JDK 25 LTS: Explosive Performance, Extreme Productivity, and End of Repetitive Code
Hello, developers and Java enthusiasts!
Java 25 has arrived as a Long-Term Support (LTS) version, consolidating the modernization path that the platform has taken. This update is not just a technical upgrade, but a strategic investment that translates directly into cleaner code, better performance, and a significant reduction in operational costs.
Oracle has confirmed that JDK 25 will have extended support for at least eight years, providing long-term stability for enterprise planning.
Below, we explore the key improvements that every developer and technical leader should know about.
Performance Improvements: Less Latency, More Savings
The optimizations in Java 25's runtime deliver notable gains even without modifying a single line of code.
Performance Comparison: JDK 21 vs. JDK 25 and the Leap from Java 8
Standardized benchmarks (like SPECjbb2015) show a significant boost in efficiency:
| Performance Metric | Gain when migrating to JDK 25 | Implication |
|---|---|---|
| Critical Latency (Critical JOPS - Java Operations) | Approximately 10% less | More consistent and predictable performance. |
| Maximum Performance (Max JOPS - Java Operations) | Approximately 5% increase | Greater processing capacity (throughput). |
| Cloud Cost Savings | Typically 20-30% reduction | Less need for CPU and memory resources. |
If you're still using Java 8, migrating to JDK 25 represents a performance increase of over 100% in latency. In terms of cloud infrastructure, this can mean paying a third less for resources.
Key Performance Features
Compact Object Headers (JEP 519)
This feature, now stable, reduces the size of the object headers in the HotSpot virtual machine from 96/128 bits to just 64 bits on 64-bit architectures. This directly impacts memory:
- Smaller Memory Footprint (Heap): Reductions of up to 22% in heap usage and a 20% reduction in small object sizes have been observed.
- Better Cache Efficiency: With smaller objects, more fit in the CPU's L1, L2, and L3 caches, resulting in faster execution.
AOT Method Profiling (JEP 515)
Improves the startup and "warm-up" time of applications. The HotSpot JVM can now use method execution profiles from previous runs, allowing the JIT (Just-In-Time) compiler to generate optimal native code instantly at startup, instead of waiting to collect data in real time.
Java Flight Recorder (JFR - Java Flight Recorder) Improvements
JDK 25 introduces significant improvements to JFR:
- CPU Time Profiling: More accurate capture of CPU profiling information on Linux
- Cooperative Sampling Improvements: Better cooperative sampling
- Method Timing & Tracing: Improved method timing and traceability
Developer Productivity: Write Less, Achieve More
Java 25 introduces language features that simplify syntax and eliminate ceremonial code (boilerplate), making code more expressive, concise, and readable.
| Productivity Innovation | Description | Key Benefit |
|---|---|---|
| Minimalist Main / Compact Files (JEP 512 - JDK Enhancement Proposal 512) | Allows writing the main method without explicitly declaring a class or package. | Ideal for beginners and for writing quick scripts, bringing Java closer to modern languages. |
| Pattern Matching in Switch | Includes direct deconstruction of records in the case of the switch, and grouping of alternatives separated by commas. | More concise and declarative code. |
Anonymous Pattern _ | Allows explicitly ignoring components of a record or variables that won't be used, using the underscore _. | Avoids unused variables and documents code intent. |
| Module Import Declarations (JEP 511 - JDK Enhancement Proposal 511) | Allows succinctly importing all packages exported by a module (e.g., import module java.base;). | Simplifies imports management, reducing boilerplate. |
Additionally, the use of primitive types in patterns, instanceof, and switch (Third Preview, JEP 507) adds greater coherence and expressiveness to the language.
Concurrency and Stability: The Null-Safe Future
Java 25 continues building on Virtual Threads (introduced in JDK 21), offering tools that simplify handling highly concurrent applications.
Scoped Values (JEP 506 - JDK Enhancement Proposal 506): The Successor to ThreadLocal
Scoped Values are the modern alternative to ThreadLocal, designed specifically to work securely and efficiently with Virtual Threads.
- Immutability: Unlike
ThreadLocal, values are immutable once defined, eliminating side effects. - Limited Scope: Values only exist within their execution block (
ScopedValue.where(…).run(…)) and disappear automatically upon exit, preventing memory leaks.
While Virtual Threads don't always increase performance in database-intensive workloads due to connection pool bottlenecks, their main benefit is developer productivity, allowing elimination of reactive programming complexity and returning to the simple Thread-per-Request model.
Structured Concurrency (Fifth Preview) (JEP 505 - JDK Enhancement Proposal 505)
This API treats groups of related tasks running on different threads as a single unit of work. This facilitates error management, cancellation, and improves the observability of concurrent code.
Stability Bonus Track: JSpecify
While not directly a JEP, the adoption of JSpecify (an open standard for indicating nullability) in key frameworks like Spring Framework 7 is a big step forward. This allows tools (IDEs, static analyzers) to uniformly understand whether a value can be null, bringing us closer to the end of the dreaded NullPointerException at Runtime.
Additional Improvements in JDK 25
Compiler and Runtime Improvements
- Compiler Improvements: JIT compiler optimizations to generate more efficient code
- Runtime Improvements: JVM runtime improvements for better overall performance
- Garbage Collection Improvements: Garbage collector optimizations to reduce pauses
JDK Library Improvements
- JDK Library Enhancements: Improvements in various JDK libraries for better functionality and performance
Migration Considerations
If your organization is considering migrating to JDK 25, it's important to consider:
- LTS Support: Java 25 offers robust support, reducing the frequency of major migrations.
- End of x86 32-bit Support: JDK 25 removes support for x86 32-bit architectures, so you must ensure all your operating systems are 64-bit.
- Security Model Changes: The Security Manager has been permanently disabled and its APIs will be removed in a future version. Migration to modern security models based on module systems or container security is recommended.
Migrating to JDK 25 now not only improves your application's performance, but also prepares your code for the AI and high concurrency era with a more robust, secure, and pleasant-to-use platform.
Metaphor to Understand Performance Improvements
Imagine your previous Java application was like a traditional library: each book (object) had a huge catalog card (96/128-bit object header) that took up a lot of space on the shelves (memory). With JDK 25's Compact Object Headers, it's as if you've digitized all those cards, reducing them to compact QR codes (64 bits). Now you can store many more books in the same space, find them faster, and move through the library with greater agility.
Conclusion
JDK 25 LTS represents a significant leap in Java's evolution, combining exceptional performance improvements with features that increase developer productivity. Memory optimizations, faster startup, and simplified syntax make this version an essential upgrade for organizations looking to reduce operational costs while improving code quality.
For developers, these new features offer a perfect opportunity to write cleaner, safer, and more efficient code, preparing for the challenges of modern applications in the era of AI and massive concurrency.
The future of Java is here, and it's faster, more productive, and more exciting than ever.