README.md

   1 # Node Thread Pool :arrow_double_up: :on:
   2
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  12
  13 <div align="center">
  14 <img src="./docs/logo.png" width="250" height="300"/>
  15 </div>
  16
  17 ## Why Poolifier?
  18
  19 Poolifier is used to perform heavy CPU bound tasks on nodejs servers, it implements thread pools (yes, more thread pool implementations, so you can choose which one fit better for you) using [worker-threads](https://nodejs.org/api/worker_threads.html#worker_threads_worker_threads).
  20 With poolifier you can improve your **performance** and resolve problems related to the event loop.
  21 Moreover you can execute your CPU tasks using an API designed to improve the **developer experience**.
  22
  23 - Performance :racehorse:
  24 - Security :bank: :cop: [![Security Rating](https://sonarcloud.io/api/project_badges/measure?project=pioardi_poolifier&metric=security_rating)](https://sonarcloud.io/dashboard?id=pioardi_poolifier) [![Vulnerabilities](https://sonarcloud.io/api/project_badges/measure?project=pioardi_poolifier&metric=vulnerabilities)](https://sonarcloud.io/dashboard?id=pioardi_poolifier)
  25
  26 - No runtime dependencies :heavy_check_mark:
  27 - Easy to use :couple:
  28 - Easy switch from a pool to another, easy to tune
  29 - Dynamic pool size
  30 - Proper async integration with node async hooks
  31 - Support for worker threads and cluster node modules
  32 - Active community
  33 - Support sync and async tasks
  34 - General guidance on pools to use
  35 - Widely tested
  36 - Error handling out of the box
  37 - Code quality :octocat: [![Bugs](https://sonarcloud.io/api/project_badges/measure?project=pioardi_poolifier&metric=bugs)](https://sonarcloud.io/dashboard?id=pioardi_poolifier)
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  43
  44
  45 ## Contents
  46
  47 <h3 align="center">
  48   <a href="#overview">Overview</a>
  49   <span> · </span>
  50   <a href="#installation">Installation</a>
  51   <span> · </span>
  52   <a href="#usage">Usage</a>
  53   <span> · </span>
  54   <a href="#node-versions">  Node versions</a>
  55   <span> · </span>
  56   <a href="#api">API</a>
  57   <span> · </span>
  58   <a href="#choose-your-pool">Choose your pool</a>
  59   <span> · </span>
  60   <a href="#contribute">Contribute</a>
  61   <span> · </span>
  62   <a href="#team">Team</a>
  63   <span> · </span>
  64   <a href="#license">License</a>
  65 </h3>
  66
  67 ## Overview
  68
  69 Node pool contains two [worker-threads](https://nodejs.org/api/worker_threads.html#worker_threads_worker_threads) pool implementations, you don't have to deal with worker-threads complexity.
  70 The first implementation is a static thread pool, with a defined number of threads that are started at creation time and will be reused.
  71 The second implementation is a dynamic thread pool with a number of threads started at creation time (these threads will be always active and reused) and other threads created when the load will increase (with an upper limit, these threads will be reused when active), the new created threads will be stopped after a configurable period of inactivity.
  72 You have to implement your worker extending the ThreadWorker class
  73
  74 ## Installation
  75
  76 ```shell
  77 npm install poolifier --save
  78 ```
  79
  80 ## Usage
  81
  82 You can implement a worker in a simple way, extending the class ThreadWorker:
  83
  84 ```js
  85 'use strict'
  86 const { ThreadWorker } = require('poolifier')
  87
  88 function yourFunction (data) {
  89   // this will be executed in the worker thread,
  90   // the data will be received by using the execute method
  91   return { ok: 1 }
  92 }
  93
  94 module.exports = new ThreadWorker(yourFunction, {
  95   maxInactiveTime: 60000,
  96   async: false
  97 })
  98 ```
  99
 100 Instantiate your pool based on your needed :
 101
 102 ```js
 103 'use strict'
 104 const { FixedThreadPool, DynamicThreadPool } = require('poolifier')
 105
 106 // a fixed thread pool
 107 const pool = new FixedThreadPool(15,
 108   './yourWorker.js',
 109   { errorHandler: (e) => console.error(e), onlineHandler: () => console.log('worker is online') })
 110
 111 // or a dynamic thread pool
 112 const pool = new DynamicThreadPool(10, 100,
 113   './yourWorker.js',
 114   { errorHandler: (e) => console.error(e), onlineHandler: () => console.log('worker is online') })
 115
 116 pool.emitter.on('FullPool', () => console.log('Pool is full'))
 117
 118 // the execute method signature is the same for both implementations,
 119 // so you can easy switch from one to another
 120 pool.execute({}).then(res => {
 121   console.log(res)
 122 }).catch ....
 123
 124 ```
 125
 126 **See examples folder for more details (in particular if you want to use a pool for [multiple functions](./examples/multiFunctionExample.js)).**
 127 **Now type script is also supported, find how to use it into the example folder**
 128
 129 ## Node versions
 130
 131 You can use node versions 12.x, 13.x, 14.x
 132
 133 ## API
 134
 135 ### `pool = new FixedThreadPool(numThreads, filePath, opts)`
 136
 137 `numThreads` (mandatory) Num of threads for this worker pool
 138 `filePath` (mandatory) Path to a file with a worker implementation
 139 `opts` (optional) An object with these properties :
 140
 141 - `errorHandler` - A function that will listen for error event on each worker thread
 142 - `onlineHandler` - A function that will listen for online event on each worker thread
 143 - `exitHandler` - A function that will listen for exit event on each worker thread
 144 - `maxTasks` - This is just to avoid not useful warnings message, is used to set [maxListeners](https://nodejs.org/dist/latest-v12.x/docs/api/events.html#events_emitter_setmaxlisteners_n) on event emitters (workers are event emitters)
 145
 146 ### `pool = new DynamicThreadPool(min, max, filePath, opts)`
 147
 148 `min` (mandatory) Same as FixedThreadPool numThreads, this number of threads will be always active
 149 `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).
 150 `filePath` (mandatory) Same as FixedThreadPool
 151 `opts` (optional) Same as FixedThreadPool
 152
 153 ### `pool.execute(data)`
 154
 155 Execute method is available on both pool implementations (return type : Promise):
 156 `data` (mandatory) An object that you want to pass to your worker implementation
 157
 158 ### `pool.destroy()`
 159
 160 Destroy method is available on both pool implementations.
 161 This method will call the terminate method on each worker.
 162
 163 ### `class YourWorker extends ThreadWorker`
 164
 165 `fn` (mandatory) The function that you want to execute on the worker thread
 166 `opts` (optional) An object with these properties:
 167
 168 - `maxInactiveTime` - Max time to wait tasks to work on ( in ms) , after this period the new worker threads will die.
 169 - `async` - true/false, true if your function contains async pieces else false
 170
 171 ## Choose your pool
 172
 173 Performance is one of the main target of these thread pool implementations, we want to have a strong focus on this.
 174 We already have a bench folder where you can find some comparisons.
 175 To choose your pool consider that with a FixedThreadPool or a DynamicThreadPool (in this case is important the min parameter passed to the constructor) your application memory footprint will increase.
 176 Increasing the memory footprint, your application will be ready to accept more CPU bound tasks, but during idle time your application will consume more memory.
 177 One good choose from my point of view is to profile your application using Fixed/Dynamic thread pool, and to see your application metrics when you increase/decrease the num of threads.
 178 For example you could keep the memory footprint low choosing a DynamicThreadPool with 5 threads, and allow to create new threads until 50/100 when needed, this is the advantage to use the DynamicThreadPool.
 179 But in general, **always profile your application**
 180
 181 ## Contribute
 182
 183 See guidelines [CONTRIBUTING](CONTRIBUTING.md)
 184 Choose your task here [2.0.0](https://github.com/pioardi/poolifier/projects/1), propose an idea, a fix, an improvement.
 185
 186 ## Team
 187
 188 <!-- ALL-CONTRIBUTORS-LIST:START - Do not remove or modify this section -->
 189 <!-- prettier-ignore-start -->
 190 <!-- markdownlint-disable -->
 191
 192 **Creator/Owner:**
 193
 194 - [**Alessandro Pio Ardizio**](https://github.com/pioardi)
 195
 196 **_Contributors_**
 197
 198 - [**Shinigami92**](https://github.com/Shinigami92)
 199 - [**Jérôme Benoit**](https://github.com/jerome-benoit)
 200
 201 ## License
 202
 203 [MIT](./LICENSE)