Runtime

These settings define how runtime-specific recommendations are applied to workloads

Java runtime

You can define how Optimize Live applies JVM max heap size recommendations to JVM containers.

The Java max heap recommendation settings apply to workloads identified as JVM workloads that Optimize Live is able to collect JVM metrics for. For non-Java workloads, these settings will have no effect.

StormForge by default assumes that Java applications use the -XX:MaxRamPercentage heap size management mechanism, and that changing the container’s memory limit will therefore change the effective max heap size. StormForge will attempt to use this relationship to optimize heap size without changing any configuration for your app.

If an app does not use -XX:MaxRamPercentage, you will need to adjust the max heap patch path setting to define another way of automating the heap size.

For more information about Java recommendations, see Java heap size.

Max heap patch path

Specifies where the value for Java Max Heap should be in the Optimize Live patch.

Annotation Default value
live.stormforge.io/containers.java.max-heap.patch-path -
Description

This setting controls how Optimize Live applies its recommended max heap value to workloads.

If you don’t configure a patch-path, Optimize Live won’t directly update a specific value for max heap anywhere in the workload. Instead, Optimize Live will take the JVM’s observed MaxRamPercentage as a constant and adjust the container’s memory limit in order to change the heap size.

If you configure a patch-path, Optimize Live will instead inject the recommended max heap value into the workload at the location you specify.

In order to: Set patch-path to:
Use the memory limit to effect changes to heap size - (or None)
Set heap values using an environment variable {{ .EnvVarPath "STORMFORGE_JAVA_ARGS" }}
Set heap value in a custom field (JSON pointer) /spec/{{ .ContainerName }}/jvm-max-heap

Max heap patch format

Specifies how to format the Java Max Heap recommended value in Optimize Live patches.

Annotation Default value
live.stormforge.io/containers.java.max-heap.patch-format None
Description

The format Optimize Live uses when it injects a recommended value into a workload can be customized by setting a patch-format.

If you don’t configure a specific patch-format, Optimize Live’s default behavior is to produce a MaxRamPercentage setting (-XX:MaxRamPercentage=VALUE) if the workload has a memory limit. If the workload does not have a memory limit, it will produce a MaxHeapSize setting (-XX:MaxHeapSize=VALUE) instead.

This setting has no effect when patch-path is set to -.

In order to: Set patch-format to:
Let Optimize Live pick how to output max heap setting None
Produce a -XX:MaxRamPercentage setting {{ jvmOption "-XX:MaxRamPercentage" (round (.MemoryLimit.AsApproximateFloat64 | divf .Value.AsApproximateFloat64 | mulf 100) 2 1) }}
Produce a -XX:MaxHeapSize setting {{- jvmOption "-XX:MaxHeapSize" .Value }}

Minimum and maximum bounds for max heap

Values indicate the lower bound and upper bound of the range for Java max heap.

Annotation Default value
live.stormforge.io/containers.java.max-heap.min None
live.stormforge.io/containers.java.max-heap.max None
Description

The minimum and maximum bounds for Java max heap acts a constraint on what max heap values Optimize Live will recommend, regardless of the observed heap usage. These bounds can be used to set a floor below which the max heap should never drop and a ceiling above which Optimize Live will never raise it.

When used as defaults for the cluster, max heap bounds can be used to implement default automation policies such as “never set max heap of less than 128Mi” or “never set max heap higher than 8192Gi”.

Related topics

Recommendations > Java heap size

Recommendations for Java workloads

Last modified March 24, 2025