sgl-project/sglang · warning · DeprecationWarning

sglang.srt.layers.attention.nsa is deprecated; use sglang.sr

Error message

sglang.srt.layers.attention.nsa is deprecated; use sglang.srt.layers.attention.dsa instead.

What it means

Importing sglang.srt.layers.attention.nsa raises a DeprecationWarning at import time because the package is now a thin re-export shim over sglang.srt.layers.attention.dsa. All symbols still resolve via star-import, so code works, but the shim will be deleted.

Source

Thrown at python/sglang/srt/layers/attention/nsa/__init__.py:5

# [Deprecated] attention/nsa/ is a thin re-export shim for backward compatibility.
# Use attention/dsa/ instead. This directory will be removed in a future release.
import warnings

warnings.warn(
    "sglang.srt.layers.attention.nsa is deprecated; "
    "use sglang.srt.layers.attention.dsa instead.",
    DeprecationWarning,
    stacklevel=2,
)
from sglang.srt.layers.attention.dsa import *  # noqa: F401, F403

View on GitHub (pinned to 0132848349)

Solutions

1. Rewrite imports to use sglang.srt.layers.attention.dsa
2. Grep the codebase for 'attention.nsa' and update all matches
3. Run with -W error::DeprecationWarning in CI to surface latent imports

Example fix

# before
from sglang.srt.layers.attention.nsa import NativeSparseAttnBackend
# after
from sglang.srt.layers.attention.dsa import NativeSparseAttnBackend

import importlib, warnings
with warnings.catch_warnings():
    warnings.simplefilter("error", DeprecationWarning)
    importlib.import_module("my_pkg")  # surfaces legacy nsa imports

def uses_deprecated_nsa(module_source: str) -> bool:
    return "attention.nsa" in module_source

When it happens

Trigger: Any 'import sglang.srt.layers.attention.nsa' or 'from sglang.srt.layers.attention.nsa import ...' statement, including transitive imports from third-party patches or old code.

Common situations: Custom model files or monkey-patches importing from the old nsa path; upgrading sglang in a repo with vendored attention code.

Related errors

• attention-backend='nsa' is deprecated; use 'dsa' instead. Th
• sglang.srt.layers.attention.nsa.dequant_k_cache is deprecate
• sglang.srt.layers.attention.nsa.index_buf_accessor is deprec
• sglang.srt.layers.attention.nsa.transform_index is deprecate
• sglang.srt.layers.attention.nsa.nsa_backend_mtp_precompute i

AI-assisted analysis of sgl-project/sglang@0132848349 (2026-08-28). Data as JSON: /api/errors/ad5e965f660d930b. Report an issue: GitHub.