Add an async example (#37)

examples/usage/async.py

+import asyncio
+from sglang import Runtime
+
+
+async def generate(
+    engine,
+    prompt,
+    sampling_params,
+):
+    tokenizer = engine.get_tokenizer()
+
+    messages = [
+        {"role": "system", "content": "You will be given question answer tasks.",},
+        {"role": "user", "content": prompt},
+    ]
+
+    prompt = tokenizer.apply_chat_template(
+        messages, tokenize=False, add_generation_prompt=True
+    )
+
+    stream = engine.add_request(prompt, sampling_params)
+
+    async for output in stream:
+        print(output, end="", flush=True)
+    print()
+
+
+if __name__ == "__main__":
+    runtime = Runtime(model_path="meta-llama/Llama-2-7b-chat-hf")
+    print("runtime ready")
+    
+    prompt = "Who is Alan Turing?"
+    sampling_params = {"max_new_tokens": 128}
+    asyncio.run(generate(runtime, prompt, sampling_params))
+    
+    runtime.shutdown()

python/sglang/backend/openai.py

@@ -78,8 +78,10 @@ class OpenAI(BaseBackend):
         if sampling_params.dtype is None:
             if self.is_chat_model:
                 if not s.text_.endswith("ASSISTANT:"):
-                    raise RuntimeError("This use case is not supported. "
-                        "For OpenAI chat models, sgl.gen must be right after sgl.assistant")
+                    raise RuntimeError(
+                        "This use case is not supported. "
+                        "For OpenAI chat models, sgl.gen must be right after sgl.assistant"
+                    )
                 prompt = s.messages_
             else:
                 prompt = s.text_

python/sglang/srt/server.py

@@ -11,6 +11,7 @@ from typing import List, Optional
 # Fix a Python bug
 setattr(threading, "_register_atexit", lambda *args, **kwargs: None)
 
+import aiohttp
 import psutil
 import requests
 import uvicorn
@@ -25,6 +26,7 @@ from sglang.srt.conversation import (
     generate_chat_conv,
     register_conv_template,
 )
+from sglang.srt.hf_transformers_utils import get_tokenizer
 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 (
@@ -402,7 +404,7 @@ class Runtime:
     ):
         host = "127.0.0.1"
         port = alloc_usable_network_port(1)[0]
-        server_args = ServerArgs(
+        self.server_args = ServerArgs(
             model_path=model_path,
             tokenizer_path=tokenizer_path,
             host=host,
@@ -417,11 +419,14 @@ class Runtime:
             random_seed=random_seed,
             log_level=log_level,
         )
-        self.url = server_args.url()
+        self.url = self.server_args.url()
+        self.generate_url = (
+            f"http://{self.server_args.host}:{self.server_args.port}/generate"
+        )
 
         self.pid = None
         pipe_reader, pipe_writer = mp.Pipe(duplex=False)
-        proc = mp.Process(target=launch_server, args=(server_args, pipe_writer))
+        proc = mp.Process(target=launch_server, args=(self.server_args, pipe_writer))
         proc.start()
         self.pid = proc.pid
 
@@ -443,5 +448,40 @@ class Runtime:
             parent.wait(timeout=5)
             self.pid = None
 
+    def get_tokenizer(self):
+        return get_tokenizer(
+            self.server_args.tokenizer_path,
+            tokenizer_mode=self.server_args.tokenizer_mode,
+            trust_remote_code=self.server_args.trust_remote_code,
+        )
+
+    async def add_request(
+        self,
+        prompt: str,
+        sampling_params,
+    ) -> None:
+
+        json_data = {
+            "text": prompt,
+            "sampling_params": sampling_params,
+            "stream": True,
+        }
+
+        pos = 0
+
+        timeout = aiohttp.ClientTimeout(total=3 * 3600)
+        async with aiohttp.ClientSession(timeout=timeout, trust_env=True) as session:
+            async with session.post(self.generate_url, json=json_data) as response:
+                async for chunk, _ in response.content.iter_chunks():
+                    chunk = chunk.decode("utf-8")
+                    if chunk and chunk.startswith("data:"):
+                        if chunk == "data: [DONE]\n\n":
+                            break
+                        data = json.loads(chunk[5:].strip("\n"))
+                        cur = data["text"][pos:]
+                        if cur:
+                            yield cur
+                        pos += len(cur)
+
     def __del__(self):
         self.shutdown()