446 lines
15 KiB
Python
446 lines
15 KiB
Python
"""
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Minimal HTTP load balancer for prefill and decode servers for testing.
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"""
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import asyncio
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import dataclasses
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import logging
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import random
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import urllib
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from http import HTTPStatus
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from itertools import chain
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from typing import List, Optional
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import aiohttp
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import orjson
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import uvicorn
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from fastapi import FastAPI, HTTPException
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from fastapi.responses import ORJSONResponse, Response, StreamingResponse
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from sglang.srt.disaggregation.utils import PDRegistryRequest
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from sglang.srt.utils import maybe_wrap_ipv6_address
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AIOHTTP_STREAM_READ_CHUNK_SIZE = (
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1024 * 64
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) # 64KB, to prevent aiohttp's "Chunk too big" error
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def setup_logger():
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logger = logging.getLogger("pdlb")
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logger.setLevel(logging.INFO)
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formatter = logging.Formatter(
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"[PDLB (Python)] %(asctime)s - %(levelname)s - %(message)s",
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datefmt="%Y-%m-%d %H:%M:%S",
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)
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handler = logging.StreamHandler()
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handler.setFormatter(formatter)
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logger.addHandler(handler)
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return logger
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logger = setup_logger()
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@dataclasses.dataclass
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class PrefillConfig:
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url: str
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bootstrap_port: Optional[int] = None
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class MiniLoadBalancer:
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def __init__(
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self,
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prefill_configs: List[PrefillConfig],
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decode_servers: List[str],
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timeout: int,
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):
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self.prefill_configs = prefill_configs
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self.prefill_servers = [p.url for p in prefill_configs]
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self.decode_servers = decode_servers
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self.timeout = timeout
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def add_prefill_server(self, new_prefill_config: PrefillConfig):
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self.prefill_configs.append(new_prefill_config)
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self.prefill_servers.append(new_prefill_config.url)
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def add_decode_server(self, new_decode_server: str):
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self.decode_servers.append(new_decode_server)
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def select_pair(self):
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# TODO: return some message instead of panic
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assert len(self.prefill_configs) > 0, "No prefill servers available"
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assert len(self.decode_servers) > 0, "No decode servers available"
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prefill_config = random.choice(self.prefill_configs)
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decode_server = random.choice(self.decode_servers)
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return prefill_config.url, prefill_config.bootstrap_port, decode_server
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async def generate(
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self, modified_request, prefill_server, decode_server, endpoint
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) -> ORJSONResponse:
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assert endpoint[0] != "/", f"Endpoint should not start with '/': {endpoint}"
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async with aiohttp.ClientSession(
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timeout=aiohttp.ClientTimeout(
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total=self.timeout
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) # Add timeout for request reliability
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) as session:
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tasks = [
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session.post(f"{prefill_server}/{endpoint}", json=modified_request),
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session.post(f"{decode_server}/{endpoint}", json=modified_request),
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]
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# Wait for both responses to complete. Prefill should end first.
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prefill_response, decode_response = await asyncio.gather(*tasks)
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if "return_logprob" in modified_request:
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prefill_json = await prefill_response.json()
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ret_json = await decode_response.json()
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# merge `meta_info.input_token_logprobs` from prefill to decode
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if "meta_info" in ret_json:
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if "input_token_logprobs" in ret_json["meta_info"]:
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ret_json["meta_info"]["input_token_logprobs"] = (
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prefill_json["meta_info"]["input_token_logprobs"]
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+ ret_json["meta_info"]["input_token_logprobs"]
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)
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else:
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ret_json = await decode_response.json()
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return ORJSONResponse(
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content=ret_json,
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status_code=decode_response.status,
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)
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async def generate_stream(
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self, modified_request, prefill_server, decode_server, endpoint="generate"
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):
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assert endpoint[0] != "/", f"Endpoint should not start with '/': {endpoint}"
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async def stream_results():
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async with aiohttp.ClientSession(
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timeout=aiohttp.ClientTimeout(
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total=self.timeout
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) # Add timeout for request reliability
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) as session:
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# Create the tasks for both prefill and decode requests
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tasks = [
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session.post(f"{prefill_server}/{endpoint}", json=modified_request),
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session.post(f"{decode_server}/{endpoint}", json=modified_request),
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]
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# Wait for both responses to complete. Since this is streaming, they return immediately.
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prefill_response, decode_response = await asyncio.gather(*tasks)
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if modified_request.get("return_logprob", False):
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prefill_chunks = []
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async for chunk in prefill_response.content:
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prefill_chunks.append(chunk)
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first_prefill_chunk = (
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prefill_chunks[0].decode("utf-8")[5:].strip("\n")
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)
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first_prefill_chunk_json = orjson.loads(first_prefill_chunk)
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async for chunk in decode_response.content:
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# Note: This is inefficient
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# merge prefill input_token_logprobs, output_token_logprobs to decode
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decoded_chunk = chunk.decode("utf-8")
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if (
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decoded_chunk
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and decoded_chunk.startswith("data:")
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and "[DONE]" not in decoded_chunk
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):
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ret_json = orjson.loads(decoded_chunk[5:].strip("\n"))
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ret_json["meta_info"]["input_token_logprobs"] = (
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first_prefill_chunk_json["meta_info"][
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"input_token_logprobs"
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]
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+ ret_json["meta_info"]["input_token_logprobs"]
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)
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yield b"data: " + orjson.dumps(ret_json) + b"\n\n"
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else:
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yield chunk
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else:
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async for chunk in decode_response.content.iter_chunked(
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AIOHTTP_STREAM_READ_CHUNK_SIZE
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):
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yield chunk
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return StreamingResponse(
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stream_results(),
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media_type="text/event-stream",
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)
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app = FastAPI()
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load_balancer: Optional[MiniLoadBalancer] = None
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@app.get("/health")
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async def health_check():
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return Response(status_code=200)
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@app.get("/health_generate")
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async def health_generate():
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prefill_servers, decode_servers = (
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load_balancer.prefill_servers,
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load_balancer.decode_servers,
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)
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async with aiohttp.ClientSession() as session:
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# Create the tasks
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tasks = []
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for server in chain(prefill_servers, decode_servers):
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tasks.append(session.get(f"{server}/health_generate"))
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for i, response in enumerate(asyncio.as_completed(tasks)):
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await response
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return Response(status_code=200)
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@app.post("/flush_cache")
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async def flush_cache():
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prefill_servers, decode_servers = (
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load_balancer.prefill_servers,
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load_balancer.decode_servers,
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)
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async with aiohttp.ClientSession() as session:
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# Create the tasks
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tasks = []
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for server in chain(prefill_servers, decode_servers):
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tasks.append(session.post(f"{server}/flush_cache"))
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for i, response in enumerate(asyncio.as_completed(tasks)):
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await response
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return Response(status_code=200)
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@app.get("/get_server_info")
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async def get_server_info():
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prefill_servers, decode_servers = (
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load_balancer.prefill_servers,
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load_balancer.decode_servers,
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)
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prefill_infos = []
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decode_infos = []
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all_internal_states = []
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async with aiohttp.ClientSession() as session:
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for server in chain(prefill_servers):
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server_info = await session.get(f"{server}/get_server_info")
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prefill_infos.append(await server_info.json())
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for server in chain(decode_servers):
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server_info = await session.get(f"{server}/get_server_info")
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info_json = await server_info.json()
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decode_infos.append(info_json)
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# Extract internal_states from decode servers
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if "internal_states" in info_json:
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all_internal_states.extend(info_json["internal_states"])
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# Return format expected by bench_one_batch_server.py
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if all_internal_states:
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return {
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"internal_states": all_internal_states,
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"prefill": prefill_infos,
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"decode": decode_infos,
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}
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else:
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# Fallback with dummy data if no internal states found
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return {
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"internal_states": [
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{
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"last_gen_throughput": 0.0,
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"avg_spec_accept_length": None,
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}
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],
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"prefill": prefill_infos,
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"decode": decode_infos,
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}
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@app.get("/get_model_info")
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async def get_model_info():
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global load_balancer
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if not load_balancer or not load_balancer.prefill_servers:
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raise HTTPException(
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status_code=HTTPStatus.SERVICE_UNAVAILABLE,
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detail="There is no server registered",
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)
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target_server_url = load_balancer.prefill_servers[0]
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endpoint_url = f"{target_server_url}/get_model_info"
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async with aiohttp.ClientSession() as session:
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try:
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async with session.get(endpoint_url) as response:
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if response.status != 200:
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error_text = await response.text()
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raise HTTPException(
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status_code=HTTPStatus.BAD_GATEWAY,
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detail=(
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f"Failed to get model info from {target_server_url}"
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f"Status: {response.status}, Response: {error_text}"
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),
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)
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model_info_json = await response.json()
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return ORJSONResponse(content=model_info_json)
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except aiohttp.ClientError as e:
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raise HTTPException(
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status_code=HTTPStatus.SERVICE_UNAVAILABLE,
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detail=f"Failed to get model info from backend",
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)
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@app.post("/generate")
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async def handle_generate_request(request_data: dict):
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prefill_server, bootstrap_port, decode_server = load_balancer.select_pair()
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# Parse and transform prefill_server for bootstrap data
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parsed_url = urllib.parse.urlparse(prefill_server)
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hostname = maybe_wrap_ipv6_address(parsed_url.hostname)
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modified_request = request_data.copy()
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batch_size = _get_request_batch_size(modified_request)
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if batch_size is not None:
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modified_request.update(
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{
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"bootstrap_host": [hostname] * batch_size,
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"bootstrap_port": [bootstrap_port] * batch_size,
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"bootstrap_room": [
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_generate_bootstrap_room() for _ in range(batch_size)
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],
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}
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)
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else:
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modified_request.update(
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{
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"bootstrap_host": hostname,
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"bootstrap_port": bootstrap_port,
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"bootstrap_room": _generate_bootstrap_room(),
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}
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)
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if request_data.get("stream", False):
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return await load_balancer.generate_stream(
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modified_request, prefill_server, decode_server, "generate"
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)
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else:
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return await load_balancer.generate(
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modified_request, prefill_server, decode_server, "generate"
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)
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async def _forward_to_backend(request_data: dict, endpoint_name: str):
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prefill_server, bootstrap_port, decode_server = load_balancer.select_pair()
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# Parse and transform prefill_server for bootstrap data
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parsed_url = urllib.parse.urlparse(prefill_server)
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hostname = maybe_wrap_ipv6_address(parsed_url.hostname)
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modified_request = request_data.copy()
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modified_request.update(
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{
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"bootstrap_host": hostname,
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"bootstrap_port": bootstrap_port,
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"bootstrap_room": _generate_bootstrap_room(),
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}
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)
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if request_data.get("stream", False):
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return await load_balancer.generate_stream(
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modified_request,
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prefill_server,
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decode_server,
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endpoint=endpoint_name,
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)
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else:
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return await load_balancer.generate(
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modified_request,
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prefill_server,
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decode_server,
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endpoint=endpoint_name,
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)
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@app.post("/v1/chat/completions")
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async def handle_chat_completion_request(request_data: dict):
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return await _forward_to_backend(request_data, "v1/chat/completions")
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@app.post("/v1/completions")
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async def handle_completion_request(request_data: dict):
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return await _forward_to_backend(request_data, "v1/completions")
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def _generate_bootstrap_room():
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return random.randint(0, 2**63 - 1)
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# We may utilize `GenerateReqInput`'s logic later
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def _get_request_batch_size(request):
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if (text := request.get("text")) is not None:
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return None if isinstance(text, str) else len(text)
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if (input_ids := request.get("input_ids")) is not None:
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return None if isinstance(input_ids[0], int) else len(input_ids)
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return None
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@app.get("/v1/models")
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async def get_models():
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prefill_server = load_balancer.prefill_servers[0] # Get the first prefill server
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async with aiohttp.ClientSession() as session:
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try:
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response = await session.get(f"{prefill_server}/v1/models")
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if response.status != 200:
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raise HTTPException(
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status_code=response.status,
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detail=f"Prefill server error: Status {response.status}",
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)
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return ORJSONResponse(content=await response.json())
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except Exception as e:
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raise HTTPException(status_code=500, detail=str(e))
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@app.post("/register")
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async def register(obj: PDRegistryRequest):
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if obj.mode == "prefill":
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load_balancer.add_prefill_server(
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PrefillConfig(obj.registry_url, obj.bootstrap_port)
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)
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logger.info(
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f"Registered prefill server: {obj.registry_url} with bootstrap port: {obj.bootstrap_port}"
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)
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elif obj.mode == "decode":
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load_balancer.add_decode_server(obj.registry_url)
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logger.info(f"Registered decode server: {obj.registry_url}")
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else:
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raise HTTPException(
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status_code=400,
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detail="Invalid mode. Must be either PREFILL or DECODE.",
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)
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logger.info(
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f"#Prefill servers: {len(load_balancer.prefill_configs)}, "
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f"#Decode servers: {len(load_balancer.decode_servers)}"
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)
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return Response(status_code=200)
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def run(prefill_configs, decode_addrs, host, port, timeout):
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global load_balancer
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load_balancer = MiniLoadBalancer(prefill_configs, decode_addrs, timeout=timeout)
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uvicorn.run(app, host=host, port=port)
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if __name__ == "__main__":
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# FIXME: remove this, use the unified entry point: sglang.srt.disaggregation.launch_lb
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from sglang.srt.disaggregation.launch_lb import main
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main()
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