MCP Academy · 课时

生命周期启动钩子

服务器启动时建立一次连接。

生命周期启动钩子 是 CoddyKit 上的免费 MCP Academy 课时。这是第 1 节课，共 4 节。你可以在下方免费阅读本课时的完整内容 — 然后在浏览器中使用内置代码编辑器和全天候 AI 导师进行实践。这是 MCP Academy 学习路径的一部分，你的进度在网页和 CoddyKit 应用中同步。 MCP Academy 课程共包含 4 节课。

本课时的部分内容尚未翻译，以英文显示。

Boot Once, Use Many Times

Some setup should happen once when your server boots, like opening a database connection, not on every single tool call. 🚀

Meet the Lifespan

The lifespan is a hook that runs startup code before requests arrive, then runs teardown code after the server stops.

An Async Context Manager

A lifespan is an async context manager: code before yield is startup, and code after yield is shutdown.

from contextlib import asynccontextmanager

@asynccontextmanager
async def lifespan(server):
    # startup
    yield
    # shutdown

Wire It into FastMCP

You hand your lifespan to the server with the lifespan argument, so FastMCP knows to run it around its life.

from mcp.server.fastmcp import FastMCP

mcp = FastMCP("demo", lifespan=lifespan)

Open Expensive Things Here

The startup block is the right home for expensive setup: database pools, HTTP clients, or loading a model into memory.

Yield the Shared State

Whatever you yield becomes the shared context for every request, so build it once and pass it along.

async def lifespan(server):
    db = await connect_db()
    yield {"db": db}

Startup Runs Before Any Tool

FastMCP guarantees your startup finishes before it accepts the first tool call, so resources are ready in time.

A Typed Context, Optionally

You can yield a small dataclass instead of a dict to get typed, autocompletable access to your shared objects.

from dataclasses import dataclass

@dataclass
class AppCtx:
    db: object

Keep Startup Fast

Clients wait for startup, so keep it lean: connect what you need and defer slow optional work until it is first used.

One Lifespan Per Server

A server has exactly one lifespan. Group all your startup logic inside it rather than scattering setup across tools.

Handle Startup Failures

If startup raises an error, the server should refuse to start rather than run half-configured and fail mysteriously later.

Quick Check

Where in a lifespan does startup code go relative to yield?

Recap: The Lifespan Hook

You learned the lifespan: an async context manager that runs setup before yield, yields shared state, and tears down after. Next, share it. 🎯

常见问题解答

「生命周期启动钩子」课时是免费的吗？

是的 — 「生命周期启动钩子」的完整文本可在网页上免费阅读。要进行交互式练习（内置代码编辑器和全天候 AI 导师）并解锁 MCP Academy 课程的其余内容，请升级到 CoddyKit PRO。 MCP Academy 课程共包含 4 节课。

「生命周期启动钩子」这节课中我会学到什么？

服务器启动时建立一次连接。你通过在浏览器中直接运行的动手代码来练习 MCP Academy，全天候 AI 导师会在你学习这节课的过程中回答你的问题。

学习 MCP Academy 需要有经验吗？

无需任何先前经验。CoddyKit 上的 MCP Academy 课程适合初学者到高级学习者，你可以从这里开始或从头开始，按照自己的节奏学习。这是第 1 节课，共 4 节。

「生命周期启动钩子」课时需要多长时间？

大多数 CoddyKit 课程大约需要 5–10 分钟。每节课都很精短且互动，所以你能稳步进步，并在网页和应用中从离开的地方继续。

我能在这节 MCP Academy 课中编写并运行代码吗？

能。每节 MCP Academy 课都包含内置代码编辑器，你可以在浏览器中直接编写并运行真实代码，并获得即时 AI 反馈 — 无需本地设置。

此课程中的所有课时

← 返回 MCP Academy