Azul OpenJDK

Migrating from Oracle JDK to Azul OpenJDK

Azul OpenJDK

Migrating from Oracle JDK to Azul OpenJDK

To migrate from Oracle JDK to Azul OpenJDK:

  • Assess Current Environment: Catalog your Java applications using Oracle JDK.
  • Select Azul OpenJDK Version: Choose a compatible version of Azul OpenJDK.
  • Set Up Testing Environment: Establish a controlled environment for testing the migration.
  • Phase-wise Migration: Start with less critical applications, then move to more complex ones.
  • Conduct Thorough Testing: Test applications for functionality, performance, and security.
  • Remove Oracle JDK Runtime: After successful testing, fully transition to Azul OpenJDK.
  • Monitor Post-Migration: Continually monitor performance in the new environment.
  • Optimize and Update: Adjust configurations for optimal performance with Azul OpenJDK.

Introduction to JDK Migration

azul java

The migration from Oracle JDK to Azul OpenJDK is significant for many organizations relying on Java for their applications.

This transition is driven by a need for a more cost-effective and flexible Java Development Kit (JDK) solution.

  • Why Migrate?: In recent years, Oracle’s changes to Java SE subscription pricing have prompted organizations to seek more affordable alternatives. Azul OpenJDK emerges as a viable option, offering a similar level of performance and security as Oracle JDK but with potentially lower costs and more flexible licensing terms.
  • Migration Landscape: The landscape for JDK migration is evolving, with more enterprises looking towards OpenJDK distributions like Azul for their Java application needs. Key motivators for this shift include cost savings, compliance with licensing terms, and a desire for better support and maintenance options.

Pre-Migration Planning and Assessment

Before embarking on the migration journey, conducting thorough planning and assessment is crucial to ensure a successful transition.

  • Evaluating Java Applications: Start by assessing your current Java application landscape. This involves reviewing all applications running on Oracle JDK to understand their dependencies, configurations, and specific JDK requirements.
  • Scope of Migration: Determine the migration size by identifying which applications will be moved to Azul OpenJDK. This can range from a few critical applications to a complete overhaul of all Java applications within the organization.
  • Identifying Challenges: Recognize potential challenges, such as compatibility issues, performance impacts, or specific features unique to Oracle JDK. This step is crucial for mitigating risks associated with the migration.
  • Migration Strategy: Develop a comprehensive migration strategy, including a detailed plan for the transition process, timelines, resource allocation, and contingency plans. The strategy should also outline the testing and validation processes to ensure that applications continue to perform optimally post-migration.

Proper planning and assessment are the bedrock of a successful migration from Oracle JDK to Azul OpenJDK. They ensure that organizations can leverage the benefits of Azul OpenJDK while minimizing disruption to their Java applications​.

Migration Process

Migration Process

Installing Azul OpenJDK

  1. Download the Installer: Visit the official Azul website and download the appropriate OpenJDK distribution for your operating system.
  2. Install the JDK: Follow the installation instructions specific to your operating system. Ensure that you select the correct installation path and set environment variables appropriately.
  3. Set JAVA_HOME: Update the JAVA_HOME environment variable to point to the new Azul OpenJDK installation directory.
  4. Update PATH: Add the bin directory of Azul OpenJDK to your system PATH to make the new Java commands available globally.

Testing Compatibility and Performance

  1. Run Unit Tests: Execute your existing unit tests to ensure your codebase is compatible with Azul OpenJDK.
  2. Benchmark Performance: Use performance benchmarking tools to measure any differences in application performance between Oracle JDK and Azul OpenJDK.
  3. Load Testing: Perform load testing to simulate real-world usage and verify Azul OpenJDK can handle your application’s workload.

Addressing Any Compatibility Issues

  1. Identify Issues: Monitor test results for any failures or performance regressions.
  2. Research Solutions: Consult the Azul OpenJDK documentation and community forums for known issues and recommended solutions.
  3. Modify Code: Make necessary changes to your codebase to resolve compatibility issues. This might involve updating deprecated APIs or refactoring problematic code.
  4. Retest: After making changes, rerun your tests to confirm that the issues have been resolved.

Gradually Transitioning Applications

  1. Pilot Migration: Start with a small, non-critical application to pilot the migration process. This allows you to identify and address any issues on a smaller scale before a full rollout.
  2. Incremental Rollout: Gradually migrate additional applications, one at a time. This reduces the risk of widespread issues and allows for more manageable troubleshooting.
  3. Dual-Run Period: Consider running Oracle JDK and Azul OpenJDK in parallel to compare performance and stability directly.

Monitoring and Validating the Migration

  1. Continuous Monitoring: Use monitoring tools to continuously track application performance and stability. Look for response time, memory usage, and CPU load metrics.
  2. User Feedback: Gather end-user feedback to identify issues that may not have been detected during testing.
  3. Regular Reviews: Conduct regular reviews of the migration process and adjust as needed to ensure ongoing success.

Top 4 Best Practices for JDK Migration

Top 4 Best Practices for JDK Migration

Strategies for Efficient and Secure Migration

  1. Risk Assessment: Conduct a thorough risk assessment to identify potential issues and plan for mitigation strategies.
  2. Gradual Rollout: Implement the migration in phases to manage risks and ensure stability.
  3. Security Measures: Ensure all security features of Oracle JDK are effectively replicated or replaced in the new environment.
  4. Compliance Checks: Regularly verify compliance with software licensing and industry regulations.

Common Pitfalls to Avoid and How to Overcome Them

  1. Underestimating Testing Needs: Allocate sufficient time and resources for thorough testing to catch issues early.
  2. Overlooking Dependency Management: Be vigilant about dependencies that might be affected by the JDK switch.
  3. Ignoring Performance Metrics: Monitor performance metrics post-migration to ensure the system operates optimally.
  4. Neglecting Training and Support: Provide adequate training and support to your team for adapting to the new JDK environment.
  5. Lack of a Rollback Plan: Always have a contingency plan to revert to the previous state in case of critical issues during migration.

Adhering to these best practices and being mindful of common pitfalls can greatly enhance the success rate of migrating from Oracle JDK to Azul OpenJDK, ensuring a seamless and secure transition​.

Post-Migration: Monitoring and Optimization

migration azul java

Methods for Monitoring Java Applications Post-Migration

  1. Performance Metrics: Regularly monitor key performance indicators to ensure the Java applications run optimally on Azul OpenJDK.
  2. Error and Log Analysis: Implement robust logging and error tracking to quickly identify and address any issues post-migration.
  3. User Feedback: Gather feedback from end-users and developers to assess any practical challenges or performance issues.

Tips for Optimizing Performance and Cost in the New Environment

  • Resource Utilization: Analyze resource usage to optimize allocation and reduce costs, especially in cloud environments.
  • Update and Patch Management: Keep the Azul OpenJDK version updated to benefit from performance improvements and security patches.
  • Fine-Tuning Configurations: Adjust Java Virtual Machine (JVM) settings and configurations for optimal performance specific to your applications.

Common Challenges and Solutions

Common Challenges and Solutions

Compatibility Issues with Libraries and Frameworks

  1. Identify Problematic Libraries: Use dependency analysis tools to identify libraries and frameworks that may not be fully compatible with Azul OpenJDK.
  2. Update Dependencies: Where possible, update to the latest versions of libraries and frameworks that are compatible with OpenJDK.
  3. Alternative Libraries: If an update is not possible, consider replacing problematic libraries with alternatives compatible with Azul OpenJDK.

Performance Discrepancies

  1. Benchmark Comparisons: Regularly benchmark performance before and after migration to identify discrepancies.
  2. Optimize Code: Profile and optimize your application code to address performance bottlenecks.
  3. Tuning Options: Explore JVM tuning options provided by Azul OpenJDK to enhance performance. Adjust garbage collection settings, memory allocation, and other JVM parameters.

Addressing Security Concerns

  1. Security Updates: Ensure you regularly apply security updates and patches provided by Azul.
  2. Security Audits: Conduct regular security audits of your application and the underlying JDK to identify and mitigate vulnerabilities.
  3. Compliance Checks: Verify that your use of Azul OpenJDK complies with relevant security and regulatory requirements.

Ensuring Ongoing Support and Updates

  1. Support Plans: Consider subscribing to a support plan from Azul to access professional support and timely updates.
  2. Community Resources: Utilize community forums, mailing lists, and online resources to stay informed about updates and best practices.
  3. Regular Maintenance: Schedule regular maintenance windows to apply updates, perform system checks, and ensure your environment remains up-to-date and secure.


How should organizations start their migration from Oracle JDK to Azul OpenJDK?

Begin by assessing your current environment, which involves cataloging all Java applications that use Oracle JDK to understand the scope and requirements of the migration process.

How do you choose the right version of Azul OpenJDK for migration?

Select a version of Azul OpenJDK that is compatible with your applications and systems. Consider your current Java version and check Azul’s documentation for compatibility and support. your current Java version

What is the importance of setting up a testing environment for migration?

Establishing a controlled testing environment is crucial for safely testing the migration without affecting your production systems. This allows you to identify and resolve any issues before the full migration.

Should the migration to Azul OpenJDK be done all at once?

A phase-wise migration is recommended, starting with less critical applications to minimize risk. Once these have been successfully migrated and tested, you can proceed to more complex and critical applications.

What are key areas to focus on during testing?

During testing, verify that applications maintain their functionality, performance, and security standards on Azul OpenJDK. This ensures a smooth transition with minimal impact on your operations.

When is it safe to remove Oracle JDK runtime from the system?

You should remove Oracle JDK runtime only after thorough testing confirms that your applications are running successfully on Azul OpenJDK, ensuring no dependencies on the Oracle JDK runtime.

Why is continuous monitoring important after migrating to Azul OpenJDK?

Continual monitoring after migration helps quickly identify and address any performance issues or bugs in the new environment, ensuring stability and efficiency.

How can organizations optimize their applications post-migration?

After migration, you may need to adjust configurations or update application code to optimize performance with Azul OpenJDK. Stay informed on updates and best practices from Azul to keep your applications running optimally.

What are the benefits of migrating to Azul OpenJDK from Oracle JDK?

Migrating to Azul OpenJDK can offer organizations more flexibility in licensing, potentially lower costs, and access to a robust community for support and innovation.

Are there any risks associated with migrating from Oracle JDK to Azul OpenJDK?

As with any major system change, compatibility or performance impacts are risks. However, these can be minimized with thorough testing and phased migration strategies.

How can organizations mitigate migration risks?

Mitigate migration risks by conducting comprehensive testing, starting with non-critical applications, and closely monitoring the system post-migration for any issues.

What support is available for organizations migrating to Azul OpenJDK?

Azul provides documentation and support services for organizations migrating to their OpenJDK version. Community support and resources are also available for troubleshooting and advice.

Can the migration process be automated?

While parts of the migration process can be automated, such as deploying the new JDK, careful manual review and testing are essential to ensure that all aspects of the applications work as expected.

How does migrating to Azul OpenJDK impact application security?

Security should remain a priority during and after the migration. Azul OpenJDK releases include security updates, but applications should be tested specifically for security to ensure no new vulnerabilities.

What steps should be taken if issues arise post-migration?

If issues arise post-migration, replicate and diagnose them using the testing environment. Then, support from Azul and the broader OpenJDK community will be used to find solutions and implement fixes promptly.


  • Fredrik Filipsson

    Fredrik Filipsson brings two decades of Oracle license management experience, including a nine-year tenure at Oracle and 11 years in Oracle license consulting. His expertise extends across leading IT corporations like IBM, enriching his profile with a broad spectrum of software and cloud projects. Filipsson's proficiency encompasses IBM, SAP, Microsoft, and Salesforce platforms, alongside significant involvement in Microsoft Copilot and AI initiatives, improving organizational efficiency.

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