fix(server): reuse Fun-ASR-Nano fallback after vLLM failure (#3402)

Closes #3401.

funasr/bin/_server_app.py

@@ -150,7 +150,7 @@ def create_app(device: str = "cuda", preload_model: str = "auto", model_path: st
 
     def _load_vllm_engine():
         """Load Fun-ASR-Nano vLLM engine. Falls back to AutoModel if vLLM unavailable."""
-        if app.state.engine is not None:
+        if app.state.engine is not None or "fun-asr-nano" in app.state.fallback_models:
             return
         try:
             from funasr.models.fun_asr_nano.inference_vllm import FunASRNanoVLLM
@@ -162,7 +162,7 @@ def create_app(device: str = "cuda", preload_model: str = "auto", model_path: st
             # cases, honor the server-level hub selection.
             vllm_model = app.state.model_path if app.state.model_path else "FunAudioLLM/Fun-ASR-Nano-2512"
             vllm_hub = app.state.hub
-            app.state.engine = FunASRNanoVLLM.from_pretrained(
+            engine = FunASRNanoVLLM.from_pretrained(
                 model=vllm_model,
                 hub=vllm_hub,
                 device=device,
@@ -171,10 +171,12 @@ def create_app(device: str = "cuda", preload_model: str = "auto", model_path: st
                 gpu_memory_utilization=0.5,
             )
             logger.info(f"vLLM engine ready in {time.time()-t0:.1f}s")
-            app.state.use_vllm = True
 
             logger.info("Loading VAD model...")
-            app.state.vad_model = _AutoModel(model="fsmn-vad", device=device, disable_update=True)
+            vad_model = _AutoModel(model="fsmn-vad", device=device, disable_update=True)
+            app.state.engine = engine
+            app.state.vad_model = vad_model
+            app.state.use_vllm = True
             logger.info("VAD ready.")
         except Exception as e:
             logger.warning(f"vLLM failed ({e}), falling back to AutoModel for fun-asr-nano")

tests/test_server_app_openai_segments.py

@@ -1,8 +1,11 @@
+import asyncio
 import importlib.util
 import sys
 import types
 from pathlib import Path
 
+import pytest
+
 
 REPO_ROOT = Path(__file__).resolve().parents[1]
 SERVICE_PATH = REPO_ROOT / "funasr" / "bin" / "_server_app.py"
@@ -12,12 +15,21 @@ def load_server_app(monkeypatch):
     class DummyFastAPI:
         def __init__(self, *args, **kwargs):
             self.state = types.SimpleNamespace()
+            self.routes = {}
 
-        def post(self, *args, **kwargs):
-            return lambda func: func
+        def post(self, path, *args, **kwargs):
+            def decorator(func):
+                self.routes[("POST", path)] = func
+                return func
 
-        def get(self, *args, **kwargs):
-            return lambda func: func
+            return decorator
+
+        def get(self, path, *args, **kwargs):
+            def decorator(func):
+                self.routes[("GET", path)] = func
+                return func
+
+            return decorator
 
     fastapi_stub = types.ModuleType("fastapi")
     fastapi_stub.FastAPI = DummyFastAPI
@@ -41,14 +53,27 @@ def load_server_app(monkeypatch):
     return module
 
 
-def install_dummy_funasr(monkeypatch):
+def install_dummy_funasr(monkeypatch, fail_once_for_models=()):
+    remaining_failures = {model: 1 for model in fail_once_for_models}
+
     class DummyAutoModel:
         instances = []
+        attempts = []
 
         def __init__(self, **kwargs):
+            self.__class__.attempts.append(kwargs)
+            model = kwargs.get("model")
+            if remaining_failures.get(model, 0):
+                remaining_failures[model] -= 1
+                raise RuntimeError(f"{model} unavailable")
             self.kwargs = kwargs
             self.__class__.instances.append(kwargs)
 
+        def generate(self, **kwargs):
+            if self.kwargs.get("model") == "fsmn-vad":
+                return [{"value": [[0, 1000]]}]
+            return [{"text": "transcript"}]
+
     funasr_stub = types.ModuleType("funasr")
     funasr_stub.AutoModel = DummyAutoModel
     monkeypatch.setitem(sys.modules, "funasr", funasr_stub)
@@ -64,7 +89,10 @@ def install_dummy_vllm(monkeypatch, raise_on_load=False):
             cls.calls.append(kwargs)
             if raise_on_load:
                 raise RuntimeError("vllm unavailable")
-            return object()
+            return cls()
+
+        def generate(self, inputs, **kwargs):
+            return [{"text": "transcript"} for _ in inputs]
 
     monkeypatch.setitem(sys.modules, "funasr.models", types.ModuleType("funasr.models"))
     monkeypatch.setitem(
@@ -76,6 +104,26 @@ def install_dummy_vllm(monkeypatch, raise_on_load=False):
     return DummyVLLM
 
 
+class DummyUpload:
+    filename = "audio.wav"
+
+    async def read(self):
+        return b"not-a-real-wave-file"
+
+
+def transcribe_nano(app):
+    transcribe = app.routes[("POST", "/v1/audio/transcriptions")]
+    return asyncio.run(
+        transcribe(
+            file=DummyUpload(),
+            model="fun-asr-nano",
+            language=None,
+            response_format="json",
+            spk=False,
+        )
+    )
+
+
 def test_fallback_segments_split_long_fun_asr_server_text(monkeypatch):
     module = load_server_app(monkeypatch)
     text = (
@@ -150,6 +198,52 @@ def test_default_fun_asr_nano_fallback_uses_requested_modelscope_hub(monkeypatch
     assert fallback["hub"] == "ms"
 
 
+def test_fun_asr_nano_reuses_fallback_after_vllm_failure(monkeypatch):
+    module = load_server_app(monkeypatch)
+    DummyAutoModel = install_dummy_funasr(monkeypatch)
+    DummyVLLM = install_dummy_vllm(monkeypatch, raise_on_load=True)
+    monkeypatch.setattr(module.sf, "info", lambda path: types.SimpleNamespace(duration=1.0))
+
+    app = module.create_app(device="cuda", preload_model="fun-asr-nano", hub="ms")
+
+    for _ in range(2):
+        assert transcribe_nano(app) == {"text": "transcript"}
+
+    nano_fallbacks = [
+        config
+        for config in DummyAutoModel.instances
+        if config.get("model") == "FunAudioLLM/Fun-ASR-Nano-2512"
+    ]
+    assert len(DummyVLLM.calls) == 1
+    assert len(nano_fallbacks) == 1
+
+
+def test_partial_vllm_setup_is_not_cached_after_fallback_failure(monkeypatch):
+    module = load_server_app(monkeypatch)
+    nano_model = "FunAudioLLM/Fun-ASR-Nano-2512"
+    DummyAutoModel = install_dummy_funasr(
+        monkeypatch,
+        fail_once_for_models=("fsmn-vad", nano_model),
+    )
+    DummyVLLM = install_dummy_vllm(monkeypatch)
+    monkeypatch.setattr(
+        module.sf,
+        "read",
+        lambda stream: (module.np.ones(16000, dtype=module.np.float32), 16000),
+    )
+
+    app = module.create_app(device="cuda", preload_model="sensevoice", hub="ms")
+
+    with pytest.raises(RuntimeError, match=f"{nano_model} unavailable"):
+        transcribe_nano(app)
+
+    assert app.state.engine is None
+
+    assert transcribe_nano(app) == {"text": "transcript"}
+    assert len(DummyVLLM.calls) == 2
+    assert len([attempt for attempt in DummyAutoModel.attempts if attempt.get("model") == "fsmn-vad"]) == 2
+
+
 def test_custom_model_path_fallback_uses_empty_config_and_requested_hub(monkeypatch):
     module = load_server_app(monkeypatch)
     DummyAutoModel = install_dummy_funasr(monkeypatch)