[V1] Make v1 more testable

Dockerfile

@@ -191,6 +191,9 @@ ADD . /vllm-workspace/
 RUN --mount=type=cache,target=/root/.cache/pip \
     python3 -m pip install -r requirements-dev.txt
 
+# Copy in the v1 package for testing (it isn't distributed yet)
+COPY vllm/v1 /usr/local/lib/python3.12/dist-packages/vllm/v1
+
 # doc requires source code
 # we hide them inside `test_docs/` , so that this source code
 # will not be imported by other tests

pyproject.toml

@@ -97,4 +97,5 @@ markers = [
     "skip_global_cleanup",
     "core_model: run this model test in each PR instead of just daily",
     "distributed_2_gpus: run this test only in distributed tests for 2 GPUs",
+    "skip_v1: do not run this test with v1",
 ]

tests/conftest.py

@@ -6,6 +6,7 @@
 from enum import Enum
 from typing import (Any, Callable, Dict, List, Optional, Tuple, Type,
                     TypedDict, TypeVar, Union)
+from unittest.mock import patch
 
 import numpy as np
 import pytest
@@ -121,6 +122,23 @@ def prompts(self, prompts: _VideoAssetPrompts) -> List[str]:
 """Singleton instance of :class:`_VideoAssets`."""
 
 
+@pytest.fixture(params=[True, False])
+def run_with_both_engines(request):
+    # Automatically runs tests twice, once with V1 and once without
+    use_v1 = request.param
+    # Tests decorated with `@skip_v1` are only run without v1
+    skip_v1 = request.node.get_closest_marker("skip_v1")
+
+    if use_v1:
+        if skip_v1:
+            pytest.skip("Skipping test on vllm V1")
+        with patch('vllm.envs.VLLM_USE_V1', True):
+            yield
+    else:
+        with patch('vllm.envs.VLLM_USE_V1', False):
+            yield
+
+
 @pytest.fixture(autouse=True)
 def init_test_http_connection():
     # pytest_asyncio may use a different event loop per test

tests/entrypoints/llm/test_prompt_validation.py

@@ -3,12 +3,21 @@
 from vllm import LLM
 
 
+@pytest.fixture(autouse=True)
+def v1(run_with_both_engines):
+    # Simple autouse wrapper to run both engines for each test
+    # This can be promoted up to conftest.py to run for every
+    # test in a package
+    pass
+
+
 def test_empty_prompt():
     llm = LLM(model="gpt2", enforce_eager=True)
     with pytest.raises(ValueError, match='Prompt cannot be empty'):
         llm.generate([""])
 
 
+@pytest.mark.skip_v1
 def test_out_of_vocab_token():
     llm = LLM(model="gpt2", enforce_eager=True)
     with pytest.raises(ValueError, match='out of vocabulary'):

vllm/attention/selector.py

@@ -88,7 +88,6 @@ def get_global_forced_attn_backend() -> Optional[_Backend]:
     return forced_attn_backend
 
 
-@lru_cache(maxsize=None)
 def get_attn_backend(
     head_size: int,
     dtype: torch.dtype,
@@ -98,14 +97,39 @@ def get_attn_backend(
     is_blocksparse: bool = False,
 ) -> Type[AttentionBackend]:
     """Selects which attention backend to use and lazily imports it."""
+    # Accessing envs.* behind an @lru_cache decorator can cause the wrong
+    # value to be returned from the cache if the value changes between calls.
+    # To avoid this, we read envs.VLLM_USE_V1 here and pass it explicitly to the
+    # private function.
+    return _cached_get_attn_backend(
+        head_size=head_size,
+        dtype=dtype,
+        kv_cache_dtype=kv_cache_dtype,
+        block_size=block_size,
+        is_attention_free=is_attention_free,
+        is_blocksparse=is_blocksparse,
+        use_v1=envs.VLLM_USE_V1,
+    )
+
+
+@lru_cache(maxsize=None)
+def _cached_get_attn_backend(
+    head_size: int,
+    dtype: torch.dtype,
+    kv_cache_dtype: Optional[str],
+    block_size: int,
+    is_attention_free: bool,
+    is_blocksparse: bool = False,
+    use_v1: bool = False,
+) -> Type[AttentionBackend]:
     if is_blocksparse:
         logger.info("Using BlocksparseFlashAttention backend.")
         from vllm.attention.backends.blocksparse_attn import (
             BlocksparseFlashAttentionBackend)
         return BlocksparseFlashAttentionBackend
 
     backend = which_attn_to_use(head_size, dtype, kv_cache_dtype, block_size,
-                                is_attention_free)
+                                is_attention_free, use_v1)
     if backend == _Backend.FLASH_ATTN:
         logger.info("Using Flash Attention backend.")
         from vllm.attention.backends.flash_attn import (  # noqa: F401
@@ -157,13 +181,9 @@ def get_attn_backend(
         raise ValueError("Invalid attention backend.")
 
 
-def which_attn_to_use(
-    head_size: int,
-    dtype: torch.dtype,
-    kv_cache_dtype: Optional[str],
-    block_size: int,
-    is_attention_free: bool,
-) -> _Backend:
+def which_attn_to_use(head_size: int, dtype: torch.dtype,
+                      kv_cache_dtype: Optional[str], block_size: int,
+                      is_attention_free: bool, use_v1: bool) -> _Backend:
     """Returns which flash attention backend to use."""
     # Default case.
     selected_backend = _Backend.FLASH_ATTN
@@ -220,7 +240,7 @@ def which_attn_to_use(
             logger.info("%s is not supported in AMD GPUs.", selected_backend)
         return _Backend.ROCM_FLASH
 
-    if envs.VLLM_USE_V1:
+    if use_v1:
         return _Backend.FLASH_ATTN_VLLM_V1
 
     # FlashAttn in NVIDIA GPUs.

vllm/engine/multiprocessing/engine.py

@@ -7,7 +7,9 @@
 import zmq
 from ray.exceptions import RayTaskError
 
+import vllm.envs
 from vllm import AsyncEngineArgs, SamplingParams
+from vllm.engine.llm_engine import LLMEngine
 # yapf conflicts with isort for this block
 # yapf: disable
 from vllm.engine.multiprocessing import (ENGINE_DEAD_ERROR, IPC_DATA_EXT,
@@ -18,17 +20,11 @@
                                          RPCStartupRequest, RPCStartupResponse,
                                          RPCUProfileRequest)
 # yapf: enable
-from vllm.envs import VLLM_USE_V1
 from vllm.executor.gpu_executor import GPUExecutor
 from vllm.logger import init_logger
 from vllm.outputs import RequestOutput
 from vllm.usage.usage_lib import UsageContext
 
-if VLLM_USE_V1:
-    from vllm.v1.engine.llm_engine import LLMEngine
-else:
-    from vllm.engine.llm_engine import LLMEngine
-
 logger = init_logger(__name__)
 
 POLLING_TIMEOUT_MS = 10000
@@ -118,11 +114,17 @@ def from_engine_args(cls, engine_args: AsyncEngineArgs,
         load_general_plugins()
 
         engine_config = engine_args.create_engine_config()
+        if vllm.envs.VLLM_USE_V1:
+            # Lazy import: the v1 package isn't distributed
+            from vllm.v1.engine.llm_engine import LLMEngine as V1LLMEngine
+            engine_class = V1LLMEngine
+        else:
+            engine_class = LLMEngine
 
-        executor_class = LLMEngine._get_executor_cls(engine_config)
+        executor_class = engine_class._get_executor_cls(engine_config)
 
         use_async_sockets = (engine_config.model_config.use_async_output_proc
-                             and not VLLM_USE_V1)
+                             and not vllm.envs.VLLM_USE_V1)
 
         return cls(ipc_path=ipc_path,
                    use_async_sockets=use_async_sockets,

vllm/entrypoints/llm.py

@@ -1,7 +1,7 @@
 import itertools
 import warnings
 from contextlib import contextmanager
-from typing import (Any, ClassVar, Dict, List, Optional, Sequence, Tuple,
+from typing import (Any, ClassVar, Dict, List, Optional, Sequence, Tuple, Type,
                     Union, cast, overload)
 
 from tqdm import tqdm
@@ -10,6 +10,7 @@
 from vllm.beam_search import (BeamSearchInstance, BeamSearchOutput,
                               BeamSearchSequence, get_beam_search_score)
 from vllm.engine.arg_utils import EngineArgs, TaskOption
+from vllm.engine.llm_engine import LLMEngine
 from vllm.entrypoints.chat_utils import (ChatCompletionMessageParam,
                                          apply_hf_chat_template,
                                          apply_mistral_chat_template,
@@ -31,11 +32,6 @@
 from vllm.usage.usage_lib import UsageContext
 from vllm.utils import Counter, deprecate_args, deprecate_kwargs, is_list_of
 
-if envs.VLLM_USE_V1:
-    from vllm.v1.engine.llm_engine import LLMEngine  # type: ignore
-else:
-    from vllm.engine.llm_engine import LLMEngine  # type: ignore
-
 logger = init_logger(__name__)
 
 
@@ -206,10 +202,21 @@ def __init__(
             pooling_returned_token_ids=pooling_returned_token_ids,
             **kwargs,
         )
-        self.llm_engine = LLMEngine.from_engine_args(
+        # Logic to switch between engines is done at runtime instead of import
+        # to avoid import order issues
+        self.engine_class = self.get_engine_class()
+        self.llm_engine = self.engine_class.from_engine_args(
             engine_args, usage_context=UsageContext.LLM_CLASS)
         self.request_counter = Counter()
 
+    @staticmethod
+    def get_engine_class() -> Type[LLMEngine]:
+        if envs.VLLM_USE_V1:
+            # Lazy import: the v1 package isn't distributed
+            from vllm.v1.engine.llm_engine import LLMEngine as V1LLMEngine
+            return V1LLMEngine  # type: ignore
+        return LLMEngine
+
     def get_tokenizer(self) -> AnyTokenizer:
         return self.llm_engine.get_tokenizer_group(TokenizerGroup).tokenizer
 
@@ -394,7 +401,7 @@ def generate(
             priority=priority)
 
         outputs = self._run_engine(use_tqdm=use_tqdm)
-        return LLMEngine.validate_outputs(outputs, RequestOutput)
+        return self.engine_class.validate_outputs(outputs, RequestOutput)
 
     def beam_search(
         self,
@@ -769,7 +776,8 @@ def encode(
         )
 
         outputs = self._run_engine(use_tqdm=use_tqdm)
-        return LLMEngine.validate_outputs(outputs, EmbeddingRequestOutput)
+        return self.engine_class.validate_outputs(outputs,
+                                                  EmbeddingRequestOutput)
 
     def start_profile(self) -> None:
         self.llm_engine.start_profile()

vllm/model_executor/layers/sampler.py

@@ -30,6 +30,15 @@
 else:
     flashinfer_top_k_top_p_sampling = None
 
+
+def get_sampler() -> torch.nn.Module:
+    if envs.VLLM_USE_V1:
+        # Lazy import: the v1 package isn't distributed
+        from vllm.v1.sample.sampler import Sampler as V1Sampler
+        return V1Sampler()
+    return Sampler()
+
+
 # (num_token_ids, num_parent_ids) per sequence group.
 SampleResultType = List[Tuple[List[int], List[int]]]
 

vllm/model_executor/models/arctic.py

@@ -23,7 +23,7 @@
 from vllm.model_executor.layers.quantization.deepspeedfp import (
     DeepSpeedFPConfig, DeepSpeedFPParameter)
 from vllm.model_executor.layers.rotary_embedding import get_rope
-from vllm.model_executor.layers.sampler import Sampler, SamplerOutput
+from vllm.model_executor.layers.sampler import SamplerOutput, get_sampler
 from vllm.model_executor.layers.vocab_parallel_embedding import (
     ParallelLMHead, VocabParallelEmbedding)
 from vllm.model_executor.model_loader.weight_utils import default_weight_loader
@@ -436,7 +436,7 @@ def __init__(self,
         self.unpadded_vocab_size = config.vocab_size
         self.logits_processor = LogitsProcessor(self.unpadded_vocab_size,
                                                 config.vocab_size)
-        self.sampler = Sampler()
+        self.sampler = get_sampler()
         self.make_empty_intermediate_tensors = (
             self.model.make_empty_intermediate_tensors)
 

vllm/model_executor/models/baichuan.py

@@ -38,7 +38,7 @@
 from vllm.model_executor.layers.logits_processor import LogitsProcessor
 from vllm.model_executor.layers.quantization import QuantizationConfig
 from vllm.model_executor.layers.rotary_embedding import get_rope
-from vllm.model_executor.layers.sampler import Sampler, SamplerOutput
+from vllm.model_executor.layers.sampler import SamplerOutput, get_sampler
 from vllm.model_executor.layers.vocab_parallel_embedding import (
     ParallelLMHead, VocabParallelEmbedding)
 from vllm.model_executor.model_loader.weight_utils import default_weight_loader
@@ -353,7 +353,7 @@ def __init__(
         if self.config.tie_word_embeddings:
             self.lm_head.weight = self.model.embed_tokens.weight
         self.logits_processor = LogitsProcessor(config.vocab_size)
-        self.sampler = Sampler()
+        self.sampler = get_sampler()
         self.make_empty_intermediate_tensors = (
             self.model.make_empty_intermediate_tensors)
 

vllm/model_executor/models/bart.py

@@ -34,7 +34,7 @@
 from vllm.model_executor.layers.logits_processor import LogitsProcessor
 from vllm.model_executor.layers.quantization.base_config import (
     QuantizationConfig)
-from vllm.model_executor.layers.sampler import Sampler, SamplerOutput
+from vllm.model_executor.layers.sampler import SamplerOutput, get_sampler
 from vllm.model_executor.layers.vocab_parallel_embedding import (
     ParallelLMHead, VocabParallelEmbedding)
 from vllm.model_executor.model_loader.weight_utils import default_weight_loader
@@ -840,7 +840,7 @@ def __init__(self,
 
         self.logits_processor = LogitsProcessor(self.unpadded_vocab_size,
                                                 config.vocab_size)
-        self.sampler = Sampler()
+        self.sampler = get_sampler()
 
     def forward(
         self,

vllm/model_executor/models/blip2.py

@@ -13,7 +13,7 @@
                          InputContext, token_inputs)
 from vllm.model_executor.layers.activation import get_act_fn
 from vllm.model_executor.layers.quantization import QuantizationConfig
-from vllm.model_executor.layers.sampler import Sampler, SamplerOutput
+from vllm.model_executor.layers.sampler import SamplerOutput, get_sampler
 from vllm.model_executor.sampling_metadata import SamplingMetadata
 from vllm.multimodal import MULTIMODAL_REGISTRY
 from vllm.multimodal.utils import consecutive_placeholder_ranges
@@ -525,7 +525,7 @@ def sampler(self):
         if hasattr(self.language_model, "sampler"):
             return self.language_model.sampler
 
-        return Sampler()
+        return get_sampler()
 
     def _validate_pixel_values(self, data: torch.Tensor) -> torch.Tensor:
         h = w = self.config.vision_config.image_size

vllm/model_executor/models/bloom.py

@@ -34,7 +34,7 @@
                                                RowParallelLinear)
 from vllm.model_executor.layers.logits_processor import LogitsProcessor
 from vllm.model_executor.layers.quantization import QuantizationConfig
-from vllm.model_executor.layers.sampler import Sampler, SamplerOutput
+from vllm.model_executor.layers.sampler import SamplerOutput, get_sampler
 from vllm.model_executor.layers.vocab_parallel_embedding import (
     ParallelLMHead, VocabParallelEmbedding)
 from vllm.model_executor.model_loader.weight_utils import default_weight_loader
@@ -299,7 +299,7 @@ def __init__(
                                           self.config.hidden_size)
 
         self.logits_processor = LogitsProcessor(config.vocab_size)
-        self.sampler = Sampler()
+        self.sampler = get_sampler()
         self.make_empty_intermediate_tensors = (
             self.transformer.make_empty_intermediate_tensors)
 

vllm/model_executor/models/chameleon.py

@@ -21,7 +21,7 @@
 from vllm.model_executor.layers.logits_processor import LogitsProcessor
 from vllm.model_executor.layers.quantization import QuantizationConfig
 from vllm.model_executor.layers.rotary_embedding import get_rope
-from vllm.model_executor.layers.sampler import Sampler, SamplerOutput
+from vllm.model_executor.layers.sampler import SamplerOutput, get_sampler
 from vllm.model_executor.layers.vocab_parallel_embedding import (
     ParallelLMHead, VocabParallelEmbedding)
 from vllm.model_executor.model_loader.weight_utils import (
@@ -946,7 +946,7 @@ def __init__(
         logit_scale = getattr(config, "logit_scale", 1.0)
         self.logits_processor = LogitsProcessor(self.unpadded_vocab_size,
                                                 config.vocab_size, logit_scale)
-        self.sampler = Sampler()
+        self.sampler = get_sampler()
         self.make_empty_intermediate_tensors = (
             self.model.make_empty_intermediate_tensors)