Gradle process isolation not setting JVM memory args correctly

Describe the bug Using 2.0.0-Beta on a large multi-module project, I get OOMs when running ./gradlew dokkaGenerate. To attempt to fix this, I've tried adding the following section to my top level build.gradle.kts:

    dokkaGeneratorIsolation = ProcessIsolation {
        minHeapSize = "4g"
        maxHeapSize = "8g"
    }

I've also tried with explicit sets:

    dokkaGeneratorIsolation.set(ProcessIsolation {
        minHeapSize.set("4g")
        maxHeapSize.set("8g")
    })

I'm still getting OOMs because Gradle workers are launched with -Xmx512m. From ps:

502 60919 60882   0  4:03PM ??         0:49.40 /Library/Java/JavaVirtualMachines/temurin-21.jdk/Contents/Home/bin/java -XX:+HeapDumpOnOutOfMemoryError -XX:+AlwaysPreTouch @/Users/mroberts/.gradle/.tmp/gradle-worker-classpath5758653660898353623txt -Xmx512m -Dfile.encoding=UTF-8 -Duser.country=US -Duser.language=en -Duser.variant worker.org.gradle.process.internal.worker.GradleWorkerMain 'Gradle Worker Daemon 2'

I usually see 10 versions of these. Gradle is running with 12 parallel tasks.

Expected behaviour Workers should launch with Xms4g -Xmx8g

To Reproduce

Use the above dokka config in a Gradle multimodule project.

Dokka configuration Configuration of dokka used to reproduce the bug

Submodules are getting the Dokka plugin via a convention plugin:

plugins {
    kotlin("jvm")
    kotlin("plugin.assignment")
    kotlin("plugin.serialization")
    id("io.gitlab.arturbosch.detekt")
    id("org.jetbrains.dokka")
}

Dokka related config in root build.gradle.kts:

dependencies {
    project.allprojects.filterNot { proj -> proj.name == rootProject.name }.forEach { proj -> dokka(proj) }
}

dokka {
    moduleName.set(project.name)

    dokkaGeneratorIsolation = ProcessIsolation {
        minHeapSize = "4g"
        maxHeapSize = "8g"
    }

    dokkaSourceSets {
        configureEach {
            jdkVersion.set(JavaVersion.VERSION_21.majorVersion.toInt())
            languageVersion.set("1.9")
        }
    }

    dokkaPublications.html {
        outputDirectory.set(File("$projectDir/sphinx/source/_static/dokka"))
    }
}

gradle.properties:

org.gradle.parallel=true
org.gradle.caching=true
org.gradle.project.enablePTS=true
org.gradle.configuration-cache=true
org.gradle.configureondemand=false
org.gradle.daemon.idletimeout=60
org.jetbrains.dokka.experimental.gradle.pluginMode=V2Enabled
org.gradle.jvmargs=-Dfile.encoding=UTF-8 \
                   -Xmx4096M \
                   -XX:ThreadStackSize=4096 \
                   -XX:CompilerThreadStackSize=4096 \
                   -Dlog4j2.formatMsgNoLookups=true \
                   --add-opens=jdk.compiler/com.sun.tools.javac.api=ALL-UNNAMED \
                   --add-opens=jdk.compiler/com.sun.tools.javac.code=ALL-UNNAMED \
                   --add-opens jdk.compiler/com.sun.tools.javac.comp=ALL-UNNAMED \
                   --add-opens jdk.compiler/com.sun.tools.javac.file=ALL-UNNAMED \
                   --add-opens jdk.compiler/com.sun.tools.javac.jvm=ALL-UNNAMED  \
                   --add-opens jdk.compiler/com.sun.tools.javac.main=ALL-UNNAMED \
                   --add-opens=jdk.compiler/com.sun.tools.javac.parser=ALL-UNNAMED \
                   --add-opens=jdk.compiler/com.sun.tools.javac.processing=ALL-UNNAMED \
                   --add-opens jdk.compiler/com.sun.tools.javac.tree=ALL-UNNAMED \
                   --add-opens jdk.compiler/com.sun.tools.javac.util=ALL-UNNAMED \
                   --add-opens java.base/java.time=ALL-UNNAMED

Installation

Operating system: macOS
Build tool: Gradle 8.11
Dokka version: 2.0.0-Beta

Kotlin / dokka

Gradle process isolation not setting JVM memory args correctly #3933