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Release Announcement v1.9.0

We are pleased to announce that the Apache YuniKorn community has voted to release 1.9.0. Apache YuniKorn is a standalone resource scheduler, designed for managing and scheduling Batch and Data workloads on container orchestration frameworks like Kubernetes for on-prem and on-cloud use cases.

Overview​

The Apache YuniKorn community has resolved 101 JIRAs in this release.

Release manager: Wilfred Spiegelenburg

Release date: 2026-07-29

Highlights​

Plugin mode removal​

As per the documented deprecation and removal of the plugin mode the plugin has now been completely removed. All plugin mode code has been removed. The build and test setups no longer reference the plugin mode. All deployments that use the plugin must migrate to the standard mode as part of the YuniKorn 1.9 upgrade. See YUNIKORN-3210 for details.

Kubernetes 1.35 support​

Apache YuniKorn 1.9.0 add supports for Kubernetes 1.35. K8s 1.36 is not supported in this release but has passed the standard e2e test suites. See YUNIKORN-3211 for details.

GOMEMLIMIT setting automatic calculation​

To help the Go GC runs the helm charts allowed setting a fixed value for the GOMEMLIMT via goMemoryLimit. The setting required manual updates and checks. The manual process has been replaced with an automatic calculation using the goMemoryLimitPercentage setting.
See YUNIKORN-3212 for details.

Possible deadlock in reservation release​

If a node is reserved by an application, and the same application searches for victims on the same node during the preemption cycle the release of the reservation would deadlock.

The issue was introduced in YuniKorn 1.8.0. See YUNIKORN-3318 for details.

Foreign allocation tracking​

In certain cases the informers for pods do not provide a pod create event followed by an update but only an update event. In case the pod is a foreign allocation this would result in the allocation not being present in the core. The missing allocation shows as an underutilised node causing scheduling failures.

The issue was introduced in YuniKorn 1.8.0. See YUNIKORN-3317 for details.

Quota change preemption phase 2​

Quota change preemption as added in YuniKorn 1.8 has had a number of improvements added. Delay inheritance, consecutive changes to the configuration and e2e testing added.
See YUNIKORN-3203 for details.

Web UI V2 off by default​

The development of the web UI V2 stalled. The current version is not in a usable state and turned off by default not only in the release branches but also in the master branch. See YUNIKORN-3302 for details.

Removal of legacy user processing​

Legacy user handling via the label yunikorn.apache.org/username has been removed in YuniKorn 1.9. The label method was deprecated in YuniKorn 1.6. YuniKorn 1.9 only supports the pod annotations for user details. See YUNIKORN-2634 for details.

Deprecations​

Removed node-utilization redirect from routes​

The /ws/v1/scheduler/node-utilization which was deprecated in YuniKorn 1.5 has been removed See YUNIKORN-3234

Removed deprecated settings from helm chart​

Deprecated settings have been removed from the helm chart. The documentation reflects this removal. The following deprecated settings have been removed:

  • operatorPlugins
  • placeholderImage
  • admissionController.processNamespaces
  • admissionController.bypassNamespaces
  • admissionController.labelNamespaces
  • admissionController.noLabelNamespaces
  • configuration

See YUNIKORN-3253 for details.

Credits​

The YuniKorn 1.9.0 release would not have been possible without the hard work of our community, and we would like to thank the following contributors to this release:

Aditya Maheshwari, Chung Chuan Wu, Manikandan R, Michael Chu, Mit Desai, Ompal Singh, Po Han Huang, Prakash Kumar Siddharth Krishna, Venkateshwaran Shanmugham, Victor Zhou, Wilfred Spiegelenburg, Xi Chen