News
Microsoft Launches 'jaz' to Optimize Java Applications on Azure
- By John K. Waters
- June 3, 2025
Microsoft has announced the private preview of jaz, a new Java Virtual Machine (JVM) launcher tailored for cloud deployments on Azure. The tool aims to address long-standing challenges developers face when tuning JVM parameters for containerized and virtual machine environments.
According to Microsoft Principal Product Manager Bruno Borges, over 30% of Java developers deploy applications without custom JVM tuning, relying on the conservative default configurations in OpenJDK. These defaults, though safe, often underutilize cloud resources, leading to higher costs and reduced performance.
The jaz launcher is designed to provide optimized JVM defaults for cloud-native workloads, automatically adjusting settings like heap size and garbage collection to better align with the memory and CPU constraints typical of cloud environments. It builds on existing JVM technologies, including AppCDS and, eventually, Project Leyden, which aims to improve startup times and performance through static images.
"jaz helps developers achieve better performance on first deployment by detecting runtime conditions and applying sensible defaults," Borges wrote in a Microsoft blog post. The tool automatically identifies memory limits and workload types and launches the JVM with optimized flags for heap sizing, garbage collection, and diagnostic logging.
The initiative follows ongoing efforts by Microsoft, Oracle, and Google to develop dynamic heap tuning features for future OpenJDK releases. However, jaz targets developers still working with older versions like OpenJDK 8, 11, 17, and 21. Until dynamic tuning becomes more widely available, tools like jaz offer immediate benefits for developers using frameworks like Spring Boot, Quarkus, or Micronaut in container-based environments.
jaz is currently available through a private preview, with Microsoft working alongside select customers to refine the tool and collect feedback. Developers can submit their interest to participate in the program.
About the Author
John K. Waters is the editor in chief of a number of Converge360.com sites, with a focus on high-end development, AI and future tech. He's been writing about cutting-edge technologies and culture of Silicon Valley for more than two decades, and he's written more than a dozen books. He also co-scripted the documentary film Silicon Valley: A 100 Year Renaissance, which aired on PBS. He can be reached at [email protected].