Welcome to the latest OpenJDK Quality Outreach update!
The first JDK 22 Release Candidates builds are now available [1]. At this
stage, only P1 issues will still be evaluated. And with the JDK 22 General
Availability set for March 19th, it is now time to fully focus on JDK 23. At
the time of writing, one JEP has already been integrated in JDK 23, i.e., JEP
455: 'Primitive Types in Patterns, instanceof, and switch (Preview)' [2]. But
new JEP candidates [3][4] have recently been announced, so things should evolve
rapidly.
I'd like to thank those of you who have already provided feedback on the JDK 22
EA builds. Feedback is always extremely useful, even more, when it comes early
in the development cycle. Another area where we need your help is Loom. So,
please make sure to check the heads-up below that discusses the so-called
Virtual Threads "pinning" issue.
[1] https://openjdk.org/projects/jdk/22/
[2] https://openjdk.org/jeps/455
[3] https://openjdk.org/jeps/465
[4] https://openjdk.org/jeps/466
## Heads-up: Virtual Threads “Pinning” Issue
Virtual threads became a permanent feature in JDK 21. This feature has been
extremely well received by the Java ecosystem but there are still a few pain
points. Much has been written about the so-called "pinning" issue that arises
with synchronized methods or synchronized statements. The two most common cases
are (a) a virtual thread parks (ex. doing socket I/O) while in a synchronized
method, and (b) a virtual thread blocks entering a synchronized method because
the object's associated monitor is held by another thread. In both cases, the
underlying carrier/native thread is not "released" to do other work.
Performance and scalability may suffer and in some cases, starvation and
deadlock might happen. This recent "Virtual Threads Next Steps" video [5]
explains in more details the why's and discusses some potential solutions.
New Loom early-access builds haven been recently published [6]. Those Loom EA
builds have changes to the object monitor implementation that do not pin for
these two common cases. The Loom team needs your help to test these updated
object monitors with code that you know is using virtual threads and with
libraries that are heavily synchronized. The goal is to gauge both reliability
and performance.
The simplest way to report an issue or feedback is to use the Loom mailing list
[7]. For the VM savvy, testing with both `-XX:LockingMode=1` (current default)
and `-XX:LockingMode=2` would be extremely helpful as that would exercise the
two locking modes currently implemented by the HotSpot VM.
[5] https://inside.java/2024/02/17/virtual-threads-next-steps/
[6] https://jdk.java.net/loom/
[7] https://mail.openjdk.org/pipermail/loom-dev/
## JDK 22 Release Candidates
The JDK 22 Release Candidate builds (builds 36) are available [8] and are
provided under the GNU General Public License v2, with the Classpath Exception.
The Release Notes are available here [9], and the javadocs here [10].
[8] https://jdk.java.net/22/
[9] https://jdk.java.net/22/release-notes
[10] https://download.java.net/java/early_access/jdk22/docs/api/
## JDK 23 Early-Access Builds
The JDK 23 Early-Access builds 10 are available [11], and are provided under
the GNU General Public License v2, with the Classpath Exception. The Release
Notes are available here [12].
### Changes in recent JDK 23 builds that may be of interest:
- JDK-8324287: Record total and free swap space in JFR
- JDK-8275338: Add JFR events for notable serialization situations
- JDK-8324665: Loose matching of space separators in the lenient date/time
parsing mode
- JDK-8324066: "clhsdb jstack" should not by default scan for j.u.c locks
because it can be very slow
- JDK-8323699: MessageFormat.toPattern() generates non-equivalent MessageFormat
pattern
- JDK-8325221: Obsolete TLABStats
- JDK-8322535: Change default AArch64 SpinPause instruction
- JDK-8323746: Add PathElement hashCode and equals
- JDK-8325570: Update to Graphviz 9.0.0
- JDK-8303866: Allow ZipInputStream.readEnd to parse small Zip64 ZIP files
- JDK-8320458: Improve structural navigation in API documentation
- JDK-8324068: Improve references to tags in the Doc Comment Spec
- JDK-8322366: Add IEEE rounding mode corruption check to JNI checks
- JDK-8321545: Override toString() for Format subclasses
- JDK-8324301: Obsolete MaxGCMinorPauseMillis
- JDK-8324632: Update Zlib Data Compression Library to Version 1.3.1
- JDK-8324771: Obsolete RAMFraction related flags
- JDK-8323645: Remove unused internal sun.net.www.protocol.jar.URLJarFileCa…
- JDK-8325150: (tz) Update Timezone Data to 2024a
- JDK-8324571: JDK 23 L10n resource files update
Note: Complete list of changes can be found here [13].
[11] https://jdk.java.net/23/
[12] https://jdk.java.net/23/release-notes
[13] https://github.com/openjdk/jdk/compare/jdk-23+6...jdk-23+10
## JavaFX Early-Access Builds:
These are early access builds of the JavaFX 22 & 23 Runtime bui
