README.MD

   1 # Node Thread Pool :arrow_double_up: :on:
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   5
   6 <h2>Contents </h2>
   7 <h3 align="center">
   8   <a href="#installation">Installation</a>
   9   <span> · </span>
  10   <a href="#usage">Usage</a>
  11   <span> · </span>
  12   <a href="#api">API</a>
  13   <span> · </span>
  14   <a href="#contribute">Contribute</a>
  15   <span> · </span>
  16   <a href="#nv">Compatibility</a>
  17   <span> · </span>
  18   <a href="#license">License</a>
  19 </h3>
  20
  21 <h2> Overview </h2>
  22 Node pool contains two <a href="https://nodejs.org/api/worker_threads.html#worker_threads_worker_threads">worker-threads </a> pool implementations , you don' t have to deal with worker-threads complexity. <br>
  23 The first implementation is a static thread pool , with a defined number of threads that are started at creation time .<br>
  24 The second implementation is a dynamic thread pool with a number of threads started at creation time and other threads created when the load will increase ( with an upper limit ), the new created threads will be stopped after a threshold. <br>
  25 You have to implement your worker extending the ThreadWorker class<br>
  26 <h2 id="installation">Installation</h2>
  27
  28 ```
  29 npm install node-thread-pool --save
  30 ```
  31 <h2 id="usage">Usage</h2>
  32
  33 You can implement a worker in a simple way , extending the class ThreadWorker :
  34
  35 ```js
  36 'use strict'
  37 const { ThreadWorker } = require('node-pool')
  38
  39 class MyWorker extends ThreadWorker {
  40   constructor () {
  41     super((data) => {
  42       // this will be executed in the worker thread,
  43       // the data will be received by using the execute method
  44       return { ok: 1 }
  45     }, { maxInactiveTime: 1000 * 60})
  46   }
  47 }
  48 module.exports = new MyWorker()
  49 ```
  50
  51 Instantiate your pool based on your needed :
  52
  53 ```js
  54 'use strict'
  55 const { FixedThreadPool, DynamicThreadPool } = require('node-pool')
  56
  57 // a fixed thread pool
  58 const pool = new FixedThreadPool(15,
  59   './yourWorker.js')
  60
  61 // or a dynamic thread pool
  62 const pool = new DynamicThreadPool(10, 100,
  63   './yourWorker.js')
  64 pool.emitter.on('FullPool', () => console.log('Pool is full'))
  65
  66 // the execute method signature is the same for both implementations,
  67 // so you can easy switch from one to another
  68 pool.execute({}).then(res => {
  69   console.log(res)
  70 }).catch ....
  71
  72 ```
  73
  74 <strong> See examples folder for more details.</strong>
  75
  76 <h2 id="nv">Node versions</h2>
  77
  78 You can use node version  10.x  with --experimental-worker flag, or you can use an higher version (i.e 12.x) <br>
  79
  80 <h2 id="api">API</h2>
  81
  82 ### `pool = new FixedThreadPool(numThreads, filePath, opts)`
  83 `numThreads` (mandatory) Num of threads for this worker pool <br>
  84 `filePath` (mandatory) Path to a file with a worker implementation <br>
  85 `opts` (optional) An object with these properties :
  86 - `errorHandler` - A function that will listen for error event on each worker thread
  87 - `onlineHandler` - A function that will listen for online event on each worker thread
  88 - `exitHandler` - A function that will listen for exit event on each worker thread
  89 - `maxTasks` - This is just to avoid not useful warnings message, is used to set <a href="https://nodejs.org/dist/latest-v12.x/docs/api/events.html#events_emitter_setmaxlisteners_n">maxListeners</a> on event emitters ( workers are event emitters)
  90
  91 ### `pool = new DynamicThreadPool(min, max, filePath, opts)`
  92 `min` (mandatory) Same as FixedThreadPool numThreads , this number of threads will be always active <br>
  93 `max` (mandatory) Max number of workers that this pool can contain, the new created threads will die after a threshold ( default is 1 minute , you can override it in your worker implementation). <br>
  94 `filePath` (mandatory) Same as FixedThreadPool  <br>
  95 `opts` (optional) Same as FixedThreadPool <br>
  96
  97 ### `pool.execute(data)`
  98 Execute method is available on both pool implementations ( return type : Promise): <br>
  99 `data` (mandatory) An object that you want to pass to your worker implementation <br>
 100
 101 ### `pool.destroy()`
 102 Destroy method is available on both pool implementations.<br>
 103 This method will call the terminate method on each worker.
 104
 105
 106 ### `class YourWorker extends ThreadWorker`
 107 `fn` (mandatory) The function that you want to execute on the worker thread <br>
 108 `opts` (optional) An object with these properties :
 109 - `maxInactiveTime` - Max time to wait tasks to work on ( in ms) , after this period the new worker threads will die.
 110
 111 <h2 id="contribute">Contribute</h2>
 112
 113 See guidelines [CONTRIBUTING](./.github/CONTRIBUTING.md)
 114
 115
 116 <h2 id="license">License</h2>
 117
 118 [MIT](./LICENSE)
 119