lib/workers.js

   1 'use strict'
   2 const { isMainThread, parentPort } = require('worker_threads')
   3 const { AsyncResource } = require('async_hooks')
   4
   5 /**
   6  * An example worker that will be always alive, you just need to extend this class if you want a static pool.<br>
   7  * When this worker is inactive for more than 1 minute, it will send this info to the main thread,<br>
   8  * if you are using DynamicThreadPool, the workers created after will be killed, the min num of thread will be guaranteed
   9  * @author Alessandro Pio Ardizio
  10  * @since 0.0.1
  11  */
  12 class ThreadWorker extends AsyncResource {
  13   constructor (fn, opts) {
  14     super('worker-thread-pool:pioardi')
  15     this.opts = opts || {}
  16     this.maxInactiveTime = this.opts.maxInactiveTime || 1000 * 60
  17     this.async = !!this.opts.async
  18     this.lastTask = Date.now()
  19     if (!fn) throw new Error('Fn parameter is mandatory')
  20     // keep the worker active
  21     if (!isMainThread) {
  22       this.interval = setInterval(
  23         this._checkAlive.bind(this),
  24         this.maxInactiveTime / 2
  25       )
  26       this._checkAlive.bind(this)()
  27     }
  28     parentPort.on('message', value => {
  29       if (value && value.data && value._id) {
  30         // here you will receive messages
  31         // console.log('This is the main thread ' + isMainThread)
  32         if (this.async) {
  33           this.runInAsyncScope(this._runAsync.bind(this), this, fn, value)
  34         } else {
  35           this.runInAsyncScope(this._run.bind(this), this, fn, value)
  36         }
  37       } else if (value.parent) {
  38         // save the port to communicate with the main thread
  39         // this will be received once
  40         this.parent = value.parent
  41       } else if (value.kill) {
  42         // here is time to kill this thread, just clearing the interval
  43         clearInterval(this.interval)
  44         this.emitDestroy()
  45       }
  46     })
  47   }
  48
  49   _checkAlive () {
  50     if (Date.now() - this.lastTask > this.maxInactiveTime) {
  51       this.parent.postMessage({ kill: 1 })
  52     }
  53   }
  54
  55   _run (fn, value) {
  56     try {
  57       const res = fn(value.data)
  58       this.parent.postMessage({ data: res, _id: value._id })
  59       this.lastTask = Date.now()
  60     } catch (e) {
  61       this.parent.postMessage({ error: e, _id: value._id })
  62       this.lastTask = Date.now()
  63     }
  64   }
  65
  66   _runAsync (fn, value) {
  67     fn(value.data)
  68       .then(res => {
  69         this.parent.postMessage({ data: res, _id: value._id })
  70         this.lastTask = Date.now()
  71       })
  72       .catch(e => {
  73         this.parent.postMessage({ error: e, _id: value._id })
  74         this.lastTask = Date.now()
  75       })
  76   }
  77 }
  78
  79 module.exports.ThreadWorker = ThreadWorker