README.md

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   5 <h1 align="center">Node.js Worker_Threads and Cluster Worker Pool</h1>
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  29
  30 ## Why Poolifier?
  31
  32 Poolifier is used to perform CPU and/or I/O intensive tasks on Node.js servers, it implements worker pools using [worker_threads](https://nodejs.org/api/worker_threads.html) and [cluster](https://nodejs.org/api/cluster.html) Node.js modules.
  33 With poolifier you can improve your **performance** and resolve problems related to the event loop.
  34 Moreover you can execute your tasks using an API designed to improve the **developer experience**.
  35 Please consult our [general guidelines](#general-guidelines).
  36
  37 - Easy to use :white_check_mark:
  38 - Performance [benchmarks](./benchmarks/README.md) :white_check_mark:
  39 - Fixed and dynamic pool size :white_check_mark:
  40 - Easy switch from a pool type to another :white_check_mark:
  41 - No runtime dependencies :white_check_mark:
  42 - Proper integration with Node.js [async_hooks](https://nodejs.org/api/async_hooks.html) :white_check_mark:
  43 - Support for CommonJS, ESM, and TypeScript :white_check_mark:
  44 - Support for [worker_threads](https://nodejs.org/api/worker_threads.html) and [cluster](https://nodejs.org/api/cluster.html) Node.js modules :white_check_mark:
  45 - Support for multiple task functions :white_check_mark:
  46 - Support for sync and async task functions :white_check_mark:
  47 - Tasks distribution strategies :white_check_mark:
  48 - Lockless tasks queueing :white_check_mark:
  49 - Queued tasks rescheduling:
  50   - Tasks redistribution on worker error :white_check_mark:
  51   - Tasks stealing under back pressure :white_check_mark:
  52 - General guidelines on pool choice :white_check_mark:
  53 - Error handling out of the box :white_check_mark:
  54 - Widely tested :white_check_mark:
  55 - Active community :white_check_mark:
  56 - Code quality [![Bugs](https://sonarcloud.io/api/project_badges/measure?project=pioardi_poolifier&metric=bugs)](https://sonarcloud.io/dashboard?id=pioardi_poolifier)
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  63
  64 ## Table of contents
  65
  66 - [Overview](#overview)
  67 - [Installation](#installation)
  68 - [Usage](#usage)
  69 - [Node.js versions](#nodejs-versions)
  70 - [API](#api)
  71 - [General guidelines](#general-guidelines)
  72 - [Worker choice strategies](#worker-choice-strategies)
  73 - [Contribute](#contribute)
  74 - [Team](#team)
  75 - [License](#license)
  76
  77 ## Overview
  78
  79 Poolifier contains two [worker_threads](https://nodejs.org/api/worker_threads.html#class-worker)/[cluster](https://nodejs.org/api/cluster.html#cluster_class_worker) worker pool implementations, you don't have to deal with [worker_threads](https://nodejs.org/api/worker_threads.html)/[cluster](https://nodejs.org/api/cluster.html) complexity.
  80 The first implementation is a fixed worker pool, with a defined number of workers that are started at creation time and will be reused.
  81 The second implementation is a dynamic worker pool, with a number of worker started at creation time (these workers will be always active and reused) and other workers created when the load will increase (with an upper limit, these workers will be reused when active), the new created workers will be stopped after a configurable period of inactivity.
  82 You have to implement your worker by extending the _ThreadWorker_ or _ClusterWorker_ class.
  83
  84 ## Installation
  85
  86 ```shell
  87 npm install poolifier --save
  88 ```
  89
  90 ## Usage
  91
  92 You can implement a [worker_threads](https://nodejs.org/api/worker_threads.html#class-worker) worker in a simple way by extending the class _ThreadWorker_:
  93
  94 ```js
  95 'use strict'
  96 const { ThreadWorker } = require('poolifier')
  97
  98 function yourFunction(data) {
  99   // this will be executed in the worker thread,
 100   // the data will be received by using the execute method
 101   return { ok: 1 }
 102 }
 103
 104 module.exports = new ThreadWorker(yourFunction, {
 105   maxInactiveTime: 60000
 106 })
 107 ```
 108
 109 Instantiate your pool based on your needs :
 110
 111 ```js
 112 'use strict'
 113 const { DynamicThreadPool, FixedThreadPool, PoolEvents, availableParallelism } = require('poolifier')
 114
 115 // a fixed worker_threads pool
 116 const pool = new FixedThreadPool(availableParallelism(), './yourWorker.js', {
 117   errorHandler: (e) => console.error(e),
 118   onlineHandler: () => console.info('worker is online')
 119 })
 120
 121 pool.emitter.on(PoolEvents.ready, () => console.info('Pool is ready'))
 122 pool.emitter.on(PoolEvents.busy, () => console.info('Pool is busy'))
 123
 124 // or a dynamic worker_threads pool
 125 const pool = new DynamicThreadPool(Math.floor(availableParallelism() / 2), availableParallelism(), './yourWorker.js', {
 126   errorHandler: (e) => console.error(e),
 127   onlineHandler: () => console.info('worker is online')
 128 })
 129
 130 pool.emitter.on(PoolEvents.full, () => console.info('Pool is full'))
 131 pool.emitter.on(PoolEvents.ready, () => console.info('Pool is ready'))
 132 pool.emitter.on(PoolEvents.busy, () => console.info('Pool is busy'))
 133
 134 // the execute method signature is the same for both implementations,
 135 // so you can easily switch from one to another
 136 pool
 137   .execute()
 138   .then((res) => {
 139     console.info(res)
 140   })
 141   .catch((err) => {
 142     console.error(err)
 143   })
 144 ```
 145
 146 You can do the same with the classes _ClusterWorker_, _FixedClusterPool_ and _DynamicClusterPool_.
 147
 148 **See [examples](./examples/) for more details**:
 149
 150 - [Javascript](./examples/javascript/)
 151 - [Typescript](./examples/typescript/)
 152   - [HTTP client pool](./examples/typescript/http-client-pool/)
 153   - [SMTP client pool](./examples/typescript/smtp-client-pool/)
 154   - [HTTP server pool](./examples/typescript/http-server-pool/)
 155     - [Express worker_threads pool](./examples/typescript/http-server-pool/express-worker_threads/)
 156     - [Express cluster pool](./examples/typescript/http-server-pool/express-cluster/)
 157     - [Express hybrid pool](./examples/typescript/http-server-pool/express-hybrid/)
 158     - [Fastify worker_threads pool](./examples/typescript/http-server-pool/fastify-worker_threads/)
 159     - [Fastify cluster pool](./examples/typescript/http-server-pool/fastify-cluster/)
 160     - [Fastify hybrid pool](./examples/typescript/http-server-pool/fastify-hybrid/)
 161   - [WebSocket server pool](./examples/typescript/websocket-server-pool/)
 162     - [ws worker_threads pool](./examples/typescript/websocket-server-pool/ws-worker_threads/)
 163     - [ws cluster pool](./examples/typescript/websocket-server-pool/ws-cluster/)
 164     - [ws hybrid pool](./examples/typescript/websocket-server-pool/ws-hybrid/)
 165
 166 Remember that workers can only send and receive structured-cloneable data.
 167
 168 ## Node.js versions
 169
 170 Node.js versions >= 16.14.x are supported.
 171
 172 ## [API](./docs/api.md)
 173
 174 ## [General guidelines](./docs/general-guidelines.md)
 175
 176 ## [Worker choice strategies](./docs/worker-choice-strategies.md)
 177
 178 ## Contribute
 179
 180 Choose your task here [2.6.x](https://github.com/orgs/poolifier/projects/1), propose an idea, a fix, an improvement.
 181
 182 See [CONTRIBUTING](CONTRIBUTING.md) guidelines.
 183
 184 ## Team
 185
 186 **Creator/Owner:**
 187
 188 - [**Alessandro Pio Ardizio**](https://github.com/pioardi)
 189
 190 **_Contributors_**
 191
 192 - [**Shinigami92**](https://github.com/Shinigami92)
 193 - [**Jérôme Benoit**](https://github.com/jerome-benoit)
 194
 195 ## License
 196
 197 [MIT](./LICENSE)