Node.js接口返回响应时卡在emitHook函数的问题求助

我用Visual Studio 2022社区版开发小型Node.js应用，遇到两个核心问题：

• 用户注册路由返回response时，卡在emitHook后端函数，哪怕移除return语句、注释res对象依然如此，调试时添加"skipFiles": [ "<node_internals>/**" ]也未解决。
• 新建发票路由同样异常：客户端发送fetch请求后收不到响应，Chrome开发者工具显示请求已发送但无法加载响应数据，添加CORS配置也无效。怀疑是Promise相关逻辑导致，求技术帮助。

注册路由代码 #

registrationRoute.post('/register', async function (req, res) { 
    try {
        await mongoose.connect(uri);
        const { username, password, company } = req.body;
        const existingUser = await User.findOne({ userName : username  });
        if (existingUser) {
            return res.send({ error: "User Name already Taken" });
        }
        const newUser = new User({
            userName : username,
            password: password,
            company: company
        })
        await newUser.save();
        console.log("user successfully registered")
        token = generateToken(newUser.userName)
        return res.status(200).json({token})
    } catch (err) {
        console.error(err)
        return res.status(500).json("unable to register user")
    }
})

emitHook函数代码 #

function emitHook(symbol, asyncId) {
  active_hooks.call_depth += 1;
  // Use a single try/catch for all hook to avoid setting up one per
  // iteration.
  try {
    // Using var here instead of let because "for (var ...)" is faster than let.
    // Refs: https://github.com/nodejs/node/pull/30380#issuecomment-552948364
    // eslint-disable-next-line no-var
    for (var i = 0; i < active_hooks.array.length; i++) {
      if (typeof active_hooks.array[i][symbol] === 'function') {
        active_hooks.array[i][symbol](asyncId);
      }
    }
  } catch (e) {
    fatalError(e);
  } finally {
    active_hooks.call_depth -= 1;
  }

  // Hooks can only be restored if there have been no recursive hook calls.
  // Also the active hooks do not need to be restored if enable()/disable()
  // weren't called during hook execution, in which case
  // active_hooks.tmp_array will be null.
  if (active_hooks.call_depth === 0 && active_hooks.tmp_array !== null) {
    restoreActiveHooks();
  }
}

新建发票客户端代码 #

try{
var res = await fetch('/newInvoice',
    {
        method: 'POST',
        headers: {
            'content-type': 'application/json',
        },
        body: JSON.stringify({ message: "sending to server" })
    })
if (res.ok) {
    document.getElementById("invoiceCreatedMessage").innerHTML = "Invoice Successfully created"
}
}catch(err) {
console.log("there was an error: ", err);
}

新建发票路由代码 #

newInvoiceRoute.post('/newInvoice', function (req, res) {
    res.send({"message": "sending to client"});
})

问题排查与修复建议 #

1. 修复数据库重复连接问题
   注册路由中每次请求都调用await mongoose.connect(uri)会重复创建数据库连接，导致连接池阻塞，进而卡住响应流程。应在应用启动时仅连接一次数据库：

   // 入口文件（如app.js）
   const mongoose = require('mongoose');
   const uri = '你的数据库地址';
   
   async function startServer() {
     try {
       await mongoose.connect(uri);
       console.log('数据库连接成功');
       app.listen(3000, () => console.log('服务器启动'));
     } catch (err) {
       console.error('数据库连接失败', err);
     }
   }
   startServer();
   

   随后删除注册路由中的await mongoose.connect(uri);语句。

2. 排查异步钩子阻塞
   emitHook是Node.js内部异步钩子函数，卡住说明项目中存在使用async_hooks的第三方库或自定义代码，存在阻塞或死循环。暂时禁用这类代码，测试是否恢复正常。

3. 优化调试配置
   确保VSCode的.vscode/launch.json配置正确，重启调试会话生效：

   {
     "version": "0.2.0",
     "configurations": [
       {
         "type": "node",
         "request": "launch",
         "name": "Launch Program",
         "skipFiles": [
           "<node_internals>/**"
         ],
         "program": "${workspaceFolder}/app.js"
       }
     ]
   }
   

4. 完善客户端请求逻辑
   客户端fetch若未读取响应体，会导致服务端认为请求未完成，进而卡住连接。补充响应体读取逻辑：

   try {
     const res = await fetch('/newInvoice', {
       method: 'POST',
       headers: { 'content-type': 'application/json' },
       body: JSON.stringify({ message: "sending to server" })
     });
     if (res.ok) {
       const data = await res.json(); // 必须读取响应体
       document.getElementById("invoiceCreatedMessage").innerHTML = "Invoice Successfully created";
     }
   } catch(err) {
     console.log("there was an error: ", err);
   }
   

   同时确保服务端全局启用CORS：

   const cors = require('cors');
   app.use(cors());
   

内容的提问来源于stack exchange，提问作者Jonny O