Implementation:Volcengine Verl Package Init

Knowledge Sources	Volcengine_Verl
Domains	Package_Management, Initialization, API_Surface
Last Updated	2026-02-07 18:00 GMT

Overview

Concrete tool for initializing the verl package, exporting its public API, and applying platform-specific patches provided by the verl library.

Description

The verl/__init__.py module is the package entry point that performs several critical initialization tasks:

• Version loading — Reads __version__ from verl/version/version file
• Public API export — Exposes DataProto and __version__ via __all__
• Logging setup — Configures default WARNING-level logging
• External module loading — Imports user-specified external modules via VERL_USE_EXTERNAL_MODULES environment variable
• ModelScope integration — Optionally patches HuggingFace Hub to download from ModelScope when VERL_USE_MODELSCOPE=true
• NPU (Ascend) compatibility — When running on NPU hardware, applies patches for nested tensor operations and tensordict synchronization

Usage

This module is automatically executed when importing verl. Use from verl import DataProto to access the core data transfer protocol, or import verl; verl.__version__ to check the installed version.

Code Reference

Source Location

• Repository: Volcengine_Verl
• File: verl/__init__.py
• Lines: 1-103

Signature

# Public API
__all__ = ["DataProto", "__version__"]

# Key exports:
from .protocol import DataProto
__version__: str  # Read from verl/version/version

# Environment variables:
# VERL_USE_EXTERNAL_MODULES — Comma-separated list of external module paths to import
# VERL_USE_MODELSCOPE — Set to "true" to use ModelScope hub instead of HuggingFace

Import

from verl import DataProto
import verl
print(verl.__version__)

I/O Contract

Inputs

Name	Type	Required	Description
VERL_USE_EXTERNAL_MODULES	env var	No	Comma-separated module paths to import at init
VERL_USE_MODELSCOPE	env var	No	Set to "true" to enable ModelScope hub patching

Outputs

Name	Type	Description
DataProto	class	Core data transfer protocol class for inter-module communication
__version__	str	Package version string

Usage Examples

Basic Import

from verl import DataProto

# Create a DataProto from a dictionary
data = DataProto.from_single_dict({
    "input_ids": input_ids_tensor,
    "attention_mask": attention_mask_tensor,
})

Using External Modules

import os
os.environ["VERL_USE_EXTERNAL_MODULES"] = "my_custom_module,another_module"

import verl  # Will import my_custom_module and another_module at init

ModelScope Integration

import os
os.environ["VERL_USE_MODELSCOPE"] = "true"

import verl  # HuggingFace Hub is patched to use ModelScope

Related Pages

• Environment:Volcengine_Verl_Python_Core_Dependencies