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.async = !!this.opts.async
  20     this.lastTask = Date.now()
  21     if (!fn) throw new Error('Fn parameter is mandatory')
  22     // keep the worker active
  23     if (!isMainThread) {
  24       this.interval = setInterval(this._checkAlive.bind(this), this.maxInactiveTime / 2)
  25       this._checkAlive.bind(this)()
  26     }
  27     parentPort.on('message', (value) => {
  28       if (value && value.data && value._id) {
  29         // here you will receive messages
  30         // console.log('This is the main thread ' + isMainThread)
  31         if (this.async) {
  32           this.runInAsyncScope(this._runAsync.bind(this), this, fn, value)
  33         } else {
  34           this.runInAsyncScope(this._run.bind(this), this, fn, value)
  35         }
  36       } else if (value.parent) {
  37         // save the port to communicate with the main thread
  38         // this will be received once
  39         this.parent = value.parent
  40       } else if (value.kill) {
  41         // here is time to kill this thread, just clearing the interval
  42         clearInterval(this.interval)
  43         this.emitDestroy()
  44       }
  45     })
  46   }
  47
  48   _checkAlive () {
  49     if ((Date.now() - this.lastTask) > this.maxInactiveTime) {
  50       this.parent.postMessage({ kill: 1 })
  51     }
  52   }
  53
  54   _run (fn, value) {
  55     try {
  56       const res = fn(value.data)
  57       this.parent.postMessage({ data: res, _id: value._id })
  58       this.lastTask = Date.now()
  59     } catch (e) {
  60       this.parent.postMessage({ error: e, _id: value._id })
  61       this.lastTask = Date.now()
  62     }
  63   }
  64
  65   _runAsync (fn, value) {
  66     fn(value.data).then(res => {
  67       this.parent.postMessage({ data: res, _id: value._id })
  68       this.lastTask = Date.now()
  69     }).catch(e => {
  70       this.parent.postMessage({ error: e, _id: value._id })
  71       this.lastTask = Date.now()
  72     })
  73   }
  74 }
  75
  76 module.exports.ThreadWorker = ThreadWorker