README.MD

   1 # Node 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 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>
  22 The first implementation is a static thread pool , with a defined number of threads that are started at creation time .<br>
  23 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>
  24 You have to implement your worker extending the ThreadWorker class<br>
  25 <h2 id="installation">Installation</h2>
  26
  27 ```
  28 npm install node-pool --save
  29 ```
  30 <h2 id="usage">Usage</h2>
  31
  32 You can implement a worker in a simple way , extending the class ThreadWorker :
  33
  34 ```js
  35 'use strict'
  36 const { ThreadWorker } = require('node-pool')
  37
  38 class MyWorker extends ThreadWorker {
  39   constructor () {
  40     super((data) => {
  41       // this will be executed in the worker thread,
  42       // the data will be received by using the execute method
  43       return { ok: 1 }
  44     }, { maxInactiveTime: 1000 * 60})
  45   }
  46 }
  47 module.exports = new MyWorker()
  48 ```
  49
  50 Instantiate your pool based on your needed :
  51
  52 ```js
  53 'use strict'
  54 const { FixedThreadPool, DynamicThreadPool } = require('node-pool')
  55
  56 // a fixed thread pool
  57 const pool = new FixedThreadPool(15,
  58   './yourWorker.js')
  59
  60 // or a dynamic thread pool
  61 const pool = new DynamicThreadPool(10, 100,
  62   './yourWorker.js')
  63 pool.emitter.on('FullPool', () => console.log('Pool is full'))
  64
  65 // the execute method signature is the same for both implementations,
  66 // so you can easy switch from one to another
  67 pool.execute({}).then(res => {
  68   console.log(res)
  69 }).catch ....
  70
  71 ```
  72
  73 <strong> See examples folder for more details.</strong>
  74
  75 <h2 id="nv">Node versions</h2>
  76
  77 You can use node version  10.x  with --experimental-worker flag, or you can use an higher version (i.e 12.x) <br>
  78
  79 <h2 id="api">API</h2>
  80
  81 ### `pool = new FixedThreadPool(numThreads, filePath, opts)`
  82 `numThreads` (mandatory) Num of threads for this worker pool <br>
  83 `filePath` (mandatory) Path to a file with a worker implementation <br>
  84 `opts` (optional) An object with these properties :
  85 - `errorHandler` - A function that will listen for error event on each worker thread
  86 - `onlineHandler` - A function that will listen for online event on each worker thread
  87 - `exitHandler` - A function that will listen for exit event on each worker thread
  88 - `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)
  89
  90 ### `pool = new DynamicThreadPool(min, max, filePath, opts)`
  91 `min` (mandatory) Same as FixedThreadPool numThreads , this number of threads will be always active <br>
  92 `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>
  93 `filePath` (mandatory) Same as FixedThreadPool  <br>
  94 `opts` (optional) Same as FixedThreadPool <br>
  95
  96 ### `pool.execute(data)`
  97 Execute method is available on both pool implementations ( return type : Promise): <br>
  98 `data` (mandatory) An object that you want to pass to your worker implementation <br>
  99
 100 ### `pool.destroy()`
 101 Destroy method is available on both pool implementations.<br>
 102 This method will call the terminate method on each worker.
 103
 104
 105 ### `class YourWorker extends ThreadWorker`
 106 `fn` (mandatory) The function that you want to execute on the worker thread <br>
 107 `opts` (optional) An object with these properties :
 108 - `maxInactiveTime` - Max time to wait tasks to work on ( in ms) , after this period the new worker threads will die.
 109
 110 <h2 id="contribute">Contribute</h2>
 111
 112 See guidelines [CONTRIBUTING](./.github/CONTRIBUTING.md)
 113
 114
 115 <h2 id="license">License</h2>
 116
 117 [MIT](https://github.com/pioardi/node-pool/blob/master/LICENSE)
 118