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 - Fixed and dynamic pool size :white_check_mark:
  39 - Easy switch from a pool type to another :white_check_mark:
  40 - Performance [benchmarks](./benchmarks/README.md) :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   - Task stealing :white_check_mark:
  51   - Tasks stealing under back pressure :white_check_mark:
  52   - Tasks redistribution on worker error :white_check_mark:
  53 - General guidelines on pool choice :white_check_mark:
  54 - Error handling out of the box :white_check_mark:
  55 - Widely tested :white_check_mark:
  56 - Active community :white_check_mark:
  57 - 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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  64
  65 ## Table of contents
  66
  67 - [Overview](#overview)
  68 - [Installation](#installation)
  69 - [Usage](#usage)
  70 - [Node.js versions](#nodejs-versions)
  71 - [API](#api)
  72 - [General guidelines](#general-guidelines)
  73 - [Worker choice strategies](#worker-choice-strategies)
  74 - [Contribute](#contribute)
  75 - [Team](#team)
  76 - [License](#license)
  77
  78 ## Overview
  79
  80 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.
  81 The first implementation is a fixed worker pool, with a defined number of workers that are started at creation time and will be reused.
  82 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 newly created workers will be stopped after a configurable period of inactivity.
  83 You have to implement your worker by extending the _ThreadWorker_ or _ClusterWorker_ class.
  84
  85 ## Installation
  86
  87 ```shell
  88 npm install poolifier --save
  89 ```
  90
  91 ## Usage
  92
  93 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_:
  94
  95 ```js
  96 'use strict'
  97 const { ThreadWorker } = require('poolifier')
  98
  99 function yourFunction(data) {
 100   // this will be executed in the worker thread,
 101   // the data will be received by using the execute method
 102   return { ok: 1 }
 103 }
 104
 105 module.exports = new ThreadWorker(yourFunction, {
 106   maxInactiveTime: 60000
 107 })
 108 ```
 109
 110 Instantiate your pool based on your needs :
 111
 112 ```js
 113 'use strict'
 114 const { DynamicThreadPool, FixedThreadPool, PoolEvents, availableParallelism } = require('poolifier')
 115
 116 // a fixed worker_threads pool
 117 const pool = new FixedThreadPool(availableParallelism(), './yourWorker.js', {
 118   errorHandler: (e) => console.error(e),
 119   onlineHandler: () => console.info('worker is online')
 120 })
 121
 122 pool.emitter.on(PoolEvents.ready, () => console.info('Pool is ready'))
 123 pool.emitter.on(PoolEvents.busy, () => console.info('Pool is busy'))
 124
 125 // or a dynamic worker_threads pool
 126 const pool = new DynamicThreadPool(Math.floor(availableParallelism() / 2), availableParallelism(), './yourWorker.js', {
 127   errorHandler: (e) => console.error(e),
 128   onlineHandler: () => console.info('worker is online')
 129 })
 130
 131 pool.emitter.on(PoolEvents.full, () => console.info('Pool is full'))
 132 pool.emitter.on(PoolEvents.ready, () => console.info('Pool is ready'))
 133 pool.emitter.on(PoolEvents.busy, () => console.info('Pool is busy'))
 134
 135 // the execute method signature is the same for both implementations,
 136 // so you can easily switch from one to another
 137 pool
 138   .execute()
 139   .then((res) => {
 140     console.info(res)
 141   })
 142   .catch((err) => {
 143     console.error(err)
 144   })
 145 ```
 146
 147 You can do the same with the classes _ClusterWorker_, _FixedClusterPool_ and _DynamicClusterPool_.
 148
 149 **See [examples](./examples/) for more details**:
 150
 151 - [Javascript](./examples/javascript/)
 152 - [Typescript](./examples/typescript/)
 153   - [HTTP client pool](./examples/typescript/http-client-pool/)
 154   - [SMTP client pool](./examples/typescript/smtp-client-pool/)
 155   - [HTTP server pool](./examples/typescript/http-server-pool/)
 156     - [Express worker_threads pool](./examples/typescript/http-server-pool/express-worker_threads/)
 157     - [Express cluster pool](./examples/typescript/http-server-pool/express-cluster/)
 158     - [Express hybrid pool](./examples/typescript/http-server-pool/express-hybrid/)
 159     - [Fastify worker_threads pool](./examples/typescript/http-server-pool/fastify-worker_threads/)
 160     - [Fastify cluster pool](./examples/typescript/http-server-pool/fastify-cluster/)
 161     - [Fastify hybrid pool](./examples/typescript/http-server-pool/fastify-hybrid/)
 162   - [WebSocket server pool](./examples/typescript/websocket-server-pool/)
 163     - [ws worker_threads pool](./examples/typescript/websocket-server-pool/ws-worker_threads/)
 164     - [ws cluster pool](./examples/typescript/websocket-server-pool/ws-cluster/)
 165     - [ws hybrid pool](./examples/typescript/websocket-server-pool/ws-hybrid/)
 166
 167 Remember that workers can only send and receive structured-cloneable data.
 168
 169 ## Node.js versions
 170
 171 Node.js versions >= 16.14.x are supported.
 172
 173 ## [API](./docs/api.md)
 174
 175 ## [General guidelines](./docs/general-guidelines.md)
 176
 177 ## [Worker choice strategies](./docs/worker-choice-strategies.md)
 178
 179 ## Contribute
 180
 181 Choose your task [here](https://github.com/orgs/poolifier/projects/1), propose an idea, a fix, an improvement.
 182
 183 See [CONTRIBUTING](./CONTRIBUTING.md) guidelines.
 184
 185 ## Team
 186
 187 **Creator/Owner:**
 188
 189 - [**Alessandro Pio Ardizio**](https://github.com/pioardi)
 190
 191 **Maintainers:**
 192
 193 - [**Jérôme Benoit**](https://github.com/jerome-benoit)
 194
 195 **Contributors:**
 196
 197 - [**Shinigami92**](https://github.com/Shinigami92)
 198
 199 ## License
 200
 201 [MIT](./LICENSE)