How to pass JVM options to KafkaConnect with the exact order?

[mikekamornikov]

The following config after being applied

jvmOptions:
  -XX:
    ExitOnOutOfMemoryError: true
    InitialRAMPercentage: 30
    MaxHeapFreeRatio: 30
    MaxRAMPercentage: 80
    MinHeapFreeRatio: 10
    UnlockExperimentalVMOptions: true
    UseShenandoahGC: true
    ShenandoahUncommit: true
    ShenandoahGCHeuristics: compact

results into

jvmOptions:
  -XX:
    ExitOnOutOfMemoryError: true
    InitialRAMPercentage: 30
    MaxHeapFreeRatio: 30
    MaxRAMPercentage: 80
    MinHeapFreeRatio: 10
    ShenandoahGCHeuristics: compact
    ShenandoahUncommit: true
    UnlockExperimentalVMOptions: true
    UseShenandoahGC: true

The pod crashes with

Error: VM option 'ShenandoahUncommit' is experimental and must be enabled via -XX:+UnlockExperimentalVMOptions.
Error: The unlock option must precede 'ShenandoahUncommit'.
Error: Could not create the Java Virtual Machine.
Error: A fatal exception has occurred. Program will exit.

Is there any ENV I can use to pass OPTS string as a whole?

[mikekamornikov]

It's the same one - #3418

[mikekamornikov]

BTW, I've found the following:

private static final Set<String> JVM_PERFORMANCE_PRIORITY_OPTIONS = Set.of("UnlockDiagnosticVMOptions");

Probably this property could contain more Unlock flags.

[scholzj]

Feel free to open a PR for it if you want.

[mikekamornikov]

So far it looks like the following works fine:

jvmOptions:
  -Xmx: 1000M
resources:
  limits:
    memory: 1600Mi
  requests:
    cpu: 100m
    memory: 1200Mi
template:
  connectContainer:
    env:
    - name: KAFKA_JVM_PERFORMANCE_OPTS
      value: "-XX:+ExitOnOutOfMemoryError -XX:MinHeapFreeRatio=10 -XX:MaxHeapFreeRatio=30 -XX:+UnlockExperimentalVMOptions -XX:+UseShenandoahGC -XX:+ShenandoahUncommit -XX:ShenandoahGCHeuristics=compact"

• .spec.template. connectContainer. env sets the ENV which is usually calculated from .spec.jvmOptions.-XX
• .spec.jvmOptions.-Xmx causes generation of KAFKA_HEAP_OPTS env, so heap settings are not calculated automatically. Probably setting empty KAFKA_HEAP_OPTS has the same effect.