---
description: "FastAPI 部署的约定：性能依赖、生产启动、API 文档控制、线程池调整、中间件性能"
---

# FastAPI 部署

## 性能依赖

安装 `uvloop` 和 `httptools` 以获得更好的性能（Uvicorn 检测到会自动启用）：

```bash
pip install uvloop httptools
```

> uvloop 不支持 Windows。可用环境标记处理：`uvloop; sys_platform != 'win32'`

## 生产启动

```bash
uvicorn src.main:app --host 0.0.0.0 --port 8000 --workers 4
```

或使用 gunicorn + uvicorn worker：

```bash
gunicorn src.main:app -w 4 -k uvicorn.workers.UvicornWorker --bind 0.0.0.0:8000
```

## API 文档控制

非公开 API 在生产环境隐藏文档：

```python
from pydantic_settings import BaseSettings

class Config(BaseSettings):
    ENVIRONMENT: str = "production"

settings = Config()

SHOW_DOCS_ENVIRONMENTS = ("local", "staging")

app_configs = {"title": "My API"}
if settings.ENVIRONMENT not in SHOW_DOCS_ENVIRONMENTS:
    app_configs["openapi_url"] = None

app = FastAPI(**app_configs)
```

## 线程池调整

默认线程池只有 40 个线程。高并发场景可在 lifespan 里调大：

```python
import anyio
from contextlib import asynccontextmanager

@asynccontextmanager
async def lifespan(app: FastAPI):
    limiter = anyio.to_thread.current_default_thread_limiter()
    limiter.total_tokens = 100
    yield

app = FastAPI(lifespan=lifespan)
```

## 中间件性能

避免使用 `BaseHTTPMiddleware`（`@app.middleware("http")` 也是它的包装），有性能损耗。
需要中间件时优先实现纯 ASGI 中间件：

```python
class MyMiddleware:
    def __init__(self, app):
        self.app = app

    async def __call__(self, scope, receive, send):
        if scope["type"] == "http":
            # 前置处理
            pass
        await self.app(scope, receive, send)
```