Installing Optimizer Hub with Compilation Streaming

Step 1: Enable Compilation Streaming on the Server

Compilation Streaming requires one setting. Either add it to your values-override.yaml:

 
compilationStreaming:
  enabled: true

Or pass the values-comp-stream.yaml file shipped with the Helm chart, which contains the same setting.

The task-executor pod that builds the streams is deployed by default, so no second setting is needed.

 
helm install opthub opthub-helm/azul-opthub \
  -n my-opthub \
  -f values-override.yaml \
  -f values-comp-stream.yaml \
  --version 26.08.0

 
helm upgrade opthub opthub-helm/azul-opthub \
  -n my-opthub \
  -f values-override.yaml \
  -f values-comp-stream.yaml \
  --version 26.08.0

Step 2: Verify the Server

Check that the task-executor pod is running:

 
kubectl get pods -n my-opthub | grep task-executor

Step 3: Enable Compilation Streaming on the JVM

Add -XX:+CNCEnableCompilationStreaming to the JVM options of your application, alongside the options that connect it to Optimizer Hub and set its ReadyNow profile name:

 
java -XX:OptHubHost=<host>:<port> \
    -XX:+EnableRNO \
    -XX:ProfileName=<profile-name> \
    -XX:+CNCEnableCompilationStreaming \
    -jar my-app.jar

Optimizer Hub builds each stream from its Code Cache and the promoted ReadyNow profile for a given profile name, so the JVM must use the same -XX:ProfileName as the profile the stream was built from. For the other options that connect a JVM to Optimizer Hub, see Connecting a JVM to Optimizer Hub and Using ReadyNow Orchestrator.

At startup the JVM asks whether a stream exists for its profile. If one does, the JVM uses it. If not, the JVM runs normally without streaming and no error is reported.

Step 4: Verify the Client

Streaming statistics appear in the JVM’s GC log in the COMPSTREAMSTATS line, covering lookups, hits, misses, installation outcomes, segments loaded and evicted, and bytes downloaded. The hit rate derived from these values is the main indicator of whether streaming is working well for an application.

Compilation Streaming Requires a Promoted Profile

Optimizer Hub can only provide a stream after a ReadyNow profile has been promoted for the given profile name. If the promotion criteria configured for your deployment are never met, no stream is ever built, and JVMs continue without streaming.

This is not reported as an error. A JVM that finds no stream for its profile starts normally and the application behaves correctly, so an instance that appears healthy may not be using Compilation Streaming at all. If COMPSTREAMSTATS shows no hits, confirm that a promoted profile exists for your profile name before investigating anything else.

Promotion criteria are set per generation and are configurable, so how long promotion takes depends on your deployment. See Understanding ReadyNow Orchestrator Generations.