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: (until now we don't have any expectations to add some)- Easy to use :couple:
  27 - 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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  33 - Easy switch from a pool to another, easy to tune
  34 - Dynamic pool size
  35 - Proper async integration with node async hooks
  36 - Support for worker threads and cluster node modules
  37 - Active community
  38 - Support sync and async tasks
  39 - General guidance on pools to use
  40 - Widely tested
  41 - Error handling out of the box
  42
  43 ## Contents
  44
  45 <h3 align="center">
  46   <a href="#overview">Overview</a>
  47   <span> · </span>
  48   <a href="#installation">Installation</a>
  49   <span> · </span>
  50   <a href="#usage">Usage</a>
  51   <span> · </span>
  52   <a href="#node-versions">  Node versions</a>
  53   <span> · </span>
  54   <a href="#api">API</a>
  55   <span> · </span>
  56   <a href="#choose-your-pool">Choose your pool</a>
  57   <span> · </span>
  58   <a href="#contribute">Contribute</a>
  59   <span> · </span>
  60   <a href="#team">Team</a>
  61   <span> · </span>
  62   <a href="#license">License</a>
  63 </h3>
  64
  65 ## Overview
  66
  67 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.
  68 The first implementation is a static thread pool, with a defined number of threads that are started at creation time and will be reused.
  69 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.
  70 You have to implement your worker extending the ThreadWorker class
  71
  72 ## Installation
  73
  74 ```shell
  75 npm install poolifier --save
  76 ```
  77
  78 ## Usage
  79
  80 You can implement a worker in a simple way, extending the class ThreadWorker:
  81
  82 ```js
  83 'use strict'
  84 const { ThreadWorker } = require('poolifier')
  85
  86 function yourFunction (data) {
  87   // this will be executed in the worker thread,
  88   // the data will be received by using the execute method
  89   return { ok: 1 }
  90 }
  91
  92 module.exports = new ThreadWorker(yourFunction, {
  93   maxInactiveTime: 60000,
  94   async: false
  95 })
  96 ```
  97
  98 Instantiate your pool based on your needed :
  99
 100 ```js
 101 'use strict'
 102 const { FixedThreadPool, DynamicThreadPool } = require('poolifier')
 103
 104 // a fixed thread pool
 105 const pool = new FixedThreadPool(15,
 106   './yourWorker.js',
 107   { errorHandler: (e) => console.error(e), onlineHandler: () => console.log('worker is online') })
 108
 109 // or a dynamic thread pool
 110 const pool = new DynamicThreadPool(10, 100,
 111   './yourWorker.js',
 112   { errorHandler: (e) => console.error(e), onlineHandler: () => console.log('worker is online') })
 113
 114 pool.emitter.on('FullPool', () => console.log('Pool is full'))
 115
 116 // the execute method signature is the same for both implementations,
 117 // so you can easy switch from one to another
 118 pool.execute({}).then(res => {
 119   console.log(res)
 120 }).catch ....
 121
 122 ```
 123
 124 **See examples folder for more details (in particular if you want to use a pool for [multiple functions](./examples/multiFunctionExample.js)).**
 125 **Now type script is also supported, find how to use it into the example folder**
 126
 127 ## Node versions
 128
 129 You can use node versions 12.x, 13.x, 14.x
 130
 131 ## API
 132
 133 ### `pool = new FixedThreadPool(numThreads, filePath, opts)`
 134
 135 `numThreads` (mandatory) Num of threads for this worker pool
 136 `filePath` (mandatory) Path to a file with a worker implementation
 137 `opts` (optional) An object with these properties :
 138
 139 - `errorHandler` - A function that will listen for error event on each worker thread
 140 - `onlineHandler` - A function that will listen for online event on each worker thread
 141 - `exitHandler` - A function that will listen for exit event on each worker thread
 142 - `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)
 143
 144 ### `pool = new DynamicThreadPool(min, max, filePath, opts)`
 145
 146 `min` (mandatory) Same as FixedThreadPool numThreads, this number of threads will be always active
 147 `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).
 148 `filePath` (mandatory) Same as FixedThreadPool
 149 `opts` (optional) Same as FixedThreadPool
 150
 151 ### `pool.execute(data)`
 152
 153 Execute method is available on both pool implementations (return type : Promise):
 154 `data` (mandatory) An object that you want to pass to your worker implementation
 155
 156 ### `pool.destroy()`
 157
 158 Destroy method is available on both pool implementations.
 159 This method will call the terminate method on each worker.
 160
 161 ### `class YourWorker extends ThreadWorker`
 162
 163 `fn` (mandatory) The function that you want to execute on the worker thread
 164 `opts` (optional) An object with these properties:
 165
 166 - `maxInactiveTime` - Max time to wait tasks to work on ( in ms) , after this period the new worker threads will die.
 167 - `async` - true/false, true if your function contains async pieces else false
 168
 169 ## Choose your pool
 170
 171 Performance is one of the main target of these thread pool implementations, we want to have a strong focus on this.
 172 We already have a bench folder where you can find some comparisons.
 173 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.
 174 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.
 175 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.
 176 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.
 177 But in general, **always profile your application**
 178
 179 ## Contribute
 180
 181 See guidelines [CONTRIBUTING](CONTRIBUTING.md)
 182 Choose your task here [2.0.0](https://github.com/pioardi/poolifier/projects/1), propose an idea, a fix, an improvement.
 183
 184 ## Team
 185
 186 <!-- ALL-CONTRIBUTORS-LIST:START - Do not remove or modify this section -->
 187 <!-- prettier-ignore-start -->
 188 <!-- markdownlint-disable -->
 189
 190 **Creator/Owner:**
 191
 192 - [**Alessandro Pio Ardizio**](https://github.com/pioardi)
 193
 194 **_Contributors_**
 195
 196 - [**Shinigami92**](https://github.com/Shinigami92)
 197 - [**Jérôme Benoit**](https://github.com/jerome-benoit)
 198
 199 ## License
 200
 201 [MIT](./LICENSE)