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As usual before a Java release, I'm listing all the new performance features in the upcoming release, this time for Java 22 (I have done this every 6 months prior to each new release, you can track back to the previous February and August newsletters if you want to see what's new performance-wise in any particular release). Each time I give the new features, the performance benefits from each feature, and how to use the feature.

Java 22 has one significant new feature, the Foreign Function and Memory API. This is finally released after more than 10 years since first being started as project panama. It's perhaps a strength of the JDK 6 monthly release cadence that a project can continue for 10 years, and get steadily improved from multiple rounds of feedback. The corresponding weakness is that these larger projects seem to take much longer than expected to deliver - panama taking more than 10 years, virtual threads took more than 6 years and even then it's not pre-emptive and has noticeable limitations.

Now on to the details of those Java 22 changes, including the options you have available to use them. And of course the tips from this month's articles, as ever are extracted into this month's tips page.

A note from this newsletter's sponsor

News

Java performance tuning related news - Java 22 performance changes

• Foreign Function & Memory API Useful for detailed memory management including off heap, and faster than JNI calling non-JVM functions
• Java's Virtual Threads - Next Steps - includes details about improved throughput for network IO operations on virtual threads in Java 22
• JDK-8305753 JIT compilation is now supprted for -Xshare:dump when -Xmixed is also specified
• JDK-8316735 Hotspot hs_err files now print the lock stack when -XX:LockingMode=2 is enabled
• JDK-8306441 Application pause time during heap dumps has been significantly reduced
• JDK-8314243 A new -XX:UserThreadWaitAttemptsAtExit=N specified how long the JVM waits for user threads to stop executing native code; N specifies the number of 10ms waits up to a maximum of 10 seconds, defaulting to 300ms
• JDK-8211238 A new JFR event has been added, jdk.DeprecatedInvocation
• JDK-8319551 There is increased startup time when Using -XX:StartFlightRecording - this is expected to be decreased again in a future JDK version
• JDK-8288899 New ForkJoin* methods invokeAllUninterruptibly, adaptInterruptible
• JDK-8308593 TCP_KEEP* extended socket options now supported on Windows
• GC improvement: JEP423 Region pinning for G1 means better GC performance when JNI code executes
• GC improvement: JDK-8321013 Better Parallel GC throughput with large object arrays
• GC improvement: JDK-8310031 Precise Parallel GC scanning of large object arrays for young collection roots
• GC improvement: JDK-8319373 Better Serial GC throughput with scarce dirty cards
• GC improvement: JDK-8315503 Better G1 GC code root scan phase during garbage collection
• GC improvement: JDK-8140326 Faster G1 GC collection of Evacuation Failed regions
• GC improvement: JDK-8314573 More deterministic G1 GC heap resize at remark
• JEP464 Scoped Values (Second Preview) More efficient than thread-local variables, especially with large numbers of virtual threads
• JEP462 Structured Concurrency (Second Preview). Simplify concurrent programming by grouping related tasks running in different threads
• JEP460: Vector API (Seventh Incubator). Vector computations that reliably compile at runtime to optimal vector hardware instructions. Useful for ML, image processing, scientific processing, massive financial calculations, etc

Tools

Java performance tuning related tools

• Foreign Function & Memory API examples
• Foreign Function & Memory API source code examples
• All the performance changes in the JVM since Java/JDK/JVM 10

Articles

• Bare metal Java (Jaroslaw Palka/GeeCON)
• The Panama Dojo: Black Belt Programming with Java 21 and the FFM API By Per Minborg (Per Minborg/Devoxx)
• Project Panama: Interconnecting the Java Virtual Machine and Native Code (Paul Sandoz/Oracle)

Jack Shirazi

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