docs/sglang_multiturn/search_tool_example.rst

=======================
Search Tool Integration

=======================

Last updated: 05/30/2025.

Introduction

------------
- We have added a search tool calling function to Multi-Turn RL, enabling the model to initiate retrieval requests during Actor rollout and directly use retrieval results for training. **We support using a local dense retriever as the retrieval tool, as well as integrating with your own local retrieval engine.**



Quick Reproduction

------------------

Create a New Docker Container

~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

.. code:: bash

   docker run \
       -it \
       --shm-size 32g \
       --gpus all \
       -v {Huggingface-Cache-Path}:/root/.cache \
       --ipc=host \
       --network=host \
       --privileged \
       --name sglang_{your-name} \
       lmsysorg/sglang:dev \
       /bin/zsh

If you need to restart after exiting the container:

.. code:: bash

   docker start -i sglang_{your-name}

Update Python and Configure the Virtual Environment using uv

~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

.. code:: bash

   apt update
   apt install -y python3.10 python3.10-venv

   # Create a virtual environment
   python3 -m venv ~/.python/verl-multiturn-rollout

   # Activate the virtual environment
   source ~/.python/verl-multiturn-rollout/bin/activate

   # Install uv
   python3 -m pip install uv

Install verl Upstream

~~~~~~~~~~~~~~~~~~~~~

.. code:: bash

   cd ~
   git clone https://github.com/volcengine/verl.git
   cd verl

   # Install verl
   python3 -m uv pip install .
   python3 -m uv pip install -r ./requirements_sglang.txt

   # Manually install flash-attn
   python3 -m uv pip install wheel
   python3 -m uv pip install packaging
   python3 -m uv pip install flash-attn --no-build-isolation --no-deps

Set Up a Local Retrieval Engine

~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

If you are using your own local retrieval service, you can skip this
step. We chose the local dense retriever provided in the search-R1
example; detailed instructions are in the `searchR1
docs <https://raw.githubusercontent.com/PeterGriffinJin/Search-R1/refs/heads/main/docs/retriever.md>`__.

In brief:



-  The GPU version offers higher accuracy and speed; each GPU uses about

   5–7 GB of memory.

-  The CPU version can be used for simple testing but has lower

   retrieval precision, which will degrade training performance. See the

   `retriever

   documentation <https://github.com/PeterGriffinJin/Search-R1/blob/main/docs/retriever.md>`__
   in search-R1 for details.
-  Recommend using Conda to install faiss-gpu=1.8.0; venv may cause errors.

**Note**: To start both the training process and the local retrieval
service, we launch two separate Python environments. The training uses
uv in the verl-multiturn-rollout environment, while the retriever uses
conda to install ``faiss-gpu``.

.. code:: bash

   # Download the Miniconda installer script
   wget https://repo.anaconda.com/miniconda/Miniconda3-latest-Linux-x86_64.sh -O ~/miniconda.sh

   # Install to $HOME/miniconda3 in batch mode
   bash ~/miniconda.sh -b -p $HOME/miniconda3

   # Activate conda (only in the current shell)
   eval "$($HOME/miniconda3/bin/conda shell.bash hook)"

   # (Optional) Add conda to your default shell startup
   conda init

   # Reload shell config
   source ~/.bashrc

   # Create and activate the retriever environment with Python 3.10
   conda create -n retriever python=3.10 -y
   conda activate retriever

   # Install PyTorch (with GPU support) and related libraries
   conda install pytorch==2.4.0 torchvision==0.19.0 torchaudio==2.4.0 pytorch-cuda=12.1 -c pytorch -c nvidia -y

   # Install other Python packages
   pip install transformers datasets pyserini huggingface_hub

   # Install the GPU version of faiss
   conda install faiss-gpu=1.8.0 -c pytorch -c nvidia -y

   # Install the API service framework
   pip install uvicorn fastapi

Download the Indexing and Corpus

~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

The local retrieval files are large—prepare sufficient disk space.
Downloading is about 60–70 GB, and uncompressed takes about 132 GB:

.. code:: bash

   conda activate retriever

   save_path=/the/path/to/save
   python examples/sglang_multiturn/search_r1_like/local_dense_retriever/download.py --save_path $save_path
   cat $save_path/part_* > $save_path/e5_Flat.index
   gzip -d $save_path/wiki-18.jsonl.gz

Start the Local flat e5 Retrieval Server

~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

1. The first startup will download models and load the index.
2. Apart from the download, startup takes about 1–2 minutes.
3. After startup, each GPU uses about 5–7 GB of memory, leaving the rest
   for multi-turn RL training.

.. code:: bash

   conda activate retriever

   index_file=$save_path/e5_Flat.index
   corpus_file=$save_path/wiki-18.jsonl
   retriever_name=e5
   retriever_path=intfloat/e5-base-v2

   python examples/sglang_multiturn/search_r1_like/local_dense_retriever/retrieval_server.py \
     --index_path $index_file \
     --corpus_path $corpus_file \
     --topk 3 \
     --retriever_name $retriever_name \
     --retriever_model $retriever_path \
     --faiss_gpu

Set Up WANDB_API_KEY

~~~~~~~~~~~~~~~~~~~~

.. code:: bash

   export WANDB_API_KEY={YOUR_WANDB_API_KEY}

   # Define a timestamp function
   function now() {
       date '+%Y-%m-%d-%H-%M'
   }

**Preprocess the Dataset**

~~~~~~~~~~~~~~~~~~~~~~~~~~

   **Note:** The following data processing and training commands must be
   run in the verl-multiturn-rollout environment.

.. code:: bash

   python3 examples/data_preprocess/preprocess_search_r1_dataset.py

Testing on 8 x H20

~~~~~~~~~~~~~~~~~~

.. code:: bash

   # Ensure the now() function is defined
   # Create a logs directory
   mkdir -p logs

   # Set GPUs and run with a suitable log path
   export CUDA_VISIBLE_DEVICES=0,1,2,3,4,5,6,7

   nohup bash examples/sglang_multiturn/search_r1_like/run_qwen2.5-3b_instruct_search_multiturn.sh \
     trainer.experiment_name=qwen2.5-3b-it_rm-searchR1-like-sgl-multiturn-$(now) \
     > logs/searchR1-like$(now).log 2>&1 &

Custom Search Configuration

---------------------------

To enable multi-turn reasoning, set the following fields in your config:

.. code:: yaml

   actor_rollout_ref:
     rollout:
       name: "sglang"
       multi_turn:
         enable: True

You must specify ``retrieval_service_url`` in ``examples/sglang_multiturn/config/tool_config/search_tool_config.yaml``, and properly configure concurrency. For more details on concurrency, refer to the Sandbox Fusion example:

.. code:: yaml

   tools:
     - class_name: verl.tools.search_tool.SearchTool
       config:
         retrieval_service_url: http://127.0.0.1:8000/retrieve
         num_workers: 120
         rate_limit: 120
         timeout: 30

The retriever input/output formats are as follows. If your service
parameters match, only modify ``retrieval_service_url``. You can also
customize in ``search_r1_like_utils.py``.

.. code:: python

   Input format:
   {
     "queries": ["What is Python?", "Tell me about neural networks."],
     "topk": 3,
     "return_scores": true
   }

   Output format (when return_scores=True, similarity scores are returned):
   {
       "result": [
           [   # Results for each query
               {
                   "document": doc, "score": score
               },
               # ... more documents
           ],
           # ... results for other queries
       ]
   }

Notes

-----

1. The total training time is about 27 hours; meanwhile, the validation
   dataset is very large (51 k), and each validation takes about 6000 s.
   (Therefore, ``val_before_train=False`` by default)