[misc][core] lazy import outlines (#7831)

.buildkite/test-pipeline.yaml

@@ -87,7 +87,8 @@ steps:
   commands:
   - pip install -e ./plugins/vllm_add_dummy_model
   - pip install git+https://github.com/EleutherAI/lm-evaluation-harness.git@a4987bba6e9e9b3f22bd3a6c1ecf0abd04fd5622#egg=lm_eval[api]
-  - pytest -v -s entrypoints/llm
+  - pytest -v -s entrypoints/llm --ignore=entrypoints/llm/test_lazy_outlines.py
+  - pytest -v -s entrypoints/llm/test_lazy_outlines.py # it needs a clean process
   - pytest -v -s entrypoints/openai
 
 - label: Distributed Tests (4 GPUs) # 10min

tests/entrypoints/llm/test_lazy_outlines.py

+import sys
+
+from vllm import LLM, SamplingParams
+
+
+def test_lazy_outlines(sample_regex):
+    """If users don't use guided decoding, outlines should not be imported.
+    """
+    prompts = [
+        "Hello, my name is",
+        "The president of the United States is",
+        "The capital of France is",
+        "The future of AI is",
+    ]
+    sampling_params = SamplingParams(temperature=0.8, top_p=0.95)
+
+    llm = LLM(model="facebook/opt-125m",
+              enforce_eager=True,
+              gpu_memory_utilization=0.3)
+    outputs = llm.generate(prompts, sampling_params)
+    for output in outputs:
+        prompt = output.prompt
+        generated_text = output.outputs[0].text
+        print(f"Prompt: {prompt!r}, Generated text: {generated_text!r}")
+
+    # make sure outlines is not imported
+    assert 'outlines' not in sys.modules
+
+    llm = LLM(model="facebook/opt-125m",
+              enforce_eager=True,
+              guided_decoding_backend="lm-format-enforcer",
+              gpu_memory_utilization=0.3)
+    sampling_params = SamplingParams(temperature=0.8, top_p=0.95)
+    outputs = llm.generate(
+        prompts=[
+            f"Give an example IPv4 address with this regex: {sample_regex}"
+        ] * 2,
+        sampling_params=sampling_params,
+        use_tqdm=True,
+        guided_options_request=dict(guided_regex=sample_regex))
+
+    for output in outputs:
+        prompt = output.prompt
+        generated_text = output.outputs[0].text
+        print(f"Prompt: {prompt!r}, Generated text: {generated_text!r}")
+
+    # make sure outlines is not imported
+    assert 'outlines' not in sys.modules

vllm/model_executor/guided_decoding/__init__.py

@@ -5,9 +5,6 @@ from vllm.entrypoints.openai.protocol import (
     CompletionRequest)
 from vllm.model_executor.guided_decoding.guided_fields import (
     GuidedDecodingRequest)
-from vllm.model_executor.guided_decoding.outlines_decoding import (
-    get_local_outlines_guided_decoding_logits_processor,
-    get_outlines_guided_decoding_logits_processor)
 from vllm.sampling_params import LogitsProcessor
 
 
@@ -18,6 +15,9 @@ async def get_guided_decoding_logits_processor(
     request = _adapt_request_for_tool_use(request)
 
     if guided_decoding_backend == 'outlines':
+        # NOTE: lazy import outlines to avoid https://github.com/vllm-project/vllm/issues/4193
+        from vllm.model_executor.guided_decoding.outlines_decoding import (  # noqa
+            get_outlines_guided_decoding_logits_processor)
         return await get_outlines_guided_decoding_logits_processor(
             request, tokenizer)
     if guided_decoding_backend == 'lm-format-enforcer':
@@ -37,6 +37,9 @@ def get_local_guided_decoding_logits_processor(
     # request = _adapt_request_for_tool_use(request)
 
     if guided_decoding_backend == 'outlines':
+        # NOTE: lazy import outlines to avoid https://github.com/vllm-project/vllm/issues/4193
+        from vllm.model_executor.guided_decoding.outlines_decoding import (  # noqa
+            get_local_outlines_guided_decoding_logits_processor)
         return get_local_outlines_guided_decoding_logits_processor(
             guided_options, tokenizer)
     if guided_decoding_backend == 'lm-format-enforcer':

vllm/model_executor/guided_decoding/lm_format_enforcer_decoding.py

@@ -14,9 +14,6 @@ from vllm.entrypoints.openai.protocol import (ChatCompletionRequest,
                                               CompletionRequest)
 from vllm.model_executor.guided_decoding.guided_fields import (
     GuidedDecodingRequest)
-from vllm.model_executor.guided_decoding.outlines_decoding import (
-    get_local_outlines_guided_decoding_logits_processor,
-    get_outlines_guided_decoding_logits_processor)
 from vllm.sampling_params import LogitsProcessor
 
 
@@ -43,6 +40,10 @@ async def get_lm_format_enforcer_guided_decoding_logits_processor(
         character_level_parser = RegexParser(request.guided_regex)
     elif request.guided_grammar:
         # CFG grammar not supported by LMFE, revert to outlines
+
+        # NOTE: lazy import outlines to avoid https://github.com/vllm-project/vllm/issues/4193
+        from vllm.model_executor.guided_decoding.outlines_decoding import (
+            get_outlines_guided_decoding_logits_processor)
         return await get_outlines_guided_decoding_logits_processor(
             request, tokenizer)
     elif (request.response_format is not None
@@ -87,6 +88,10 @@ def get_local_lm_format_enforcer_guided_decoding_logits_processor(
         character_level_parser = RegexParser(guided_options.guided_regex)
     elif guided_options.guided_grammar:
         # CFG grammar not supported by LMFE, revert to outlines
+
+        # NOTE: lazy import outlines to avoid https://github.com/vllm-project/vllm/issues/4193
+        from vllm.model_executor.guided_decoding.outlines_decoding import (
+            get_local_outlines_guided_decoding_logits_processor)
         return get_local_outlines_guided_decoding_logits_processor(
             guided_options, tokenizer)
     elif guided_options.guided_json_object: