JEP 442: Foreign Function & Memory API => why is it again preview API?

[Remi Forax]

----- Original Message -----
> From: "Uwe Schindler" <uschindler at apache.org>
> To: "core-libs-dev" <core-libs-dev at openjdk.org>
> Sent: Tuesday, May 16, 2023 5:38:32 PM
> Subject: JEP 442: Foreign Function & Memory API => why is it again preview API?

> Hi,

Hi Uwe,

> 
> yesterday Apache Lucene got the information that JDK 21 got the project
> panama JEP 442 update and I implemented it already in our source tree.
> 
> Unfortunately the API is again marked "preview", but JDK 21 is "LTS
> release". Many of our users (Elasticserach, Solr) will be switching to
> this version. We were really hoping that the java.lang.foreign API is
> finished at that time. I checked the changes in our code: just a rename
> of a method and FileChannel#map now takes Arena instead of Scope.

I see that Alan and Maurizio have already answer to your other points.

Having preview features and being a LTS are to separate concerns.
Being a LTS is about support, having preview features is about having feedback before finalizing an API.

Java 17 was released with preview features, Java 21 will be.

Before Java 10, when we were doing feature release model, if a feature was not ready yet, either the release was delayed (Java 9 was delayed 3 times if i'm remembering correctly) or postponed to the next big release (Java Module was initially scheduled for Java 8). With the new cadence model, features that are not ready yet are marked as preview.

I understand that you are eager to use MemorySegment in anger but since a looong time, Java features are only released when they are ready :)

Also, it seems that we will have a LTS release every two years now, if a LTS had no preview, it means that we will not get any feedback for 1/4 of the releases.

> 
> Uwe
> 

regards,
Rémi

> 
> --
> Uwe Schindler
> uschindler at apache.org
> ASF Member, Member of PMC and Committer of Apache Lucene and Apache Solr
> Bremen, Germany
> https://lucene.apache.org/
> https://solr.apache.org/