Web applications and Project Loom

I will not go into the API too much because it’s subject to change. You essentially say Thread.startVirtualThread, as opposed to new thread or starting a platform thread. A platform thread is your old typical user threads, that’s actually a kernel thread, but we’re talking about virtual threads here. You can create it using a builder method, whatever. This ExecutorService doesn’t actually pull threads. Typically, ExecutorService has a pool of threads that can be reused in case of new VirtualThreadExecutor, it creates a new virtual thread every time you submit a task.

• First of all, there’s this concept of a virtual thread.
• Let’s try to run 100,000 tasks using platform threads.
• In 1998, it was amazing that the Sun Java Web Server (the precursor of Tomcat) ran each request in a separate thread, and not an OS process.
• Parallel streams work great when the data structure is cheap to split into parts and the operations keep the processors busy.
• The implementation is based on an idea such as continuation and operations related to them defined as parking and unparking.
• This piece of code is quite interesting, because what it does is it calls yield function.
• To cater to that, the project Loom also aims to add lightweight stack retrieval while resuming the continuation.

All inheritable thread locals are copied to each child thread so that the child can update or remove them without affecting the parent. In Java, you cancel a thread by invoking its interrupt method. This only sets the “interrupted” flag of the thread.

“Sequenced Collections”: an upcoming feature of Java 21 to handle a sequence of elements in a better way.

After all, if one takes 6 seconds and the other 3 seconds, you still come in under the finish line. To get the timeout of the second task, you’d have to measure the duration of the first task and subtract that from the overall timeout. Then try using OS threads—change to Executors.newCachedThreadPool() or Executors.newFixedThreadPool(NTASKS).

The method runs tasks concurrently, until one completes successfully, and then cancels all others. Contrast that with CompletableFuture.anyOf, which lets all tasks run to completion, even though all but the first result will be ignored. Suppose you have to accomplish two sequential tasks with an overall timeout of 10 seconds. You don’t want to give each of the tasks a timeout of 5 seconds.

OpenJDK Project Loom

Even more interestingly, from the kernel point of view, there is no such thing as a thread versus process. This is just a basic unit of scheduling in the operating system. The only difference between them is just a single flag, when you’re creating a thread rather than a process.

CompletableFuture and RxJava are quite commonly used APIs, to name a few. These APIs do not block the thread in case of a delay. Instead, it gives the application a concurrency construct over the Java threads to manage their work. One downside of this solution is that these APIs are complex, and their integration with legacy APIs is also a pretty complex process. If the resource that fits was working on responses, we could allocate the thread to another carrier operating system thread. It could be the same carrier thread or a different one.

Future of Project Loom

Virtual threads could be a no-brainer replacement for all use cases where you use thread pools today. This will increase performance and scalability in most cases based on the benchmarks out there. Structured concurrency can help simplify the multi-threading or parallel processing use cases and make them less fragile and more maintainable. These and other investments are supporting more than 165,000 jobs in New York’s clean energy sector in 2021 and over 3,000 percent growth in the distributed solar sector since 2011. To reduce greenhouse gas emissions and improve air quality, New York also adopted zero-emission vehicle regulations, including requiring all new passenger cars and light-duty trucks sold in the State be zero emission by 2035.

The solution is to introduce some kind of virtual threading, where the Java thread is abstracted from the underlying OS thread, and the JVM can more effectively manage the relationship between the two. That is what project Loom sets out to do, by introducing a new virtual thread class called a fiber. There’s also a different algorithm or a different initiative coming as part of Project Loom called structured concurrency. Essentially, it allows us to create an ExecutorService that waits for all tasks that were submitted to it in a try with resources block.

Executor services

Project Loom reimagines threads by giving us an essentially unlimited number of them. Since we don’t have to pool threads, each concurrent task can have its own virtual thread. And since blocking is cheap, we can express our logic with plain control flow—branches, loops, method calls, exceptions. There is no need for cumbersome callbacks or async flavors. Netty is used to create high-performance protocols servers and clients to allow for optimal resource utilization.

It’s due to the parked virtual threads being garbage collected, and the JVM is able to create more virtual threads and assign them to the underlying platform thread. First, let’s see how many platform threads vs. virtual threads we can create on a machine. My machine is Intel Core i H with 8 cores, 16 threads, and 64GB RAM running Fedora 36. Virtual threads are lightweight threads that are not tied to OS threads but are managed by the JVM. They are suitable for thread-per-request programming styles without having the limitations of OS threads.

Project loom: what makes the performance better when using virtual threads?

The main technical mission in implementing continuations — and indeed, of this entire project — is adding to HotSpot the ability to capture, store and resume callstacks not as part of kernel threads. Should you just blindly install the new version of Java whenever it comes out and just switch to virtual threads? First of all, the semantics of your application change.

To work around this, you have to use shared thread pools or asynchronous concurrency, both of which have their drawbacks. Thread pools have many limitations, like thread leaking, deadlocks, resource thrashing, etc. Asynchronous concurrency means you must adapt to a more complex programming style and handle data races carefully. There are java virtual threads also chances for memory leaks, thread locking, etc. Additionally, these projects also align with available federal tax credits, enabling future savings to New York’s ratepayers. Today’s awards also mark the commencement of contract negotiations with the awarded parties, and the awards are conditional on successful contract execution.

Massive Revamping of blocking code in JDK

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. Governor Kathy Hochul today announced the largest state investment in renewable energy in United States history, demonstrating New York’s leadership in advancing the clean energy transition. Following these awards, New York will now have enough operating, contracted, and under development renewable energy projects to supply 79 percent of the state’s 2030 electricity needs with renewable energy. Depending on the web application, these improvements may be achievable with no changes to the web application code. The primary driver for the performance difference between Tomcat’s standard thread pool and a virtual thread based executor is contention adding and removing tasks from the thread pool’s queue.