New subject: [External] : Re: JDK 23 Feature Freeze / New Loom EA builds

Friday, 14 June 2024

Hey David,

Since it's been a while, I'll confirm all is well on Hibernate projects:

Hibernate ORM: Version 6.6 tested against JDK 23 (EA 26) / 24 (EA 1). No
problems to report.

Hibernate Validator: Version 8.0 tested against JDK 23 (EA 26) / 24 (EA 1).
No problems to report.

Hibernate Search: Version 7.2 tested against JDK 23 (EA 26) / 24 (EA 1). No
problems to report.

Hibernate Reactive: Version 2.3 tested against JDK 23 (EA 26) / 24 (EA 1).
No problems to report.

Have a nice day,

Yoann Rodière
Hibernate Team
yoann(a)hibernate.org

On Mon, Jun 10, 2024 at 11:05 AM David Delabassee via hibernate-dev <
hibernate-dev(a)lists.jboss.org&gt; wrote:

...
 Welcome to the latest OpenJDK Quality Outreach update!

 JDK 23, scheduled for General Availability on September 17, 2024, is now
 in Rampdown Phase One (RDP1) [1]. At this point, the overall JDK 23 feature
 set is frozen (see the final list of JEPs integrated into JDK 23 below) and
 only low-risk enhancements might still be considered. The coming weeks
 should be leveraged to identify and resolve as many issues as possible,
 i.e. before JDK 23 enters the Release Candidates phase in early August [2].
 We count on you to test your projects and help us make JDK 23 another solid
 release!

 This time, we are covering several heads-up related to JDK 23 : Deprecate
 the Memory-Access Methods in sun.misc.Unsafe for Removal and default
 annotation processing policy change. Also, make sure to check the new Loom
 early-access builds which have an improved Java monitors implementation to
 work better with virtual threads.

 [1] https://mail.openjdk.org/pipermail/jdk-dev/2024-June/009053.html
 [2] https://openjdk.org/projects/jdk/23/

 ## Heads-Up - JDK 23: Deprecate the Memory-Access Methods in
 sun.misc.Unsafe for Removal

 As mentioned in a previous communication [3], there’s a plan to ultimately
 remove the sun.misc.Unsafe memory-access methods as the platform offers
 safer alternatives. JEP 471 (Deprecate the Memory-Access Methods in
 sun.misc.Unsafe for Removal) [4] outlines in more detail this plan
 including the initial step which is happening in JDK 23, i.e., all of the
 sun.misc unsafe memory-access methods are now marked as deprecated for
 removal. This will cause, in JDK 23, compile-time deprecation warnings for
 code that refers to these methods, alerting library developers to their
 forthcoming removal. A new command-line option also enables application
 developers and users to receive runtime warnings when those methods are
 used.

 Developers relying on those sun.misc.Unsafe APIs for access memory are
 strongly encouraged to start, if they haven't done so yet, the migration
 from the sun.misc.Unsafe APIs to supported replacements. For more details,
 make sure to read JEP 471 (Deprecate the Memory-Access Methods in
 sun.misc.Unsafe for Removal).

 [3]
 https://mail.openjdk.org/pipermail/quality-discuss/2024-January/001132.html
 [4] https://openjdk.org/jeps/471

 ## Heads-Up - JDK 23: Changes Default Annotation Processing Policy

 Annotation processing is a compile-time feature, where javac scans the
 to-be-compiled source files for annotations and then the class path for
 matching annotation processors, so they can generate source code. Up to JDK
 22, this feature is enabled by default, which may have been reasonable when
 it was introduced in JDK 6 circa 2006, but from a current perspective, in
 the interest of making build output more robust against annotation
 processors being placed on the class path unintentionally, this is much
 less reasonable. Hence, starting with JDK 23, javac requires an additional
 command-line option to enable annotation processing.

 ### New `-proc` Value
 To that end, the pre-existing option `-proc:$policy` was extended, where
 `$policy` can now have the following values:
 - `none`: compilation _without_ annotation processing, this policy exists
 since JDK 6
 - `only`: annotation processing _without_ compilation, this policy exists
 since JDK 6
 - `full`: annotation processing followed by compilation, this policy is
 the default in JDK ≤22 but the value itself is new (see next section for
 versions that support it)

 Up to and including JDK 22, code bases that require annotation processing
 before compilation could rely on javac's default behavior to process
 annotations but that is no longer the case. Starting with JDK 23, at least
 one annotation-processing command line option needs to be present. If
 neither `-processor`, `--processor-path`, now `--processor-module-path` is
 used, `-proc:only` or `-proc:full` has to be provided. In other words,
 absent other command line options, `-proc:none` is the default on JDK 23.

 ### Migration to `-proc:full`

 Several measures were undertaken to help projects prepare for the switch
 to `-proc:full`:
 - As of the April 2024 JDK security updates, support for `-proc:full` has
 been backported to 17u (17.0.11) and 11u (11.0.23) for both Oracle JDK and
 OpenJDK distributions. Additionally, Oracle's 8u release (8u411) also
 supports `-proc:full`.
 - Starting in JDK 21, javac prints an informative message if implicit
 usage of annotation processing under the default policy is detected.

 With `-proc:full` backported, it is possible to configure a build that
 will work the same before and after the change in javac's default policy.

 Additional details can be found in the original proposal [5].

 [5] https://mail.openjdk.org/pipermail/jdk-dev/2024-May/009028.html

 ## Heads-up - Loom: New EA builds with improved Java monitors
 implementation to work better with virtual threads

 Project Loom published new early-access builds [6]. These builds have an
 improved object monitor implementation that should prevent virtual threads
 from pinning their carrier thread in the following situations:
 - when blocking on entering a synchronized method/statement because the
 object's associated monitor is held by another thread,
 - when parking (e.g. when doing socket I/O) while in a synchronized method,
 - when calling `Object.wait` while in a synchronized method.
 The changes for `Object.wait`/timed-`wait` is the main change since the
 previous Loom EA build.

 The Loom team is looking for help to test the changes, i.e., trying out
 these builds with code that is known to use virtual threads and with
 libraries that are "very synchronized". The primary goal is to gauge both
 reliability and performance. Right now, the focus is on being functional
 and reliable. Please note that the performance for some cases isn't yet
 fully on par with blocking on j.u.concurrent locks and condition objects.

 As before, JFR events can be used to identify remaining cases of pinning,
 parking or blocking in a class initializer for example. The system property
 `jdk.tracePinnedThreads`, which used to print stack traces when threads are
 pinned, no longer outputs anything.

 Please send feedback via email to the Loom mailing list [7] (subscription
 required).

 [6] https://jdk.java.net/loom/
 [7] http://mail.openjdk.org/mailman/listinfo/loom-dev

 ## JDK 23 Early-Access Builds

 JDK 23 early-access builds 26 are now available [8] with the Release Notes
 here [9] and the javadocs here[10]. Those builds are provided under the GNU
 GPL v2, with the Classpath Exception.

 ### JEPs integrated into JDK 23:
 - JEP 455: Primitive Types in Patterns, instanceof, and switch (Preview)
 - JEP 466: Class-File API (2nd Preview)
 - JEP 467: Markdown Documentation Comments
 - JEP 469: Vector API (8th Incubator)
 - JEP 471: Deprecate the Memory-Access Methods in sun.misc.Unsafe for
 Removal
 - JEP 473: Stream Gatherers (2nd Preview)
 - JEP 474: ZGC: Generational Mode by Default
 - JEP 476: Module Import Declarations (Preview)
 - JEP 477: Implicitly Declared Classes and Instance Main Methods (3rd
 Preview)
 - JEP 480: Structured Concurrency (3rd Preview)
 - JEP 481: Scoped Values (3rd Preview)
 - JEP 482: Flexible Constructor Bodies (2nd Preview)

 ### Changes in recent JDK 23 builds that may be of interest:
 - JDK-8331670: Deprecate the Memory-Access Methods in sun.misc.Unsafe for
 Removal
 - JDK-8051959: Add thread and timestamp options to java.security.debug
 system property
 - JDK-8321428: Deprecate for removal the package java.beans.beancontext
 - JDK-8319990: Update CLDR to Version 45.0
 - JDK-8331975: Enable case-insensitive check in ccache and keytab entry
 lookup
 - JDK-8328083: degrade virtual thread support for GetObjectMonitorUsage
 - JDK-8326666: Remove the Java Management Extension (JMX) Subject
 Delegation feature
 - JDK-8295111: dpkg appears to have problems resolving symbolically linked
 native libraries
 - JDK-8330077: Allow max number of events to be buffered to be
 configurable to avoid OVERFLOW_EVENT
 - JDK-8332476: j.u.r.RandomGeneratorFactor.create(long|byte[]) should
 throw rather than silently fallback to no-arg create()
 - JDK-8329113: Deprecate -XX:+UseNotificationThread
 - JDK-8331202: Support for Duration until another Instant
 - JDK-8316138: Add GlobalSign 2 TLS root certificates
 - JDK-8330276: Console methods with explicit Locale
 - JDK-8330005: RandomGeneratorFactory.getDefault() throws exception when
 the runtime image only has java.base module
 - JDK-6968351: httpserver clashes with delayed TCP ACKs for low
 Content-Length
 - JDK-8331021: Deprecate and then obsolete the DontYieldALot flag
 - JDK-8330607: Deprecate -XX:+UseEmptySlotsInSupers
 - JDK-8320522: Remove code related to `RegisterFinalizersAtInit`
 - JDK-8329636: Deprecate -XX:+PreserveAllAnnotations
 - JDK-8322234: Remove obsolete desktop integration from Linux installers
 - JDK-8328649: Disallow enclosing instances for local classes in
 constructor prologues
 - JDK-8330734: JFR: Re-engineer mirror class mechanism
 - JDK-8300148: Consider using a StoreStore barrier instead of Release
 barrier on ctor exit
 - JDK-8329997: Add provisions for checking memory segment alignment
 constraints
 - JDK-8305457: Implement java.io.IO
 - JDK-8321314: Reinstate disabling the compiler's default active
 annotation processing
 - JDK-6942632: Hotspot should be able to use more than 64 logical
 processors on Windows
 - JDK-8332614: Type-checked ConstantPool.entryByIndex and
 ClassReader.readEntryOrNull
 - JDK-8206447: InflaterInputStream.skip receives long but it's limited to
 Integer.MAX_VALUE

 Note: A more exhaustive list of changes can be found here [11].

 [8] https://jdk.java.net/23/
 [9] https://jdk.java.net/23/release-notes
 [10] https://download.java.net/java/early_access/jdk23/docs/api/
 [11] https://github.com/openjdk/jdk/compare/jdk-23+17...jdk-23+26

 ## New Jextract Early-Access Builds

 New Jextract early-access builds have been made available [12]. These
 builds are based on JDK 22 and bring multiple enhancements. For additional
 details, make sure to check [13]. Moreover, a new jextract guide [14] has
 been published.

 [12] https://jdk.java.net/jextract/
 [13] https://mail.openjdk.org/pipermail/jextract-dev/2024-May/001699.html
 [14] https://github.com/openjdk/jextract/blob/master/doc/GUIDE.md

 ## JavaFX Early-Access Builds

 These are early access builds of the JavaFX 23 Runtime built from
 openjdk/jfx [15]. These builds enable JavaFX application developers to
 build and test their applications with JavaFX 23 on JDK 23. Although these
 builds are designed to work with JDK 23EA, they are also known to work with
 JDK 21 and later versions.

 The latest early access builds of JavaFX 23 are available here [16], under
 the GNU General Public License, version 2, with the Classpath Exception.
 JavaFX 23 API Javadocs [17] are also available.

 [15] https://github.com/openjdk/jfx
 [16] https://jdk.java.net/javafx23/
 [17]
 https://download.java.net/java/early_access/javafx23/docs/api/overview-su...

 ## Topics of Interest

 - All Java 23 Features - Inside Java Newscast
 https://inside.java/2024/06/06/newscast-70/

 - Module Imports in Java 23 - Inside Java Newscast
 https://inside.java/2024/05/16/newscast-69/

 - Java 23: JavaDoc Hits the Markdown on Comments - Inside Java Newscast
 https://inside.java/2024/05/01/newscast-68/

 - Java 23: Restoring the Balance with Primitive Patterns - Inside Java
 Newscast
 https://inside.java/2024/04/04/newscast-66/

 - Java in 2024 - Constant evolution, delivered.
 https://inside.java/2024/06/01/java-in-2024-keynote/

 - Introduction to JDK Mission Control
 https://inside.java/2024/05/18/jmc-intro/

 - What's New in JMC 9? - Sip of Java
 https://inside.java/2024/04/21/sip096/

 - Programmer's Guide to JDK Flight Recorder
 https://inside.java/2024/04/12/programmer-guide-to-jfr/

 - A Decade of JDK Updates in OpenJDK
 https://inside.java/2024/04/09/a-decade-of-jdk-updates/

 - Data-Oriented Programming - Version 1.1
 https://inside.java/2024/05/23/dop-v1-1-introduction/

 ~

 As usual, let us know if you find any issues while testing your project(s)
 with the latest JDK early-access builds.

 Thank you!

 --David
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Re: JDK 23 Feature Freeze / New Loom EA builds