Respond to Koa request immediately, continue middleware chain about discussions HOT 5 OPEN

// thread-service.js
'use strict'

const {Worker, isMainThread} = require('worker_threads')

function runService(service, workerData) {
  if (isMainThread === false) {
    return
  }
  const worker = new Worker(service, {workerData})
  worker.once('message', console.log)
  worker.once('exit', code => {
    worker.removeAllListeners()
    worker.terminate()
    if (code !== 0) {
      new Error(`Worker stopped with exit code ${code}`)
    }
  })
}

module.exports = runService

// service.js
'use strict'

const {workerData, parentPort} = require('worker_threads')
// const db = require('./my-db')

;(async () => {
  try {
    // do your stuff with data
    // const result = await db.save(workerData)
    console.log('thread --->', workerData)
    const result = Math.random()
    parentPort.postMessage({result})
    process.exit(0)
  } catch (error) {
    process.exit(1)
  }
})()

// app.js
'use strict'

const {join} = require('path')
const Koa = require('koa')
const runService = require('./thread-service.js')

const app = new Koa()

app
  .use(async (ctx, next) => {
    const start = Date.now()
    ctx.state.start = start
    console.log('start --> goto b')
    await next() // goto b
    // a
    const ms = Date.now() - start
    ctx.set('X-Response-Time', ms)
    console.log('a --> end')
  })
  .use(async (ctx, next) => {
    // b
    const {start} = ctx.state
    // start thread and keep running
    runService(join(__dirname, 'service.js'), {start})
    console.log('b --> goto c')
    await next() // goto c
    // b2
    // goto a
    console.log('b2 --> goto a')
  })
  .use(ctx => {
    // c
    ctx.body = {ok: true}
    // goto b2
    console.log('c --> goto b2')
  })
  .on('error', console.error)

app.proxy = true

app.listen(3435, () => {
  console.log('Running: http://[::1]:3435')
})