Rollout Service API

The Rollout service generates training samples using SGLang engines. It is deployed as a Ray Serve deployment with a FastAPI ingress, exposing HTTP endpoints for lifecycle management, evaluation, and async weight-update coordination.

Overview

Property	Value
Module	relax.components.rollout
Deployment	@serve.deployment
Ingress	FastAPI

Lifecycle

The Rollout runs a background loop that:

1. Generates samples via RolloutManager.generate() using SGLang engines
2. Computes rewards via pluggable reward functions (rm_hub/)
3. Publishes data to TransferQueue for the Actor to consume
4. Optionally triggers evaluation at configured intervals
5. Manages staleness bounds to avoid data drift

Async Weight Coordination

In fully-async mode, the Rollout service coordinates with the Actor for weight updates:

1. Actor calls /can_do_update_weight_for_async to check if rollout can pause
2. Rollout pauses if data production is complete for current step
3. Actor pushes new weights
4. Actor calls /end_update_weight to resume rollout

HTTP Endpoints

Source

• Implementation: relax/components/rollout.py
• Base class: relax/components/base.py