Support stream=True in v1/completions (#49)

README.md

@@ -238,9 +238,25 @@ curl http://localhost:30000/generate \
     }
   }'
 ```
-
 Learn more about the argument format [here](docs/sampling_params.md).
 
+### OpenAI Compatible API
+
+In addition, the server supports an experimental OpenAI-compatible API.
+
+```python
+import openai
+client = openai.Client(
+    base_url="http://127.0.0.1:30000/v1", api_key="EMPTY")
+response = client.completions.create(
+	model="default",
+	prompt="The capital of France is",
+	temperature=0,
+	max_tokens=32,
+)
+print(response)
+```
+
 ### Additional Arguments
 - Add `--tp 2` to enable tensor parallelism.
 ```

python/pyproject.toml

@@ -19,7 +19,7 @@ dependencies = [
 
 [project.optional-dependencies]
 srt = ["fastapi", "psutil", "rpyc", "torch", "uvloop", "uvicorn", "zmq", "vllm>=0.2.5",
-       "interegular", "lark", "numba"]
+       "interegular", "lark", "numba", "pydantic"]
 openai = ["openai>=1.0"]
 anthropic = ["anthropic"]
 all = ["sglang[srt]", "sglang[openai]", "sglang[anthropic]"]

python/sglang/backend/runtime_endpoint.py

@@ -116,9 +116,12 @@ class RuntimeEndpoint(BaseBackend):
         pos = 0
 
         incomplete_text = ""
-        for chunk in response.iter_lines(decode_unicode=False, delimiter=b"\0"):
-            if chunk:
-                data = json.loads(chunk.decode())
+        for chunk in response.iter_lines(decode_unicode=False):
+            chunk = chunk.decode("utf-8")
+            if chunk and chunk.startswith("data:"):
+                if chunk == "data: [DONE]":
+                    break
+                data = json.loads(chunk[5:].strip("\n"))
                 text = find_printable_text(data["text"][pos:])
                 meta_info = data["meta_info"]
                 pos += len(text)

python/sglang/srt/managers/openai_protocol.py

-from dataclasses import dataclass
-from typing import Any, List, Optional, Union
+import time
+from typing import Dict, List, Optional, Union
 
+from pydantic import BaseModel, Field
 
-@dataclass
-class CompletionRequest:
-    prompt: Union[str, List[Any]]
-    model: str = "default"
-    temperature: Optional[float] = 0.7
+
+class LogProbs(BaseModel):
+    text_offset: List[int] = Field(default_factory=list)
+    token_logprobs: List[Optional[float]] = Field(default_factory=list)
+    tokens: List[str] = Field(default_factory=list)
+    top_logprobs: List[Optional[Dict[str, float]]] = Field(default_factory=list)
+
+
+class UsageInfo(BaseModel):
+    prompt_tokens: int = 0
+    total_tokens: int = 0
+    completion_tokens: Optional[int] = 0
+
+
+class CompletionRequest(BaseModel):
+    model: str
+    prompt: Union[str, List[str]]
+    suffix: Optional[str] = None
     max_tokens: Optional[int] = 16
+    temperature: Optional[float] = 0.7
+    top_p: Optional[float] = 1.0
     n: Optional[int] = 1
-    stop: Optional[Union[str, List[str]]] = None
+    stream: Optional[bool] = False
+    logprobs: Optional[int] = None
+    echo: Optional[bool] = False
+    stop: Optional[Union[str, List[str]]] = Field(default_factory=list)
+    presence_penalty: Optional[float] = 0.0
+    frequency_penalty: Optional[float] = 0.0
+    best_of: Optional[int] = None
+    logit_bias: Optional[Dict[str, float]] = None
+    user: Optional[str] = None
+
+
+class CompletionResponseChoice(BaseModel):
+    index: int
+    text: str
+    logprobs: Optional[LogProbs] = None
+    finish_reason: Optional[str] = None
+
+
+class CompletionResponse(BaseModel):
+    id: str
+    object: str = "text_completion"
+    created: int = Field(default_factory=lambda: int(time.time()))
+    model: str
+    choices: List[CompletionResponseChoice]
+    usage: UsageInfo
+
+
+class CompletionResponseStreamChoice(BaseModel):
+    index: int
+    text: str
+    logprobs: Optional[LogProbs] = None
+    finish_reason: Optional[str] = None
+
+
+class CompletionStreamResponse(BaseModel):
+    id: str
+    object: str = "text_completion"
+    created: int = Field(default_factory=lambda: int(time.time()))
+    model: str
+    choices: List[CompletionResponseStreamChoice]

python/sglang/srt/server.py

 """SRT: SGLang Runtime"""
-import argparse
 import asyncio
-import dataclasses
 import json
 import multiprocessing as mp
 import sys
@@ -16,12 +14,19 @@ import psutil
 import requests
 import uvicorn
 import uvloop
-from fastapi import FastAPI
+from fastapi import FastAPI, Request
 from fastapi.responses import StreamingResponse
 from sglang.backend.runtime_endpoint import RuntimeEndpoint
 from sglang.srt.managers.detokenizer_manager import start_detokenizer_process
 from sglang.srt.managers.io_struct import GenerateReqInput
-from sglang.srt.managers.openai_protocol import CompletionRequest
+from sglang.srt.managers.openai_protocol import (
+    CompletionRequest,
+    CompletionResponse,
+    CompletionResponseChoice,
+    CompletionResponseStreamChoice,
+    CompletionStreamResponse,
+    UsageInfo
+)
 from sglang.srt.managers.router.manager import start_router_process
 from sglang.srt.managers.tokenizer_manager import TokenizerManager
 from sglang.srt.server_args import PortArgs, ServerArgs
@@ -41,39 +46,97 @@ async def get_model_info():
     }
     return result
 
+async def stream_generator(obj):
+    async for out in tokenizer_manager.generate_request(obj):
+        yield out
+
 
 @app.post("/generate")
 async def generate_request(obj: GenerateReqInput):
     obj.post_init()
-    result_generator = tokenizer_manager.generate_request(obj)
 
     if obj.stream:
 
         async def stream_results():
-            async for out in result_generator:
-                yield (json.dumps(out) + "\0").encode("utf-8")
+            async for out in stream_generator(obj):
+                yield f"data: {json.dumps(out, ensure_ascii=False)}\n\n"
+            yield "data: [DONE]\n\n"
         
         return StreamingResponse(stream_results(), media_type="text/event-stream")
-    else:
-        ret = await result_generator.__anext__()
+
+    ret = await tokenizer_manager.generate_request(obj).__anext__()
     return ret
 
 
 @app.post("/v1/completions")
-async def v1_completions(obj: CompletionRequest):
-    assert obj.n == 1
-    obj = GenerateReqInput(
-        text=obj.prompt,
+async def v1_completions(raw_request: Request):
+    request_json = await raw_request.json()
+    request = CompletionRequest(**request_json)
+
+    # TODO: Validate the request and return HTTPStatus.BAD_REQUEST if invalid.
+    assert request.n == 1
+
+    adapted_request = GenerateReqInput(
+        text=request.prompt,
         sampling_params={
-            "temperature": obj.temperature,
-            "max_new_tokens": obj.max_tokens,
-            "stop": obj.stop,
+            "temperature": request.temperature,
+            "max_new_tokens": request.max_tokens,
+            "stop": request.stop,
+            "top_p": request.top_p,
+            "presence_penalty": request.presence_penalty,
+            "frequency_penalty": request.frequency_penalty,
         },
+        stream=request.stream,
     )
-    ret = await generate_request(obj)
-    return {
-        "choices": [{"text": ret["text"]}],
-    }
+    adapted_request.post_init()
+
+    if adapted_request.stream:
+        async def gnerate_stream_resp():
+            stream_buffer = ""
+            async for content in stream_generator(adapted_request):
+                text = content["text"]
+                delta = text[len(stream_buffer):]
+                stream_buffer = text
+                choice_data = CompletionResponseStreamChoice(
+                    index=0,
+                    text=delta,
+                    logprobs=None,
+                    finish_reason=None,
+                )
+                chunk = CompletionStreamResponse(
+                    id=content["meta_info"]["id"],
+                    object="text_completion",
+                    choices=[choice_data],
+                    model=request.model,
+                )
+                yield f"data: {chunk.json(exclude_unset=True, ensure_ascii=False)}\n\n"
+
+        return StreamingResponse(gnerate_stream_resp(), media_type="text/event-stream")
+
+
+    # Non-streaming response.
+    ret = await generate_request(adapted_request)
+
+    choice_data = CompletionResponseChoice(
+        index=0,
+        text=ret["text"],
+        logprobs=None,
+        finish_reason=None, # TODO(comaniac): Add finish reason.
+    )
+
+    prompt_tokens = ret["meta_info"]["prompt_tokens"]
+    completion_tokens = ret["meta_info"]["completion_tokens"]
+    response = CompletionResponse(
+        id=ret["meta_info"]["id"],
+        model=request.model,
+        choices=[choice_data],
+        usage=UsageInfo(
+            prompt_tokens=prompt_tokens,
+            completion_tokens=completion_tokens,
+            total_tokens=prompt_tokens + completion_tokens,
+        ),
+    )
+    return response
 
 
 def launch_server(server_args, pipe_finish_writer):

test/srt/test_httpserver_decode_stream.py

@@ -25,7 +25,7 @@ if __name__ == "__main__":
             "text": "The capital of France is",
             "sampling_params": {
                 "temperature": 0,
-                "max_new_tokens": 1024,
+                "max_new_tokens": 512,
             },
             "stream": True,
         },
@@ -33,9 +33,12 @@ if __name__ == "__main__":
     )
 
     prev = 0
-    for chunk in response.iter_lines(decode_unicode=False, delimiter=b"\0"):
-        if chunk:
-            data = json.loads(chunk.decode())
+    for chunk in response.iter_lines(decode_unicode=False):
+        chunk = chunk.decode("utf-8")
+        if chunk and chunk.startswith("data:"):
+            if chunk == "data: [DONE]":
+                break
+            data = json.loads(chunk[5:].strip("\n"))
             output = data["text"].strip()
             print(output[prev:], end="", flush=True)
             prev = len(output)

test/srt/test_openai_server.py

+"""
+python3 -m sglang.launch_server --model-path TinyLlama/TinyLlama-1.1B-Chat-v0.4 --port 30000
+
+Output:
+The capital of France is Paris.\nThe capital of the United States is Washington, D.C.\nThe capital of Canada is Ottawa.\nThe capital of Japan is Tokyo
+"""
+
+import argparse
+
+import openai
+
+
+def test_completion(args):
+    client = openai.Client(api_key="EMPTY", base_url=args.base_url)
+    response = client.completions.create(
+        model="default",
+        prompt="The capital of France is",
+        temperature=0,
+        max_tokens=32,
+    )
+    print(response.choices[0].text)
+    assert response.id
+    assert response.created
+    assert response.usage.prompt_tokens > 0
+    assert response.usage.completion_tokens > 0
+    assert response.usage.total_tokens > 0
+
+
+def test_completion_stream(args):
+    client = openai.Client(api_key="EMPTY", base_url=args.base_url)
+    response = client.completions.create(
+        model="default",
+        prompt="The capital of France is",
+        temperature=0,
+        max_tokens=32,
+        stream=True,
+    )
+    for r in response:
+        print(r.choices[0].text, end="", flush=True)
+        assert r.id
+        assert r.created
+        assert r.usage.prompt_tokens > 0
+        assert r.usage.completion_tokens > 0
+        assert r.usage.total_tokens > 0
+    print()
+
+
+if __name__ == "__main__":
+    parser = argparse.ArgumentParser()
+    parser.add_argument("--base-url", type=str, default="http://127.0.0.1:30000/v1")
+    args = parser.parse_args()
+
+    test_completion(args)
+    test_completion_stream(args)