OpenJDK 17 - The Java Version Everyone's Actually Using

Java 17 came out in September 2021, and it's finally the version that got enterprises to stop clinging to Java 8 like it's a security blanket. New Relic's 2024 report shows about a third of production apps now run on Java 17, way up from single digits last year. Meanwhile, Azul's 2025 survey shows closer to 60% usage, making it the dominant choice for new enterprise projects.

The JetBrains Developer Survey 2024 confirms this trend, with Stack Overflow's 2024 Developer Survey showing Java 17 as the most commonly used Java version among professional developers. GitHub's State of the Octoverse reports that Java 17 is now the default for new repositories, overtaking Java 8 for the first time since 2014. Multiple industry reports and Snyk's JVM ecosystem report highlight this massive shift toward LTS adoption, with Java 17 becoming the clear enterprise choice.

The Oracle Licensing Nightmare That Drove Adoption

Here's what happened: Oracle decided that Oracle JDK 17 updates after version 17.0.12 cost money. Starting with version 17.0.13 in October 2024, you need a paid license. Suddenly, everyone's looking at OpenJDK builds going "wait, this is exactly the same code but free?"

Oracle pulled their usual move: Oracle JDK 17 updates after version 17.0.12 now cost money. Same exact code, now with a price tag because fuck you, that's why. The Oracle Binary Code License Agreement essentially says "free for development, pay us for production." Meanwhile, enterprise Java licensing costs can run $25-50 per named user annually, plus processor-based fees that make your CFO weep.

The GPL v2 with Classpath Exception means you can ship commercial products without worrying about some lawyer showing up with a bill. It's the same license Linux uses, so if you're not worried about that, you're fine here. InfoWorld's Java licensing coverage and Java licensing guides explain why most companies are ditching Oracle JDK entirely.

Performance: Actually Worth The Migration Effort

OptaPlanner's benchmarks show Java 17 is roughly 8% faster than Java 11 with G1GC. That doesn't sound like much until you realize that's potentially less AWS bill every month. For CPU-heavy stuff, it matters. For typical CRUD apps that spend all their time waiting on databases, you probably won't notice.

The Renaissance Benchmark Suite shows similar improvements across multiple workload types. JetBrains IDE improvements show compilation times were about 15-20% faster with Java 17. Even Netflix's engineering blog reports noticeable improvements in their microservices architecture after migration. VeryGoodSecurity's migration study documents real production gains, while Azul's performance tests show even bigger improvements with their optimized builds.

Performance improvements in Java 17 are measurable: OptaPlanner documented 8% performance gains over Java 11, with Renaissance benchmarks showing similar improvements across different workloads.

The Features That Actually Matter

Java 17 has some nice language improvements, but let's be honest about what you'll actually use:

• Records: Finally, immutable data classes that don't require 50 lines of boilerplate
• Text blocks: Multi-line strings without the + nightmare
• Pattern matching for switch: Still in preview, but makes complex conditionals less awful
• Strong encapsulation: Breaks your reflection-heavy code, but makes everything more secure

The sealed classes are cool in theory but most teams haven't figured out where to use them yet. The Vector API is still incubator status - don't bet production code on it. InfoQ's Java coverage and Baeldung's comprehensive overview provide practical examples of these features in action.

Java LTS Release Schedule: Java 17 (2021-2029), Java 21 (2023-2031), Java 25 (2025-2033) - each LTS version gets at least 8 years of support from various vendors.

What Actually Breaks During Migration

Migrating from Java 8 or 11 isn't as smooth as the marketing materials claim. Here's what will ruin your weekend:

• Your reflection-heavy frameworks (looking at you, older Spring versions) will throw IllegalAccessError
• Anything using sun.misc.Unsafe needs --add-opens flags or proper fixes
• Old versions of Maven/Gradle won't handle modules properly
• Some Jackson versions have issues with records and sealed classes

The strong encapsulation changes mean you can't access internal JDK APIs anymore. This is good for security, terrible for legacy code that does sketchy reflection magic. Oracle's migration guide and JEP 261 explain the module system changes in detail, while Spring's migration documentation shows how major frameworks adapted.

LTS Means "We Won't Break Your Stuff For 3+ Years"

Unlike the 6-month release cycle madness, LTS versions get security updates until the next LTS. Java 17 support runs until at least 2029, with vendors like Red Hat extending it to 2030+. This gives you time to migrate at your own pace instead of playing version roulette every few months.

The next LTS is Java 21 (out since September 2023) and Java 25 (coming September 2025). While Java 21 adoption is growing fast, most companies are staying on Java 17 because migration fatigue is real and Java 17 works fine for their needs.

The Real Migration Experience From Java 8/11

I've been through this migration dance three times now. Here's what actually happens when you upgrade a real production app, not some hello-world demo:

Day 1 - "This Should Be Easy"
Download Java 17, change JAVA_HOME, run tests. Half your tests explode with IllegalAccessError. Your build fails because Maven 3.6.0 from 2018 doesn't understand modules. Spring Boot 2.3 throws reflection warnings everywhere.

Days 2-3 - "Fixing The Obvious Stuff"
Update Maven to 3.8.6+, Gradle to 7.3+. Upgrade Spring Boot to 2.5+ (minimum that plays nice with Java 17). Add --add-opens java.base/java.lang=ALL-UNNAMED to your JVM args until you can properly fix the reflection issues.

Migration typically follows this pattern: Day 1 (environment setup issues), Days 2-3 (build tool updates), Week 1-2 (dependency conflicts and reflection fixes).

Week 1-2 - "The Deep Pain"
Your Jackson version doesn't handle records properly. Mockito versions before 4.6 choke on record classes. Some random utility library that hasn't been updated since 2019 uses internal APIs and needs replacing. Your Docker base images use Java 8 and need updating.

Your CI/CD pipeline breaks because the Jenkins agent runs Java 11 and can't compile Java 17 bytecode. The deployment fails at 2 AM because Maven Surefire 2.22 doesn't understand the module system and nobody thought to test the build pipeline.

JVM Architecture Changes: Java 17's strong encapsulation means internal APIs are locked down, breaking reflection-heavy code that previously worked.

Which OpenJDK Build To Actually Use

Everyone's asking "which vendor should I pick?" Here's the honest breakdown:

Amazon Corretto - Just works. If you're on AWS, use this. Free updates until 2029, no surprises. I've never had issues with it. Their performance documentation show consistent results across EC2 instances.

Eclipse Temurin - The safe community choice. Former AdoptOpenJDK that got corporate backing. Solid builds, predictable releases. If you don't know what to pick, pick this. Adoptium's quality assurance process ensures rock-solid builds.

Microsoft Build of OpenJDK - Good if you're in Azure land. Free support until 2027. Microsoft's Java team actually knows what they're doing. Azure integration guides show seamless deployment options.

Red Hat OpenJDK - Enterprise-grade if you're already paying Red Hat for RHEL. Support until 2030+. RHEL integration is bulletproof for enterprise environments.

Azul Platform Core - The performance nerds' choice. Their commercial Zing JVM is actually impressive, but the free Core builds are solid too. Azul's benchmark studies consistently show performance leadership.

Avoid Oracle JDK unless your company enjoys paying $2.50 per user per month plus server licensing fees. That's $30/user/year for the same code you get free elsewhere. WhichJDK.com and Java licensing calculators help you understand the real costs.

The \"Oh Shit\" Migration Moments

Classic Error #1: Reflection Hell

java.lang.IllegalAccessError: class X cannot access class sun.misc.Unsafe

Your app probably uses some library that does reflection magic. Fix: --add-opens java.base/sun.misc=ALL-UNNAMED as a temporary band-aid, then find a proper solution.

Classic Error #2: Module Madness

java.lang.NoClassDefFoundError: javax/xml/bind/JAXBException

Java 17 removed JAXB from the base modules. Add the dependency manually: javax.xml.bind:jaxb-api:2.3.1.

Classic Error #3: Build Tool Confusion
Maven < 3.8 doesn't handle Java 17 properly. Gradle < 7.3 will make you cry. Update your build tools first, save yourself the headache.

The migration from Java 8 usually takes 2-4 weeks if you have decent test coverage. Java 11 to 17 is more like a week. Don't listen to anyone who says "it's just a drop-in replacement" - they're lying or they've never migrated a real app.

Version Compatibility: Most Java 11 apps migrate to Java 17 with minimal changes. Java 8 migrations require more work due to module system and API changes.

Garbage Collection Improvements: G1GC performance is significantly better in Java 17, with lower pause times and better memory utilization.

What Actually Works Better in Production

Security Updates That Don't Suck
Unlike Oracle's "pay us or stay vulnerable" model, OpenJDK vendors push security fixes fast. When Log4Shell happened, Corretto and Temurin had patches within hours. The strong encapsulation changes also help - your app can't accidentally use internal APIs that become security holes later. CVE response times show OpenJDK vendors consistently beat Oracle on security patch deployment.

Container Performance That Matters
Java 17 containers start up noticeably faster and use less memory at idle. The improved random number generation means less blocking on /dev/random in containerized environments. Your Kubernetes pods will actually be ready when they say they're ready. Docker's Java guides and Kubernetes Java optimization guides show real improvements in orchestrated environments.

Container Improvements: Java 17 properly detects container memory limits and adjusts heap sizes automatically, fixing a major pain point from Java 8.

Better Observability Out of the Box
JFR (Java Flight Recorder) is actually useful now. It's free, always-on, and gives you real performance data instead of guesswork. If you're not using it, you're flying blind. Combined with tools like async-profiler, you can actually figure out why your app is slow. JFR documentation and profiling guides provide comprehensive monitoring strategies.

The bottom line: Java 17 is what you should be using in 2025. It's stable, fast, free, and supported. Oracle can keep their licensing lawyers - the rest of us moved on. Java roadmap discussions and community adoption metrics confirm this is the right long-term bet for most teams.