Question

关于以下代码，应用程序应在每个连接上分叉4个worker，然后每个worker发送一条消息并断开连接。

但是，在第一次连接后，<lvc:CartesianChart Hoverable="False" DataTooltip="{x:Null}" />会逐渐收到消息。

cluster.on('message')

首先输出：

const express = require('express');
const cluster = require('cluster');

if (cluster.isMaster) {
  const app = express();
  app.get('/', (req, res) => {
    [1, 2, 3, 4].map(() => cluster.fork());

    const count = [];
    cluster.on('message', (worker, message) => {
      console.log({
        worker: worker.id,
        message
      });
      count.push(true);
      if (count.length === 4)
        return res.sendStatus(200);
    });
  });
  app.listen(8000, () => console.log('listening on 8000'));
} else if (cluster.isWorker) {
  process.send('msg');
  process.disconnect();
}

然后

> curl localhost:8000
> { worker: 4, message: 'msg' }
> { worker: 1, message: 'msg' }
> { worker: 2, message: 'msg' }
> { worker: 3, message: 'msg' }

依旧......

我无法理解为什么会这样。

Answer 1

您的问题源于您使用.on（“message”，...）的方式。实际上，每次调用服务器时都会注册监听器。

将侦听器中的“push to count”部分移出API调用可以解决此问题：

if (cluster.isMaster) {
  let count = [];
  cluster.on('message', (worker, message) => {
    console.log({
      worker: worker.id,
      message
    });
    count.push(true);
  });

  const app = express();
  app.get('/', (req, res) => {
    [1, 2, 3, 4].forEach(() => cluster.fork());

    let msgHandler = (worker, message) => {
      if (count.length === 4) {
        cluster.removeListener('message', msgHandler); // Do not forget to remove this event listener, or the issue will arise again!
        count.length = 0;
        return res.sendStatus(200);
      }
    };

    cluster.on('message', msgHandler);
  });
  app.listen(10101, () => console.log('listening on 10101'));
} else if (cluster.isWorker) {
  process.send('msg');
  process.disconnect();
}

多次调用集群事件消息

1 个答案: