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Everything you need to know about upgrading Java on z/OS

By Ulrica Cheng posted Wed February 28, 2024 08:40 AM

  
Support lifecycle for IBM Semeru

 

Does thinking about upgrading your Java programs give you a headache? There are a million reasons to do it, but it’s difficult to know where to begin. That’s why we’ve compiled resources for migrating from IBM® SDK, Java™ Technology Edition to IBM Semeru Runtime Certified Edition for z/OS in a portal at IBM Java SDK and Semeru Runtime Migration on z/OS.   

Why should I upgrade my Java version to the latest version?

Aside from new Java language features, OpenJDK class libraries, the Eclipse J9 virtual machine, and Java APIs, migrating to Java 11, 17, or 21 provides improved security features and performance enhancements. Read more about why you should upgrade at Why migrate to the latest version of the IBM Semeru Runtime Certified Edition for z/OS.

How do I upgrade?

Depending on which version you are upgrading to and from, the process varies.

You might be upgrading from:

  • IBM Java SDK 8 (Java 8) to Semeru Runtime 11 (Java 11)
  • Java 8 to Semeru Runtime 17 (Java 17)
  • Java 8 to Semeru Runtime 21 (Java 21)
  • Java 11 to Java 17
  • Java 11 to 21
  • Java 17 to Java 21
  • From a version previous to Java 8

Explore the portal to help you select the upgrade path that best suits your needs. We’ve also highlighted key considerations, such as security, planning, middleware, and details about the support timeline.

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Comments

James Tang
Fri March 08, 2024 10:21 AM

I see, so I think you're looking for a convenience list of software for z/OS that supports Semeru 17, perhaps similar to this (note this one is not exhaustive) - https://community.ibm.com/community/user/ibmz-and-linuxone/blogs/james-tang1/2023/01/13/ecosystem-support-of-semeru-11-java-11-on-zos
While such list doesn't exist for Semeru 17 today, it is an excellent feedback for the portal, if you don't mind submitting this.
The other reference point, in case you're not aware, is the IBM Software Product Compatibility Reports tool (linked in the portal) that should list out whether a particular level of Java is supported by a chosen software - https://www.ibm.com/software/reports/compatibility/clarity/index.html
The v11 blog above tried to simplify UX by consolidating the output of this SPCR tool.

On benchmarking, yes, totally agree that performance is highly dependent on the particular Java app and what it uses. Many clients go through an extensive performance testing and tuning phase, to ensure all SLAs can be met, before they deploy into production.

Gregory DeBo
Thu March 07, 2024 06:00 PM

Thanks for the quick response James.  While I appreciate that IBM does benchmarks, we often saw that our actual experience could differ because our production workloads were very different than the workloads that are run in a controlled lab environment, that’s why I was interested in reviewing customer experiences.

Regarding compatibility, the portal didn’t really have what I was looking for.  I was trying to find a matrix that would show what IBM tools do and do not support Java 17.  I already know that Application Performance Analyzer does not, was just trying to prevent other surprises.  When I look at the Known issues and Limitations page, it says there are no known issues, but I view tools not working as an issue.

James Tang
Thu March 07, 2024 05:24 PM

Hello Gregory, thanks for your comments. I'm the Java on IBM Z lead and can help with answering some of your questions. We have seen successful upgrades to Semeru 17 on z/OS. We have regular practice to do release-to-release performance benchmark, to ensure performance is same or better than previous release. Regarding compatibility, please refer to the migration guides captured in the portal above. We welcome any feedback about the portal (Feedback button in the middle of page) to make it better for our users.

If you're interested to participate in a sponsor feedback program, please let me know by sending me a private message, and we can get the ball rolling. Thanks!

Gregory DeBo
Thu March 07, 2024 07:21 AM

Are you aware of any customers that have already moved to Java 17 on z/OS and have shared their experiences performance wise?  When we participated in Db2 Early Support Programs,  some of the companies, including us, would do presentations at the end of the program.  I wasn’t sure whether there was anything similar for Java.  Or any compatibility issues that they ran into would also be helpful.  We are already aware one IBM tool that does not support Java 17, is there a compatibility matrix that exists that provides a complete picture?