spark-dev mailing list archives

Site index · List index
Message view « Date » · « Thread »
Top « Date » · « Thread »
From Marco Gaido <marcogaid...@gmail.com>
Subject Re: [DISCUSS] Spark 2.5 release
Date Sun, 22 Sep 2019 05:59:12 GMT
I agree with Matei too.

Thanks,
Marco

Il giorno dom 22 set 2019 alle ore 03:44 Dongjoon Hyun <
dongjoon.hyun@gmail.com> ha scritto:

> +1 for Matei's suggestion!
>
> Bests,
> Dongjoon.
>
> On Sat, Sep 21, 2019 at 5:44 PM Matei Zaharia <matei.zaharia@gmail.com>
> wrote:
>
>> If the goal is to get people to try the DSv2 API and build DSv2 data
>> sources, can we recommend the 3.0-preview release for this? That would get
>> people shifting to 3.0 faster, which is probably better overall compared to
>> maintaining two major versions. There’s not that much else changing in 3.0
>> if you already want to update your Java version.
>>
>> On Sep 21, 2019, at 2:45 PM, Ryan Blue <rblue@netflix.com.INVALID> wrote:
>>
>> > If you insist we shouldn't change the unstable temporary API in 3.x . .
>> .
>>
>> Not what I'm saying at all. I said we should carefully consider whether a
>> breaking change is the right decision in the 3.x line.
>>
>> All I'm suggesting is that we can make a 2.5 release with the feature and
>> an API that is the same as the one in 3.0.
>>
>> > I also don't get this backporting a giant feature to 2.x line
>>
>> I am planning to do this so we can use DSv2 before 3.0 is released. Then
>> we can have a source implementation that works in both 2.x and 3.0 to make
>> the transition easier. Since I'm already doing the work, I'm offering to
>> share it with the community.
>>
>>
>> On Sat, Sep 21, 2019 at 2:36 PM Reynold Xin <rxin@databricks.com> wrote:
>>
>>> Because for example we'd need to move the location of InternalRow,
>>> breaking the package name. If you insist we shouldn't change the unstable
>>> temporary API in 3.x to maintain compatibility with 3.0, which is totally
>>> different from my understanding of the situation when you exposed it, then
>>> I'd say we should gate 3.0 on having a stable row interface.
>>>
>>> I also don't get this backporting a giant feature to 2.x line ... as
>>> suggested by others in the thread, DSv2 would be one of the main reasons
>>> people upgrade to 3.0. What's so special about DSv2 that we are doing this?
>>> Why not abandoning 3.0 entirely and backport all the features to 2.x?
>>>
>>>
>>>
>>> On Sat, Sep 21, 2019 at 2:31 PM, Ryan Blue <rblue@netflix.com> wrote:
>>>
>>>> Why would that require an incompatible change?
>>>>
>>>> We *could* make an incompatible change and remove support for
>>>> InternalRow, but I think we would want to carefully consider whether that
>>>> is the right decision. And in any case, we would be able to keep 2.5 and
>>>> 3.0 compatible, which is the main goal.
>>>>
>>>> On Sat, Sep 21, 2019 at 2:28 PM Reynold Xin <rxin@databricks.com>
>>>> wrote:
>>>>
>>>> How would you not make incompatible changes in 3.x? As discussed the
>>>> InternalRow API is not stable and needs to change.
>>>>
>>>> On Sat, Sep 21, 2019 at 2:27 PM Ryan Blue <rblue@netflix.com> wrote:
>>>>
>>>> > Making downstream to diverge their implementation heavily between
>>>> minor versions (say, 2.4 vs 2.5) wouldn't be a good experience
>>>>
>>>> You're right that the API has been evolving in the 2.x line. But, it is
>>>> now reasonably stable with respect to the current feature set and we should
>>>> not need to break compatibility in the 3.x line. Because we have reached
>>>> our goals for the 3.0 release, we can backport at least those features to
>>>> 2.x and confidently have an API that works in both a 2.x release and is
>>>> compatible with 3.0, if not 3.1 and later releases as well.
>>>>
>>>> > I'd rather say preparation of Spark 2.5 should be started after Spark
>>>> 3.0 is officially released
>>>>
>>>> The reason I'm suggesting this is that I'm already going to do the work
>>>> to backport the 3.0 release features to 2.4. I've been asked by several
>>>> people when DSv2 will be released, so I know there is a lot of interest in
>>>> making this available sooner than 3.0. If I'm already doing the work, then
>>>> I'd be happy to share that with the community.
>>>>
>>>> I don't see why 2.5 and 3.0 are mutually exclusive. We can work on 2.5
>>>> while preparing the 3.0 preview and fixing bugs. For DSv2, the work is
>>>> about complete so we can easily release the same set of features and API
in
>>>> 2.5 and 3.0.
>>>>
>>>> If we decide for some reason to wait until after 3.0 is released, I
>>>> don't know that there is much value in a 2.5. The purpose is to be a step
>>>> toward 3.0, and releasing that step after 3.0 doesn't seem helpful to me.
>>>> It also wouldn't get these features out any sooner than 3.0, as a 2.5
>>>> release probably would, given the work needed to validate the incompatible
>>>> changes in 3.0.
>>>>
>>>> > DSv2 change would be the major backward incompatibility which Spark
>>>> 2.x users may hesitate to upgrade
>>>>
>>>> As I pointed out, DSv2 has been changing in the 2.x line, so this is
>>>> expected. I don't think it will need incompatible changes in the 3.x line.
>>>>
>>>> On Fri, Sep 20, 2019 at 9:25 PM Jungtaek Lim <kabhwan@gmail.com> wrote:
>>>>
>>>> Just 2 cents, I haven't tracked the change of DSv2 (though I needed to
>>>> deal with this as the change made confusion on my PRs...), but my bet is
>>>> that DSv2 would be already changed in incompatible way, at least who works
>>>> for custom DataSource. Making downstream to diverge their implementation
>>>> heavily between minor versions (say, 2.4 vs 2.5) wouldn't be a good
>>>> experience - especially we are not completely closed the chance to further
>>>> modify DSv2, and the change could be backward incompatible.
>>>>
>>>> If we really want to bring the DSv2 change to 2.x version line to let
>>>> end users avoid forcing to upgrade Spark 3.x to enjoy new DSv2, I'd rather
>>>> say preparation of Spark 2.5 should be started after Spark 3.0 is
>>>> officially released, honestly even later than that, say, getting some
>>>> reports from Spark 3.0 about DSv2 so that we feel DSv2 is OK. I hope we
>>>> don't make Spark 2.5 be a kind of "tech-preview" which Spark 2.4 users may
>>>> be frustrated to upgrade to next minor version.
>>>>
>>>> Btw, do we have any specific target users for this? Personally DSv2
>>>> change would be the major backward incompatibility which Spark 2.x users
>>>> may hesitate to upgrade, so they might be already prepared to migrate to
>>>> Spark 3.0 if they are prepared to migrate to new DSv2.
>>>>
>>>> On Sat, Sep 21, 2019 at 12:46 PM Dongjoon Hyun <dongjoon.hyun@gmail.com>
>>>> wrote:
>>>>
>>>> Do you mean you want to have a breaking API change between 3.0 and 3.1?
>>>> I believe we follow Semantic Versioning (
>>>> https://spark.apache.org/versioning-policy.html ).
>>>>
>>>> > We just won’t add any breaking changes before 3.1.
>>>>
>>>> Bests,
>>>> Dongjoon.
>>>>
>>>>
>>>> On Fri, Sep 20, 2019 at 11:48 AM Ryan Blue <rblue@netflix.com.invalid>
>>>> wrote:
>>>>
>>>> I don’t think we need to gate a 3.0 release on making a more stable
>>>> version of InternalRow
>>>>
>>>> Sounds like we agree, then. We will use it for 3.0, but there are known
>>>> problems with it.
>>>>
>>>> Thinking we’d have dsv2 working in both 3.x (which will change and
>>>> progress towards more stable, but will have to break certain APIs) and 2.x
>>>> seems like a false premise.
>>>>
>>>> Why do you think we will need to break certain APIs before 3.0?
>>>>
>>>> I’m only suggesting that we release the same support in a 2.5 release
>>>> that we do in 3.0. Since we are nearly finished with the 3.0 goals, it
>>>> seems like we can certainly do that. We just won’t add any breaking changes
>>>> before 3.1.
>>>>
>>>> On Fri, Sep 20, 2019 at 11:39 AM Reynold Xin <rxin@databricks.com>
>>>> wrote:
>>>>
>>>> I don't think we need to gate a 3.0 release on making a more stable
>>>> version of InternalRow, but thinking we'd have dsv2 working in both 3.x
>>>> (which will change and progress towards more stable, but will have to break
>>>> certain APIs) and 2.x seems like a false premise.
>>>>
>>>> To point out some problems with InternalRow that you think are already
>>>> pragmatic and stable:
>>>>
>>>> The class is in catalyst, which states:
>>>> https://github.com/apache/spark/blob/master/sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/package.scala
>>>>
>>>> /**
>>>> * Catalyst is a library for manipulating relational query plans.  All
>>>> classes in catalyst are
>>>> * considered an internal API to Spark SQL and are subject to change
>>>> between minor releases.
>>>> */
>>>>
>>>> There is no even any annotation on the interface.
>>>>
>>>> The entire dependency chain were created to be private, and tightly
>>>> coupled with internal implementations. For example,
>>>>
>>>>
>>>> https://github.com/apache/spark/blob/master/common/unsafe/src/main/java/org/apache/spark/unsafe/types/UTF8String.java
>>>>
>>>> /**
>>>> * A UTF-8 String for internal Spark use.
>>>> * <p>
>>>> * A String encoded in UTF-8 as an Array[Byte], which can be used for
>>>> comparison,
>>>> * search, see http://en.wikipedia.org/wiki/UTF-8 for details.
>>>> * <p>
>>>> * Note: This is not designed for general use cases, should not be used
>>>> outside SQL.
>>>> */
>>>>
>>>>
>>>>
>>>> https://github.com/apache/spark/blob/master/sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/util/ArrayData.scala
>>>>
>>>> (which again is in catalyst package)
>>>>
>>>>
>>>> If you want to argue this way, you might as well argue we should make
>>>> the entire catalyst package public to be pragmatic and not allow any
>>>> changes.
>>>>
>>>>
>>>>
>>>>
>>>> On Fri, Sep 20, 2019 at 11:32 AM, Ryan Blue <rblue@netflix.com> wrote:
>>>>
>>>> When you created the PR to make InternalRow public
>>>>
>>>> This isn’t quite accurate. The change I made was to use InternalRow
>>>> instead of UnsafeRow, which is a specific implementation of InternalRow.
>>>> Exposing this API has always been a part of DSv2 and while both you and I
>>>> did some work to avoid this, we are still in the phase of starting with
>>>> that API.
>>>>
>>>> Note that any change to InternalRow would be very costly to implement
>>>> because this interface is widely used. That is why I think we can certainly
>>>> consider it stable enough to use here, and that’s probably why
>>>> UnsafeRow was part of the original proposal.
>>>>
>>>> In any case, the goal for 3.0 was not to replace the use of InternalRow,
>>>> it was to get the majority of SQL working on top of the interface added
>>>> after 2.4. That’s done and stable, so I think a 2.5 release with it is
also
>>>> reasonable.
>>>>
>>>> On Fri, Sep 20, 2019 at 11:23 AM Reynold Xin <rxin@databricks.com>
>>>> wrote:
>>>>
>>>> To push back, while I agree we should not drastically change
>>>> "InternalRow", there are a lot of changes that need to happen to make it
>>>> stable. For example, none of the publicly exposed interfaces should be in
>>>> the Catalyst package or the unsafe package. External implementations should
>>>> be decoupled from the internal implementations, with cheap ways to convert
>>>> back and forth.
>>>>
>>>> When you created the PR to make InternalRow public, the understanding
>>>> was to work towards making it stable in the future, assuming we will start
>>>> with an unstable API temporarily. You can't just make a bunch internal APIs
>>>> tightly coupled with other internal pieces public and stable and call it
a
>>>> day, just because it happen to satisfy some use cases temporarily assuming
>>>> the rest of Spark doesn't change.
>>>>
>>>>
>>>>
>>>> On Fri, Sep 20, 2019 at 11:19 AM, Ryan Blue <rblue@netflix.com> wrote:
>>>>
>>>> > DSv2 is far from stable right?
>>>>
>>>> No, I think it is reasonably stable and very close to being ready for a
>>>> release.
>>>>
>>>> > All the actual data types are unstable and you guys have completely
>>>> ignored that.
>>>>
>>>> I think what you're referring to is the use of `InternalRow`. That's a
>>>> stable API and there has been no work to avoid using it. In any case, I
>>>> don't think that anyone is suggesting that we delay 3.0 until a replacement
>>>> for `InternalRow` is added, right?
>>>>
>>>> While I understand the motivation for a better solution here, I think
>>>> the pragmatic solution is to continue using `InternalRow`.
>>>>
>>>> > If the goal is to make DSv2 work across 3.x and 2.x, that seems too
>>>> invasive of a change to backport once you consider the parts needed to make
>>>> dsv2 stable.
>>>>
>>>> I believe that those of us working on DSv2 are confident about the
>>>> current stability. We set goals for what to get into the 3.0 release months
>>>> ago and have very nearly reached the point where we are ready for that
>>>> release.
>>>>
>>>> I don't think instability would be a problem in maintaining
>>>> compatibility between the 2.5 version and the 3.0 version. If we find that
>>>> we need to make API changes (other than additions) then we can make those
>>>> in the 3.1 release. Because the goals we set for the 3.0 release have been
>>>> reached with the current API and if we are ready to release 3.0, we can
>>>> release a 2.5 with the same API.
>>>>
>>>> On Fri, Sep 20, 2019 at 11:05 AM Reynold Xin <rxin@databricks.com>
>>>> wrote:
>>>>
>>>> DSv2 is far from stable right? All the actual data types are unstable
>>>> and you guys have completely ignored that. We'd need to work on that and
>>>> that will be a breaking change. If the goal is to make DSv2 work across 3.x
>>>> and 2.x, that seems too invasive of a change to backport once you consider
>>>> the parts needed to make dsv2 stable.
>>>>
>>>>
>>>>
>>>> On Fri, Sep 20, 2019 at 10:47 AM, Ryan Blue <rblue@netflix.com.invalid>
>>>> wrote:
>>>>
>>>> Hi everyone,
>>>>
>>>> In the DSv2 sync this week, we talked about a possible Spark 2.5
>>>> release based on the latest Spark 2.4, but with DSv2 and Java 11 support
>>>> added.
>>>>
>>>> A Spark 2.5 release with these two additions will help people migrate
>>>> to Spark 3.0 when it is released because they will be able to use a single
>>>> implementation for DSv2 sources that works in both 2.5 and 3.0. Similarly,
>>>> upgrading to 3.0 won't also require also updating to Java 11 because users
>>>> could update to Java 11 with the 2.5 release and have fewer major changes.
>>>>
>>>> Another reason to consider a 2.5 release is that many people are
>>>> interested in a release with the latest DSv2 API and support for DSv2 SQL.
>>>> I'm already going to be backporting DSv2 support to the Spark 2.4 line, so
>>>> it makes sense to share this work with the community.
>>>>
>>>> This release line would just consist of backports like DSv2 and Java 11
>>>> that assist compatibility, to keep the scope of the release small. The
>>>> purpose is to assist people moving to 3.0 and not distract from the 3.0
>>>> release.
>>>>
>>>> Would a Spark 2.5 release help anyone else? Are there any concerns
>>>> about this plan?
>>>>
>>>>
>>>> rb
>>>>
>>>>
>>>> --
>>>> Ryan Blue
>>>> Software Engineer
>>>> Netflix
>>>>
>>>>
>>>>
>>>>
>>>> --
>>>> Ryan Blue
>>>> Software Engineer
>>>> Netflix
>>>>
>>>>
>>>>
>>>>
>>>> --
>>>> Ryan Blue
>>>> Software Engineer
>>>> Netflix
>>>>
>>>>
>>>>
>>>>
>>>> --
>>>> Ryan Blue
>>>> Software Engineer
>>>> Netflix
>>>>
>>>>
>>>>
>>>> --
>>>> Name : Jungtaek Lim
>>>> Blog : http://medium.com/@heartsavior
>>>> Twitter : http://twitter.com/heartsavior
>>>> LinkedIn : http://www.linkedin.com/in/heartsavior
>>>>
>>>>
>>>>
>>>> --
>>>> Ryan Blue
>>>> Software Engineer
>>>> Netflix
>>>>
>>>>
>>>>
>>>> --
>>>> Ryan Blue
>>>> Software Engineer
>>>> Netflix
>>>>
>>>
>>>
>>
>> --
>> Ryan Blue
>> Software Engineer
>> Netflix
>>
>>
>>

Mime
View raw message