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IBM Semeru Runtimes is an OpenJDK-based Java distribution designed to run all Java workloads seamlessly — just like any other Java runtime you may be familiar with. In other words, Semeru Runtimes is “commodity Java,” meaning it fully adheres to Java SE standards and supports all major frameworks and tools. This ensures smooth application execution without compatibility concerns.
This makes Semeru Runtimes an ideal choice for modernizing legacy Java applications while leveraging the scalability and efficiency of cloud-native platforms like Kubernetes. Legacy Java applications remain the backbone of many enterprises — from banking systems to retail backends. While these applications continue to function, they often struggle to meet the demands of today’s cloud-native, microservices-driven environments.
If you’re dealing with challenges like slow startup times, high memory consumption, or inefficient container performance, it’s time to rethink your deployment strategy. IBM Semeru Runtimes + Kubernetes provide the perfect combination to seamlessly transition legacy Java applications into the modern cloud era.
Legacy Java apps were often:
Modernizing them for cloud-native infrastructure introduces challenges:
To fix this, we need a JVM that’s designed for the cloud, and a platform that supports dynamic, scalable deployments.
IBM Semeru Runtimes is an OpenJDK distribution powered by Eclipse OpenJ9 — a JVM optimized for:
Unlike traditional JVMs, OpenJ9 was built from the ground up to be efficient in modern deployment models like Docker and Kubernetes.
💡 Developer Tip: Before diving into containerization or Kubernetes, you can easily try out IBM Semeru Runtimes locally on your machine to test your legacy app. Here’s how you can do it with SDKMAN! — a convenient Java version manager.
# Install SDKMANcurl -s "https://get.sdkman.io" | bashsource "$HOME/.sdkman/bin/sdkman-init.sh"
# Install IBM Semeru JDK 21sdk install java 21.0.6-sem
# Verify installationjava -version
Now that you’ve tried Semeru locally, let’s explore how Semeru can specifically help modernize your legacy applications.
IBM Semeru reduces startup times, enabling faster application initialization and better responsiveness in scaling scenarios — ideal for microservices and serverless environments..
OpenJ9 can use 30–50% less memory than traditional JVM — freeing up RAM and reducing cloud costs.
Semeru allows you to run JIT compilation as a remote service — saving memory on the container running the app.
Semeru respects cgroup limits, meaning your app won’t over-allocate resources in a Kubernetes pod.
Semeru’s Shared Class Cache (SCC) stores frequently used Java class metadata in memory, enhancing class loading efficiency and reducing overall execution overhead.
Note: For consistent benefits in containerized environments, it’s best to build the cache during the container image creation rather than at runtime.
Kubernetes offers:
Combined with Semeru, your legacy Java app becomes:
Here’s a simplified path:
Wrap your legacy WAR/JAR with a Dockerfile:
FROM ibm-semeru-runtimes:open-17-jdk-focal # or another semeru jdk versionCOPY target/myapp.jar /app/myapp.jarWORKDIR /appCMD ["java", "-jar", "myapp.jar"]
Create Kubernetes manifests (deployment + service), or use Helm for production-ready packaging.
Use Prometheus, Grafana, or OpenJ9 tools to observe memory, GC, and startup behavior. Optimize your application with Semeru benefits.
A large financial services company migrated a monolithic Java 8 application to:
Results:
Modernizing Java apps isn’t just about breaking monoliths. It’s also about choosing the right runtime that aligns with modern infrastructure.
IBM Semeru JDK + Kubernetes offers a powerful foundation to:
If you’re ready to breathe new life into legacy Java systems, start with Semeru and scale with Kubernetes.
Because modern problems need modern runtimes.
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