Ismael Juma

@ijuma

Kafka, Scala, JVM, distributed systems, performance, machine learning, Haskell, @ConfluentInc.

San Francisco Bay Area, CA

Joined December 2008

515Following

5KFollowers

Ismael Juma@ijuma · Jul 13

Foreign Function and Memory API vs Unsafe inside.java/2025/06/12/ffm…

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Ismael Juma@ijuma · Jun 15

Native Image optionally allowing open world support via Crema while Leyden brings some of the benefits of Native Image to OpenJDK via AOT Code Compilation (openjdk.org/jeps/8335368).

ААlina Yurenko 🇺🇦@alina_yurenko · Jun 4

We are working on a new big project for @GraalVM — Project Crema: github.com/oracle/graal/i…. It will lift Native Image's default closed-world assumption by allowing dynamic loading and execution of classes at run time. Stay tuned for updates!

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Ismael Juma@ijuma · Jun 8

"new performance improvements in the String class alone allow constant folding of both the key lookups and the values, thus improving performance by a factor of more than 8x"

JJava@java · May 27

In JDK 25, we improved the performance of the class String in such a way that the String::hashCode function is mostly constant foldable. Learn more: social.ora.cl/6014274Ew

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Johannes Bechberger@parttimen3rd · May 20

JFR is getting a new method sampler that walks stacks at safepoints in JDK 25. Learn all about the new sampler in this week's blog post: mostlynerdless.de/blog/2025/05/2…

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Aleksey Shipilëv@shipilev · Apr 22

A taste what is already delivered and what is coming to JDKs with Project Leyden. The warmup curve for javac compile tasks clearly improve the further you go into the AOT woods.

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Ismael Juma@ijuma · Apr 18

Java 25 will have built-in HTTP/3 client support github.com/openjdk/jdk/pu…

ijuma's tweet card. Hi, Please find here a PR for the implementation of JEP 517: HTTP/3 for the HTTP Client API. The CSR can be viewed at JDK-8350588: Implement JEP 517: HTTP/3 for the HTTP Client API This JEP propose...

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Francesco Nigro@forked_franz · Apr 18

Are you curious to see how Netty 4.2 with io_uring perform with a novel integration with Virtual Threads? Check techempower.com/benchmarks/#se… :)

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Ismael Juma@ijuma · Apr 14

Scoped Values to be finalized in Java 25 openjdk.org/jeps/506

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Bernard Traversat@BTraTra · Apr 11

The super power of var-handles in the JVM for the upcoming value types world :-) cr.openjdk.org/~jrose/values/… "Java for the AI world" #java #Valhalla #ValueType

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Ismael Juma@ijuma · Apr 9

Cute edge case allowed by javac (the PR fixes it) github.com/openjdk/jdk/pu…

ijuma's tweet card. Currently javac is accepting code like: class Test { void m() { var r = (Test & Runnable) () -> System.out.println("Hello, World!"); } } according ...

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Ismael Juma@ijuma · Apr 9

Looks like the experimental tag is being removed from Compact Object Headers in Java 25 github.com/openjdk/jdk/pu…

ijuma's tweet card. As title says. Progress Change must be properly reviewed (1 review required, with at least 1 Reviewer) Change must not contain extraneous whitespace Commit message must refer to an issue Cha...

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Krzysztof Ślusarski@k_slusar · Apr 9

Yesterday Async-profiler 4.0 was released. One of the new feature is "native memory profiling". One of the use case is finding native memory leaks. More on that topic in my new article: krzysztofslusarski.github.io/2025/03/31/nat…

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Jean-Philippe Bempel @jpbempel.bsky.social@jpbempel · Apr 8

Async-Profiler v4.0 Heatmaps and Native memory profiling and VMStructs-based stack walker github.com/async-profiler…

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Jack Vanlightly@vanlightly · Apr 3

Proud to have contributed formal verification (TLA+) for three key improvements in Kafka 4.0: ✅ KIP-966: Strengthens the replication protocol. ✅ KIP-996: Introduces PreVote for more stable KRaft leadership. ✅ KIP-848: Delivers more efficient, predictable rebalancing.

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Norman Maurer@normanmaurer · Apr 3

I am excited to finally announce the release of #netty 4.2.0.Final which is in the making for quite some time! This release comes with a lot of new exciting features, including the highly anticipated #io_uring support. See netty.io/news/2025/04/0…

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Ismael Juma@ijuma · Apr 1

"This speeds up some Loom operations by almost an order of magnitude (and similarly for CompletableFuture). Further incremental improvements may be possible, but delay scheduling overhead is now unlikely to be a common performance concern." github.com/openjdk/jdk/pu…

ijuma's tweet card. (Copied from https://bugs.openjdk.org/browse/JDK-8319447) The problems addressed by this CR/PR are that ScheduledThreadPoolExecutor is both ill-suited for many (if not most) of its applications, an...

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Phoronix@phoronix · Mar 30

IO_uring Network Zero-Copy Receive Lands In Linux 6.15 phoronix.com/news/Linux-6.1…

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Ismael Juma@ijuma · Mar 22

Looks like Bazel is looking to enable compact headers when using the embedded JDK: github.com/bazelbuild/baz… cc @rkennke

ijuma's tweet card. This allows us to adopt the feature early, but limited to the embedded JDK we control. Users of the no-JDK variant of Bazel are not affected by this change, in particular they are not limited to ru...

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