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Slime — RL post-training for LLMs with Megatron and SGLang

Slime — RL post-training for LLMs with Megatron and SGLang

Developer13 minutes3 questions2026-08-09
The idea in one minute

Start with meaning, then move to detail.

This lesson explains Slime — RL post-training for LLMs with Megatron and SGLang as part of Hermes internals and extension points. You will learn what it does, when it matters, and the smallest safe test that proves it works.

If you are new

If you are new, do not memorize names. Focus on three questions: what problem does this solve, what access does it need, and how can you verify the result?

For hands-on use

For practice, inspect the first example, identify its effects, run it on test data, and compare the result with the source claim.

For specialists

For advanced readers, inspect Skill metadata, Reference: full SKILL.md, When to Use slime, then verify failure modes and version compatibility.

What do you need first?

Know Python, Git, and basic project structure before changing code.

What will you know?

A clear outcome before you read.

  • Understand Slime — RL post-training for LLMs with Megatron and SGLang without assumed prior knowledge.
  • Separate the source description from what still needs testing in your environment.
  • Read the first command and identify its inputs and outputs before copying it.
Lesson terms

Short definitions before the details.

Skill
An instruction bundle that teaches Hermes a repeatable workflow without necessarily adding an external service.
Official page description

RL post-training for LLMs with Megatron and SGLang

Topic map

What does the source say, and in what order?

  1. 01
    Skill metadata

    Start here to understand the core idea or structure.

  2. 02
    Reference: full SKILL.md

    Read this after the foundation, then connect it to the previous step.

  3. 03
    When to Use slime

    Read this after the foundation, then connect it to the previous step.

  4. 04
    Key Features

    Read this after the foundation, then connect it to the previous step.

  5. 05
    Architecture Overview

    Read this after the foundation, then connect it to the previous step.

  6. 06
    Installation

    Read this after the foundation, then connect it to the previous step.

  7. 07
    From Source

    Read this after the foundation, then connect it to the previous step.

  8. 08
    Quick Start: GRPO Training

    Read this after the foundation, then connect it to the previous step.

  9. 09
    Workflow 1: Standard GRPO Training

    Read this after the foundation, then connect it to the previous step.

  10. 10
    Prerequisites Checklist

    Finish here to verify the result and special cases.

Examples from the official page

Copy only after you understand the effect.

┌─────────────────────────────────────────────────────────┐ │ Data Buffer │ │ - Prompt initialization and management │ │ - Custom data generation and filtering │ │ - Rollout sample storage │ └─────────────┬───────────────────────────┬───────────────┘ │ │ ┌─────────────▼───────────┐ ┌─────────────▼───────────────┐ │ Training (Megatron-LM) │ │ Rollout (SGLang + Router) │ │ - Actor model training │ │ - Response generation │ │ - Critic (opti
# Recommended: Docker docker pull slimerl/slime:latest docker run --rm --gpus all --ipc=host --shm-size=16g \ -it slimerl/slime:latest /bin/bash # Inside container cd /root/slime && pip install -e . --no-deps
git clone https://github.com/THUDM/slime.git cd slime pip install -r requirements.txt pip install -e .
Try it now

Read the first command and identify its inputs and outputs before copying it.

Match every command to your installed Hermes version, review the files and accounts it can reach, and use non-sensitive data for the first test. If this explanation differs from the source, the official source wins.

Knowledge check

Three decisions before completion.

1. What is the source of truth when “Slime — RL post-training for LLMs with Megatron and SGLang” changes?
2. What is the best way to apply this lesson?
3. What should happen before a step can modify files or an external account?