Project Loom: Understand the new Java concurrency model
The new java method from project loom to start a virtual thread is .. The project focuses on easy to use lightweight concurrency for the JavaVM. Nowadays, the JavaVM provides a one java thread to one OS thread model to the programmer. While it’s actually the current Oracle implementation, it used to be that many JavaVM versions ago, threads provided to the programmer were actually green threads. Loom and Java in general are prominently devoted to building web applications. Obviously, Java is used in many other areas, and the ideas introduced by Loom may well be useful in these applications.
- Some, like CompletableFutures and Non-Blocking IO, work around the edges of things by improving the efficiency of thread usage.
- In Java 19 were introduced Virtual Threads JEP-425 as a preview feature.
- When you want to make an HTTP call or rather send any sort of data to another server, you (or rather the library maintainer in a layer far, far away) will open up a Socket.
- You can also create a ThreadFactory if you need it in some API, but this ThreadFactory just creates virtual threads.
Structured concurrency aims to simplify multi-threaded and parallel programming. It treats multiple tasks running in different threads as a single unit of work, streamlining error handling and cancellation while improving reliability and observability. This helps to avoid issues like thread leaking and cancellation delays. Being an incubator feature, this might go through further changes during stabilization.
Alternatives to fibers in Java
Now it’s easy, every time a new HTTP connection comes in, you just create a new virtual thread, as if nothing happens. This is how we were taught Java 20 years ago, then we realized it’s a poor practice. These days, it may actually be a valuable approach again.
It’s easy to see how massively increasing thread efficiency, and dramatically reducing the resource requirements for handling multiple competing needs, will result in greater throughput for servers. Better handling of requests and responses is a bottom-line win for a whole universe of existing and to-be-built Java applications. Should you just blindly install the new version of Java whenever it comes out and just switch to virtual threads? I think the answer is no, for quite a few reasons. First of all, the semantics of your application change. You no longer have this natural way of throttling because you have a limited number of threads.
Using Virtual Threads (Project Loom) with Spring WebFlux/Reactor/Reactive libraries
Get to the root cause of problems quickly, without losing context from switching between tools. Loom is an open source Java https://www.globalcloudteam.com/ web framework that uses annotations to validate user input. Structured concurrency will be an incubator feature in Java 19.
Fourth level architecture to have better understanding. For details and insights, be sure to read the articles and watch the presentations and interviews by Ron Pressler, Alan Bateman, or other members of the Project Loom team. Such a code base would be better, loom java clearer, more obvious to comprehend if explicit limiting/throttling mechanisms were utilized. If you browse through Executors class Javadoc, you will see a variety of options. The programmer chooses one to suit the needs of her particular situation.
Project loom: what makes the performance better when using virtual threads?
Here we share with you industry tips & best practices, based on our experience. Granted benchmarking in Java can’t simply be done by measuring elapsed time, because of the way Hot Spot VM works and the warm up time it needs to reach optimal levels of compilation before benchmarking. Trying to get up to speed with Java 19’s Project Loom, I watched Nicolai Parlog’s talk and read several blog posts. And debugging is indeed painful, and if one of the intermediary stages results with an exception, the control-flow goes hay-wire, resulting in further code to handle it.
To solve all the mentioned pitfalls Oracle introduces a new -lightweight- data sharing system that makes the data immutable hence it can be shared by child threads efficiently. To understand why the scoped values feature was developed one needs to have a good understanding of the Thread Local variables, with all of its strong sides and downfalls. If a village has a loom that has not been claimed by a villager, any villager who hasn’t already chosen a job site block has a chance to change their profession to shepherd. With sockets it was easy, because you could just set them to non-blocking. But with file access, there is no async IO (well, except for io_uring in new kernels). Loom is more about a native concurrency abstraction, which additionally helps one write asynchronous code.
It’s never too late or early to start something
If you suspend such a virtual thread, you do have to keep that memory that holds all these stack lines somewhere. The cost of the virtual thread will actually approach the cost of the platform thread. Because after all, you do have to store the stack trace somewhere. Most of the time it’s going to be less expensive, you will use less memory, but it doesn’t mean that you can create millions of very complex threads that are doing a lot of work. In case of Project Loom, you don’t offload your work into a separate thread pool, because whenever you’re blocked your virtual thread has very little cost. However, you will still be probably using multiple threads to handle a single request.
Before we put ourselves to sleep, we are scheduling an alarm clock. 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.
Concurrency Model of Java
Another possible solution is the use of asynchronous concurrent APIs. CompletableFuture and RxJava are quite commonly used APIs, to name a few. These APIs do not block the thread in case of a delay.
This means that the performance of the virtual threading functionality is bound to improve in the future, including compared to Kotlin’s coroutines. In any case, virtual threads will provide yet another tool for developers in the JVM ecosystem, and it will be very interesting to see how this functionality will grow and evolve in the years to come. 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.
Project Loom: Understand The New Java Concurrency Model
We no longer have to think about this low level abstraction of a thread, we can now simply create a thread every time for every time we have a business use case for that. There is no leaky abstraction of expensive threads because they are no longer expensive. As you can probably tell, it’s fairly easy to implement an actor system like Akka using virtual threads, because essentially what you do is you create a new actor, which is backed by a virtual thread. There is no extra level of complexity that arises from the fact that a large number of actors has to share a small number of threads. However, it turns out, first of all, it’s very easy with that tool to show you the actual Java threads. Rather than showing a single Java process, you see all Java threads in the output.