Talk

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John, a software engineer and trainer for Atomic Jar, introduces the last session of the day focused on the latest Java versions 19 and 20. He encourages the audience to switch to the latest Java version for better performance and other benefits. He also introduces a new feature called Project Loom which is a new concurrency structure or idiom that allows for more threads per request. There have been no new language syntax changes, however, there are new features such as pattern matching and native call improvements. To enable these features, you must have the proper Java version installed and use the enable preview flag. This change has sparked debate as to whether it is the biggest change since Lambda was introduced in Java 8. Virtual threads are the new form of threads in concurrency, replacing the older \"fiber\" model. They are designed to be easier to start, faster, and have less overhead than traditional threads. They cannot be changed in terms of priority or demon status, and are meant to be used in places where a thread is waiting for an operation such as data from storage or a network call. In Java 19 and 20 there is an option to opt out of thread locals, however this will not be available in Java 21. To use virtual threads, developers must go into their source code and tell the program to use virtual threads instead of new threads. This can be done with the \"start virtual thread\" command, or by using an executor. A factory can also be created for virtual threads if needed. To test virtual threads, developers can use a dummy example of a microservice with an HTTP server and Toxic Proxy to create a latency of half a second. This will show if any core colors of the HTTP client become blocked and therefore pinned. Test containers can also be used to help with this testing process. To detect if virtual threads are pinned, one can use JDK Trace or Java Flight Recorder events. Java 16 now offers Structured Concurrency and a Record data carrier as a standard. Java 20 has introduced pattern matching for switch and record patterns which is more null friendly and allows for combining null and default. It also handles objects, not just primitives, and does not allow for fall through. It works with both switch expression and switch instructions, as well as records and nesting. Native code can be tedious, unsafe, limited and slow, but Java 20 has introduced new native features to improve speed, safety and usability. The Java Foreign Function and Memory API has been around for at least six releases and provides a way to access native memory. The talk provided an overview of the latest Java versions 19 and 20 and the new features they offer. It offered suggestions on how to test virtual threads and introduced changes and improvements to the language syntax. It concluded with an invitation to participate in an anonymous survey and follow the speaker on social media for more IT tips and pool life advice.

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