
>
> *VP, Fast Data Engineering at Lightbend*
> Author: Programming Scala, 2nd Edition
> <http://shop.oreilly.com/product/0636920033073.do>, Fast Data
> Architectures for Streaming Applications
> <http://www.oreilly.com/data/free/fast-data-architectures-for-streaming-applications.csp>,
> and other content from O'Reilly
> @deanwampler <http://twitter.com/deanwampler>
> http://polyglotprogramming.com
> https://github.com/deanwampler
>
> On Thu, Apr 19, 2018 at 6:46 PM, Reynold Xin <rxin@databricks.com> wrote:
>
>> Forking the thread to focus on Scala 2.12.
>>
>> Dean,
>>
>> There are couple different issues with Scala 2.12 (closure cleaner, API
>> breaking changes). Which one do you think we can address with a Scala
>> upgrade? (The closure cleaner one I haven't spent a lot of time looking at
>> it but it might involve more Spark side changes)
>>
>> On Thu, Apr 19, 2018 at 3:28 AM, Dean Wampler <deanwampler@gmail.com>
>> wrote:
>>
>>> I spoke with Martin Odersky and Lightbend's Scala Team about the known
>>> API issue with method disambiguation. They offered to implement a small
>>> patch in a new release of Scala 2.12 to handle the issue without requiring
>>> a Spark API change. They would cut a 2.12.6 release for it. I'm told that
>>> Scala 2.13 should already handle the issue without modification (it's not
>>> yet released, to be clear). They can also offer feedback on updating the
>>> closure cleaner.
>>>
>>> So, this approach would support Scala 2.12 in Spark, but limited to
>>> 2.12.6+, without the API change requirement, but the closure cleaner would
>>> still need updating. Hence, it could be done for Spark 2.X.
>>>
>>> Let me if you want to pursue this approach.
>>>
>>> dean
>>>
>>>
>>>
>>>
>>> *Dean Wampler, Ph.D.*
>>>
>>> *VP, Fast Data Engineering at Lightbend*
>>> Author: Programming Scala, 2nd Edition
>>> <http://shop.oreilly.com/product/0636920033073.do>, Fast Data
>>> Architectures for Streaming Applications
>>> <http://www.oreilly.com/data/free/fast-data-architectures-for-streaming-applications.csp>,
>>> and other content from O'Reilly
>>> @deanwampler <http://twitter.com/deanwampler>
>>> http://polyglotprogramming.com
>>> https://github.com/deanwampler
>>>
>>> On Thu, Apr 5, 2018 at 8:13 PM, Marcelo Vanzin <vanzin@cloudera.com>
>>> wrote:
>>>
>>>> On Thu, Apr 5, 2018 at 10:30 AM, Matei Zaharia <matei.zaharia@gmail.com>
>>>> wrote:
>>>> > Sorry, but just to be clear here, this is the 2.12 API issue:
>>>> https://issues.apache.org/jira/browse/SPARK-14643, with more details
>>>> in this doc:
>>>> https://docs.google.com/document/d/1P_wmH3U356f079AYgSsN53HKixuNdxSEvo8nw_tgLgM/edit
>>>> .
>>>> >
>>>> > Basically, if we are allowed to change Spark’s API a little to have
>>>> only one version of methods that are currently overloaded between Java and
>>>> Scala, we can get away with a single source three for all Scala versions
>>>> and Java ABI compatibility against any type of Spark (whether using Scala
>>>> 2.11 or 2.12).
>>>>
>>>> Fair enough. To play devil's advocate, most of those methods seem to
>>>> be marked "Experimental / Evolving", which could be used as a reason
>>>> to change them for this purpose in a minor release.
>>>>
>>>> Not all of them are, though (e.g. foreach / foreachPartition are not
>>>> experimental).
>>>>
>>>> --
>>>> Marcelo
>>>>
>>>> ---------------------------------------------------------------------
>>>> To unsubscribe e-mail: dev-unsubscribe@spark.apache.org
>>>>
>>>>
>>>
>>
> --
Twitter: https://twitter.com/holdenkarau

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