Taking project Loom for a spin Java and Scala examples Medium

Critically, it has very minimal impact on your server’s
performance, with most of the profiling work done separately – so
it needs no server changes, agents or separate services. Project Loom’s compatibility with existing Java ecosystem components is a significant advantage. It allows you to gradually adopt fibers where they provide the most value in your application while preserving your investment in existing code and libraries.

These two were marginally changed from their first appearance in Java 19 few months back, hence the content below is mostly the same as my last years Java 19 overview. Meaning if you are fully familiar with stuff introduced in 19 you’ll not see anything new in the coming paragraphs. Scoped values feature was directly inspired by the Lisp dialects that provide support for dynamically scoped variables, hence its syntax might be a bit different than many will expect in “traditional” Java code. Regarding how to setup a Virtual Thread (comparing with Platform threads), these are other important considerations. QCon Plus is a virtual conference for senior software engineers and architects that covers the trends, best practices, and solutions leveraged by the world’s most innovative software organizations. Now let’s do a test using something more elaborate using Executor service to schedule the threads .

Guide of Virtual Threads – Lightweight threads in Java

Even from the first release of Java, the platform has allowed for written concurrent code using a straightforward model. When first introduced, Java threads allow for a platform-independent way to write concurrent code. Without Java, developers who wanted different tasks running on different threads often had to deal with platform-specific code. The structured concurrency API is also designed to preserve order in multi-threaded environments by treating multiple tasks running in individual threads as a single logical unit of work.

• Fibers are not tied to native threads, which means they are lighter in terms of resource consumption and easier to manage.
• However, Project Loom provides a powerful tool that can simplify many aspects of concurrent programming in Java and deserves consideration in your development toolkit.
• It helped me think of virtual threads as tasks, that will eventually run on a real thread⟨™) (called carrier thread) AND that need the underlying native calls to do the heavy non-blocking lifting.
• Deepu is a polyglot developer, Java Champion, and OSS aficionado.
• The last two features in our list are the first preview that arrives at the JDK 19 from the project loom.

Virtual Threads impact not only Spring Framework but all surrounding integrations, such as database drivers, messaging systems, HTTP clients, and many more. Many of these projects are aware of the need to improve their synchronized behavior to unleash the full potential of Project Loom. Other than that, any use of standard Java IO will still yield, as described in “All Your Blocking Are Belong to Us” (did I already mention that I love the well placed puns in the article?).

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Compare the below with Golang’s goroutines or Kotlin’s coroutines. If you make them default a good portion of the existing java code won’t just be able to switch to java 19, because that code is optimized for OS threads. For example, if you want to serialize one task after another, we would use an executor service backed by a single thread.

It will continue running our thread, it will continue running our continuation after a certain time passes by. In between calling the sleep function and actually being woken up, our virtual thread no longer consumes the CPU. At this point, the carrier thread is free to run another virtual thread. Technically, you can have millions of virtual threads that are sleeping without java project loom really paying that much in terms of the memory consumption. There was also this rather obscure many-to-many model, in which case you had multiple user threads, typically a smaller number of kernel threads, and the JVM was doing mapping between all of these. With that model, every single time you create a user thread in your JVM, it actually creates a kernel thread.

Project Loom – A Preview Feature Of Java 19

As a result, it prevents the expensive context switch between kernel threads. In doing so, we also defined tasks and schedulers and looked at how Fibers and ForkJoinPool could provide an alternative to Java using kernel threads. For example, consider an application thread which performs some action on the requests and then passes on the data to another thread for further processing. Here, it would be better to schedule both these threads on the same CPU. But since the scheduler is agnostic to the thread requesting the CPU, this is impossible to guarantee.

Whereas parallelism is the process of performing a task faster by using more resources such as multiple processing units. The job is broken down into multiple smaller tasks, executed simultaneously to complete it more quickly. To summarize, parallelism is about cooperating on a single task, whereas concurrency is when different tasks compete for the same resources.

current community

The benefits of switching to a virtual thread executor are marginal in terms of container overhead. At high levels of concurrency when there were more concurrent tasks than processor cores available, the virtual thread executor again showed increased performance. This was more noticeable in the tests using smaller response bodies.

Motivation behind adding native support for lightweight / virtual threads is not to deprecate or replace current traditional Java’s Thread API. But rather to introduce this powerful paradigm that will greatly (in Oracle’s words “dramatically”) reduce the effort of creating very high scale concurrent workflows in Java. Something that other languages like Go or Erlang had for years or decades. If you want to take advantage of the benefits of Virtual Threads but without refactoring your existing code using the ExecutorService , then you can use the implementation VirtualThreadPerTaskExecutor .

Massive Revamping of blocking code in JDK

Candidates include Java server software like Tomcat, Undertow, and Netty; and web frameworks like Spring and Micronaut. I expect most Java web technologies to migrate to virtual threads from thread pools. Java web technologies and trendy reactive programming libraries like RxJava and Akka could also use structured concurrency effectively.

And hence we chain with thenApply etc so that no thread is blocked on any activity, and we do more with less number of threads. Loom is more about a native concurrency abstraction, which additionally helps one write asynchronous code. Given its a VM level abstraction, rather than just code level (like what we have been doing till now with CompletableFuture etc), It lets one implement asynchronous behavior but with reduce boiler plate.

Java 17 Features: Pattern Matching for switch and Sealed Classes

The virtual threads play an important role in serving concurrent requests from users and other applications. This is far more performant than using platform threads with thread pools. Of course, these are simple use cases; both thread pools and virtual thread implementations can be further optimized for better performance, but that’s not the point of this post. Virtual threads have a very different behavior and performance profile than platform threads. So I do not expect to see the Java team retrofitting virtual threads onto existing features of Java generally.