lib/workers.js

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