javascript - Nodejs 和 Express，从工作线程使用 res.send()

Question

在 Nodejs 中，使用 Express 作为服务器，我将繁重的计算卸载到工作线程上。

在主应用程序中，我这样调用工作线程:

// file: main.js

const { Worker } = require("worker_threads");

function runService(fileName, workerData) {
    return new Promise((resolve, reject) => {
        const worker = new Worker(fileName, { workerData });
        worker.on("message", resolve);
        worker.on("error", reject);
        worker.on("exit", code => {
            if (code !== 0)
                reject(new Error(`Worker stopped with exit code ${code}`));
        });
    });
}

router.get("/some_url", async function(req, res) {
    const result = await runService(
        "./path/to/worker.js",
        { query: req.query, user: req.user } // using { req } causes an error
    );
});

worker 看起来像这样:

// file: worker.js

const { workerData, parentPort } = require('worker_threads');
const { query, user } = workerData;

async function run() {
    const result = await generateLotsOfData(query, user);

    parentPort.postMessage(result);

    // What I would like to do here (doesn't work): res.send(result);
}

worker 生成大量数据，“postMessage”导致服务器错误。

有没有办法使用 res.send() 或类似的东西将这些数据从工作线程直接发送到客户端？
(而不是使用 postMessage 然后从主线程发送)？

Answer 1

此代码示例有效:

1. 创建工作人员
2. 创建事件处理程序
3. sendMessage --> 包装器WorkerThreadBigComputing
4. 在我们的主线程上发送消息
5. 发出服务器响应

API 路线:

app.get('/bigComputingWithWorker', (req, res) => {
     const worker = new Worker(`${__dirname}/src/wrapperWorkerThreadBigComputing.js`);
    res.set('Content-Type', 'text/html');
      worker.once("message", count => {
        res.status(200).send(`The final count :${count}`);
    });
    worker.once("error", err => {
        console.error(err);
        res.status(400).send(`error worker thread`);
    });
     worker.postMessage({coucou : 'john'});
});

wrapperWorkerThreadBigComputing

const { parentPort } = require('node:worker_threads');

console.log("* worker created");
parentPort.once('message', (message) => {
      let big = bigComputing();
      parentPort.postMessage(big);
})

function bigComputing() {
    let i = 0;
    console.log("* start big computing")
    for (i = 0; i < 300000000; i++) {
    }
    return i;
}