sgl-project/sglang · warning · ValueError

temp_set_env should not be used for sglang env vars

Error message

temp_set_env should not be used for sglang env vars

What it means

SGLang's test/helper utility temp_set_env refuses to set environment variables whose names start with SGLANG_ or SGL_. SGLang env vars are managed centrally through python/sglang/srt/environ.py, and ad-hoc mutation would bypass parsing, defaults, and deprecation handling.

Source

Thrown at python/sglang/srt/utils/common.py:1284

        return default
    try:
        return int(value)
    except ValueError:
        return default


@contextmanager
def temp_set_env(*, allow_sglang: bool = False, **env_vars: Any):
    """Temporarily set environment variables, restoring originals on exit.

    By default, SGLANG_*/SGL_* keys are rejected — use ``Envs`` descriptors
    for those.  Pass ``allow_sglang=True`` only for special env vars that
    intentionally bypass ``environ.py``.
    """
    if not allow_sglang:
        for key in env_vars:
            if key.startswith("SGLANG_") or key.startswith("SGL_"):
                raise ValueError("temp_set_env should not be used for sglang env vars")

    backup = {key: os.environ.get(key) for key in env_vars}
    try:
        for key, value in env_vars.items():
            if value is None:
                os.environ.pop(key, None)
            else:
                os.environ[key] = str(value)
        yield
    finally:
        for key, value in backup.items():
            if value is None:
                os.environ.pop(key, None)
            else:
                os.environ[key] = value


def support_triton(backend: str) -> bool:

View on GitHub (pinned to 0132848349)

Solutions

1. Register/define the variable in python/sglang/srt/environ.py and set it via the proper mechanism instead of temp_set_env
2. If the var is intentionally outside environ.py, pass allow_sglang=True explicitly
3. Prefer injecting configuration through ServerArgs/function parameters rather than env mutation

Example fix

# before
temp_set_env({"SGLANG_DISABLE_TOKENIZER_BATCH": "1"})
# after
temp_set_env({"SGLANG_DISABLE_TOKENIZER_BATCH": "1"}, allow_sglang=True)
# or better: use the environ.py accessor in test

def safe_temp_set_env(env_vars: dict) -> None:
    bad = [k for k in env_vars if k.startswith(('SGLANG_', 'SGL_'))]
    if bad and not getattr(safe_temp_set_env, 'allow_sglang', False):
        raise ValueError(f'register {bad} in environ.py instead')
    temp_set_env(env_vars, allow_sglang=getattr(safe_temp_set_env, 'allow_sglang', False))

When it happens

Trigger: Calling temp_set_env({'SGLANG_X': '1'}) or with any SGL_/SGLANG_-prefixed key without allow_sglang=True. Commonly hit in tests (test_from_env_bool, test_from_env_str) and in weight-loading or eval helpers that try to toggle features via env.

Common situations: Writing new tests that flip an SGLANG_ feature flag; refactoring code that previously used os.environ directly; adding a genuinely special env var that intentionally bypasses environ.py.

Related errors

• Unknown serve backend {name!r}. Available values: {available
• Multiple distributions register serve backend {name!r}: {pro
• Failed to load serve backend {name!r} from {self._entry_poin
• Serve backend {name!r} factory returned {type(backend).__nam
• Serve backend {name!r} uses API version {backend.api_version

AI-assisted analysis of sgl-project/sglang@0132848349 (2026-08-28). Data as JSON: /api/errors/758856fbe52a1044. Report an issue: GitHub.