lib/workers.js

   1 'use strict'
   2 const {
   3   isMainThread, parentPort
   4 } = require('worker_threads')
   5 const { AsyncResource } = require('async_hooks')
   6
   7 /**
   8  * An example worker that will be always alive, you just need to extend this class if you want a static pool.<br>
   9  * When this worker is inactive for more than 1 minute, it will send this info to the main thread,<br>
  10  * if you are using DynamicThreadPool, the workers created after will be killed, the min num of thread will be guaranteed
  11  * @author Alessandro Pio Ardizio
  12  * @since 0.0.1
  13  */
  14 class ThreadWorker extends AsyncResource {
  15   constructor (fn, opts) {
  16     super('worker-thread-pool:pioardi')
  17     this.opts = opts || {}
  18     this.maxInactiveTime = this.opts.maxInactiveTime || (1000 * 60)
  19     this.lastTask = Date.now()
  20     if (!fn) throw new Error('Fn parameter is mandatory')
  21     // keep the worker active
  22     if (!isMainThread) {
  23       this.interval = setInterval(this._checkAlive.bind(this), this.maxInactiveTime / 2)
  24       this._checkAlive.bind(this)()
  25     }
  26     parentPort.on('message', (value) => {
  27       if (value && value.data && value._id) {
  28         // here you will receive messages
  29         // console.log('This is the main thread ' + isMainThread)
  30         this._run(fn, value)
  31       } else if (value.parent) {
  32         // save the port to communicate with the main thread
  33         // this will be received once
  34         this.parent = value.parent
  35       } else if (value.kill) {
  36         // here is time to kill this thread, just clearing the interval
  37         clearInterval(this.interval)
  38         this.emitDestroy()
  39       }
  40     })
  41   }
  42
  43   _checkAlive () {
  44     if ((Date.now() - this.lastTask) > this.maxInactiveTime) {
  45       this.parent.postMessage({ kill: 1 })
  46     }
  47   }
  48
  49   _run (fn, value) {
  50     try {
  51       const res = this.runInAsyncScope(fn, null, value.data)
  52       this.parent.postMessage({ data: res, _id: value._id })
  53       this.lastTask = Date.now()
  54     } catch (e) {
  55       this.parent.postMessage({ error: e, _id: value._id })
  56       this.lastTask = Date.now()
  57     }
  58   }
  59 }
  60
  61 module.exports.ThreadWorker = ThreadWorker