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 task functions CRUD operations at runtime :white_check_mark:
  47 - Support for sync and async task functions :white_check_mark:
  48 - Tasks distribution strategies :white_check_mark:
  49 - Lockless tasks queueing :white_check_mark:
  50 - Queued tasks rescheduling:
  51   - Task stealing :white_check_mark:
  52   - Tasks stealing under back pressure :white_check_mark:
  53   - Tasks redistribution on worker error :white_check_mark:
  54 - General guidelines on pool choice :white_check_mark:
  55 - Error handling out of the box :white_check_mark:
  56 - Widely tested :white_check_mark:
  57 - Active community :white_check_mark:
  58 - 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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  65
  66 ## Table of contents
  67
  68 - [Overview](#overview)
  69 - [Installation](#installation)
  70 - [Usage](#usage)
  71 - [Node.js versions](#nodejs-versions)
  72 - [API](#api)
  73 - [General guidelines](#general-guidelines)
  74 - [Worker choice strategies](#worker-choice-strategies)
  75 - [Contribute](#contribute)
  76 - [Team](#team)
  77 - [License](#license)
  78
  79 ## Overview
  80
  81 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.
  82 The first implementation is a fixed worker pool, with a defined number of workers that are started at creation time and will be reused.
  83 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.
  84 You have to implement your worker by extending the _ThreadWorker_ or _ClusterWorker_ class.
  85
  86 ## Installation
  87
  88 ```shell
  89 npm install poolifier --save
  90 ```
  91
  92 ## Usage
  93
  94 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_:
  95
  96 ```js
  97 'use strict'
  98 const { ThreadWorker } = require('poolifier')
  99
 100 function yourFunction(data) {
 101   // this will be executed in the worker thread,
 102   // the data will be received by using the execute method
 103   return { ok: 1 }
 104 }
 105
 106 module.exports = new ThreadWorker(yourFunction, {
 107   maxInactiveTime: 60000
 108 })
 109 ```
 110
 111 Instantiate your pool based on your needs :
 112
 113 ```js
 114 'use strict'
 115 const { DynamicThreadPool, FixedThreadPool, PoolEvents, availableParallelism } = require('poolifier')
 116
 117 // a fixed worker_threads pool
 118 const pool = new FixedThreadPool(availableParallelism(), './yourWorker.js', {
 119   errorHandler: (e) => console.error(e),
 120   onlineHandler: () => console.info('worker is online')
 121 })
 122
 123 pool.emitter.on(PoolEvents.ready, () => console.info('Pool is ready'))
 124 pool.emitter.on(PoolEvents.busy, () => console.info('Pool is busy'))
 125
 126 // or a dynamic worker_threads pool
 127 const pool = new DynamicThreadPool(Math.floor(availableParallelism() / 2), availableParallelism(), './yourWorker.js', {
 128   errorHandler: (e) => console.error(e),
 129   onlineHandler: () => console.info('worker is online')
 130 })
 131
 132 pool.emitter.on(PoolEvents.full, () => console.info('Pool is full'))
 133 pool.emitter.on(PoolEvents.ready, () => console.info('Pool is ready'))
 134 pool.emitter.on(PoolEvents.busy, () => console.info('Pool is busy'))
 135
 136 // the execute method signature is the same for both implementations,
 137 // so you can easily switch from one to another
 138 pool
 139   .execute()
 140   .then((res) => {
 141     console.info(res)
 142   })
 143   .catch((err) => {
 144     console.error(err)
 145   })
 146 ```
 147
 148 You can do the same with the classes _ClusterWorker_, _FixedClusterPool_ and _DynamicClusterPool_.
 149
 150 **See [examples](./examples/) for more details**:
 151
 152 - [Javascript](./examples/javascript/)
 153 - [Typescript](./examples/typescript/)
 154   - [HTTP client pool](./examples/typescript/http-client-pool/)
 155   - [SMTP client pool](./examples/typescript/smtp-client-pool/)
 156   - [HTTP server pool](./examples/typescript/http-server-pool/)
 157     - [Express worker_threads pool](./examples/typescript/http-server-pool/express-worker_threads/)
 158     - [Express cluster pool](./examples/typescript/http-server-pool/express-cluster/)
 159     - [Express hybrid pool](./examples/typescript/http-server-pool/express-hybrid/)
 160     - [Fastify worker_threads pool](./examples/typescript/http-server-pool/fastify-worker_threads/)
 161     - [Fastify cluster pool](./examples/typescript/http-server-pool/fastify-cluster/)
 162     - [Fastify hybrid pool](./examples/typescript/http-server-pool/fastify-hybrid/)
 163   - [WebSocket server pool](./examples/typescript/websocket-server-pool/)
 164     - [ws worker_threads pool](./examples/typescript/websocket-server-pool/ws-worker_threads/)
 165     - [ws cluster pool](./examples/typescript/websocket-server-pool/ws-cluster/)
 166     - [ws hybrid pool](./examples/typescript/websocket-server-pool/ws-hybrid/)
 167
 168 Remember that workers can only send and receive structured-cloneable data.
 169
 170 ## Node.js versions
 171
 172 Node.js versions >= 16.14.x are supported.
 173
 174 ## [API](./docs/api.md)
 175
 176 ## [General guidelines](./docs/general-guidelines.md)
 177
 178 ## [Worker choice strategies](./docs/worker-choice-strategies.md)
 179
 180 ## Contribute
 181
 182 Choose your task [here](https://github.com/orgs/poolifier/projects/1), propose an idea, a fix, an improvement.
 183
 184 See [CONTRIBUTING](./CONTRIBUTING.md) guidelines.
 185
 186 ## Team
 187
 188 **Creator/Owner:**
 189
 190 - [**Alessandro Pio Ardizio**](https://github.com/pioardi)
 191
 192 **Maintainers:**
 193
 194 - [**Jérôme Benoit**](https://github.com/jerome-benoit)
 195
 196 **Contributors:**
 197
 198 - [**Shinigami92**](https://github.com/Shinigami92)
 199
 200 ## License
 201
 202 [MIT](./LICENSE)