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063f8c5b 5<h2 align="center">Node Thread Pool and Cluster Pool :arrow_double_up: :on:</h2>
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9</h2>
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11<p align="center">
12 <a href="https://www.npmjs.com/package/poolifier">
13 <img alt="Weekly Downloads" src="https://img.shields.io/npm/dw/poolifier"></a>
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26 <a href="http://makeapullrequest.com">
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30</p>
31
74750c7f 32## Why Poolifier?
e76f5485 33
c868b39b 34Poolifier is used to perform CPU intensive and I/O intensive tasks on nodejs servers, it implements worker pools (yes, more worker 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) and cluster pools using [Node.js cluster](https://nodejs.org/api/cluster.html) modules.
50aa7901 35With poolifier you can improve your **performance** and resolve problems related to the event loop.
063f8c5b 36Moreover you can execute your tasks using an API designed to improve the **developer experience**.
e36cfb13 37Please consult our <a href="#general-guidance">general guidelines</a>
e76f5485 38
64060857 39- Performance :racehorse: [benchmarks](./benchmarks/README.md)
f2b5671a 40- 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)
b1b24f66 41- Easy to use :couple:
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42- Easy switch from a pool to another, easy to tune :white_check_mark:
43- Dynamic pool size :white_check_mark:
44- No runtime dependencies :white_check_mark:
45- Proper async integration with node async hooks :white_check_mark:
46- Support for worker threads and cluster node modules :white_check_mark:
47- Support sync and async tasks :white_check_mark:
48- General guidance on pools to use :white_check_mark:
49- Widely tested :white_check_mark:
50- Error handling out of the box :white_check_mark:
51- Active community :white_check_mark:
5fd75a2e 52- 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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53 [![Code Smells](https://sonarcloud.io/api/project_badges/measure?project=pioardi_poolifier&metric=code_smells)](https://sonarcloud.io/dashboard?id=pioardi_poolifier)
54 [![Duplicated Lines (%)](https://sonarcloud.io/api/project_badges/measure?project=pioardi_poolifier&metric=duplicated_lines_density)](https://sonarcloud.io/dashboard?id=pioardi_poolifier)
55 [![Maintainability Rating](https://sonarcloud.io/api/project_badges/measure?project=pioardi_poolifier&metric=sqale_rating)](https://sonarcloud.io/dashboard?id=pioardi_poolifier)
56 [![Reliability Rating](https://sonarcloud.io/api/project_badges/measure?project=pioardi_poolifier&metric=reliability_rating)](https://sonarcloud.io/dashboard?id=pioardi_poolifier)
57 [![Technical Debt](https://sonarcloud.io/api/project_badges/measure?project=pioardi_poolifier&metric=sqale_index)](https://sonarcloud.io/dashboard?id=pioardi_poolifier)
ddaa3a76 58
50aa7901 59## Contents
e76f5485 60
34a572eb 61<h3 align="center">
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62 <a href="#overview">Overview</a>
63 <span> · </span>
34a572eb 64 <a href="#installation">Installation</a>
65 <span> · </span>
66 <a href="#usage">Usage</a>
67 <span> · </span>
4f4ae1cb 68 <a href="#node-versions">Node versions</a>
50aa7901 69 <span> · </span>
34a572eb 70 <a href="#api">API</a>
71 <span> · </span>
e36cfb13 72 <a href="#general-guidance">General guidance</a>
48211d04 73 <span> · </span>
34a572eb 74 <a href="#contribute">Contribute</a>
75 <span> · </span>
50aa7901 76 <a href="#team">Team</a>
34a572eb 77 <span> · </span>
78 <a href="#license">License</a>
79</h3>
80
50aa7901 81## Overview
13031992 82
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83Node pool contains two [worker-threads](https://nodejs.org/api/worker_threads.html#worker_threads_worker_threads)/[cluster worker](https://nodejs.org/api/cluster.html#cluster_class_worker) pool implementations, you don't have to deal with worker-threads/cluster worker complexity.
84The first implementation is a static worker pool, with a defined number of workers that are started at creation time and will be reused.
85The 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.
86You have to implement your worker extending the ThreadWorker or ClusterWorker class
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87
88## Installation
89
90```shell
27c5fb75 91npm install poolifier --save
1a4ec243 92```
1a4ec243 93
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94## Usage
95
31b90205 96You can implement a worker-threads worker in a simple way by extending the class ThreadWorker:
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97
98```js
99'use strict'
d2eb4964 100const { ThreadWorker } = require('poolifier')
1a4ec243 101
4a297cd5 102function yourFunction (data) {
106744f7 103 // this will be executed in the worker thread,
104 // the data will be received by using the execute method
105 return { ok: 1 }
106}
107
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108module.exports = new ThreadWorker(yourFunction, {
109 maxInactiveTime: 60000,
110 async: false
111})
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112```
113
1f9a5a44 114Instantiate your pool based on your needed :
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115
116```js
117'use strict'
d2eb4964 118const { FixedThreadPool, DynamicThreadPool } = require('poolifier')
1a4ec243 119
31b90205 120// a fixed worker-threads pool
1a4ec243 121const pool = new FixedThreadPool(15,
106744f7 122 './yourWorker.js',
123 { errorHandler: (e) => console.error(e), onlineHandler: () => console.log('worker is online') })
1a4ec243 124
31b90205 125// or a dynamic worker-threads pool
1a4ec243 126const pool = new DynamicThreadPool(10, 100,
106744f7 127 './yourWorker.js',
128 { errorHandler: (e) => console.error(e), onlineHandler: () => console.log('worker is online') })
129
a72f2599 130pool.emitter.on('busy', () => console.log('Pool is busy'))
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131
132// the execute method signature is the same for both implementations,
133// so you can easy switch from one to another
134pool.execute({}).then(res => {
135 console.log(res)
777b7824 136}).catch ....
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137
138```
139
17a9a094 140You can do the same with the classes ClusterWorker, FixedClusterPool and DynamicClusterPool.
31b90205 141
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142**See examples folder for more details (in particular if you want to use a pool for [multiple functions](./examples/multiFunctionExample.js)).**
143**Now TypeScript is also supported, find how to use it into the example folder**.
1a4ec243 144
ec2ccfc8 145Remember that workers can only send and receive serializable data.
deb85c12 146
50aa7901 147## Node versions
34a572eb 148
767d1512 149Node versions >= 16.x are supported.
1a4ec243 150
50aa7901 151## API
34a572eb 152
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153### [Documentation](https://poolifier.github.io/poolifier/)
154
31b90205 155### `pool = new FixedThreadPool/FixedClusterPool(numberOfThreads/numberOfWorkers, filePath, opts)`
50aa7901 156
f42ca86f 157`numberOfThreads/numberOfWorkers` (mandatory) Number of workers for this pool
50aa7901 158`filePath` (mandatory) Path to a file with a worker implementation
f42ca86f 159`opts` (optional) An object with these properties:
50aa7901 160
46e857ca 161- `messageHandler` (optional) - A function that will listen for message event on each worker
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162- `errorHandler` (optional) - A function that will listen for error event on each worker
163- `onlineHandler` (optional) - A function that will listen for online event on each worker
164- `exitHandler` (optional) - A function that will listen for exit event on each worker
46e857ca 165- `workerChoiceStrategy` (optional) - The worker choice strategy to use in this pool:
5519f8f3 166
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167 - `WorkerChoiceStrategies.ROUND_ROBIN`: Submit tasks to worker in a round robbin fashion
168 - `WorkerChoiceStrategies.LESS_RECENTLY_USED`: Submit tasks to the less recently used worker
169 - `WorkerChoiceStrategies.WEIGHTED_ROUND_ROBIN` Submit tasks to worker using a weighted round robin scheduling algorithm based on tasks execution time
170 - `WorkerChoiceStrategies.FAIR_SHARE`: Submit tasks to worker using a fair share tasks scheduling algorithm based on tasks execution time
5519f8f3 171
cb5d2427 172 `WorkerChoiceStrategies.WEIGHTED_ROUND_ROBIN` and `WorkerChoiceStrategies.FAIR_SHARE` strategies are targeted to heavy and long tasks
f42ca86f 173 Default: `WorkerChoiceStrategies.ROUND_ROBIN`
5519f8f3 174
f42ca86f 175- `enableEvents` (optional) - Events emission enablement in this pool. Default: true
34a572eb 176
31b90205 177### `pool = new DynamicThreadPool/DynamicClusterPool(min, max, filePath, opts)`
50aa7901 178
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179`min` (mandatory) Same as FixedThreadPool/FixedClusterPool numberOfThreads/numberOfWorkers, this number of workers will be always active
180`max` (mandatory) Max number of workers that this pool can contain, the new created workers will die after a threshold (default is 1 minute, you can override it in your worker implementation).
181`filePath` (mandatory) Same as FixedThreadPool/FixedClusterPool
182`opts` (optional) Same as FixedThreadPool/FixedClusterPool
34a572eb 183
184### `pool.execute(data)`
50aa7901 185
f42ca86f 186Execute method is available on both pool implementations (return type: Promise):
50aa7901 187`data` (mandatory) An object that you want to pass to your worker implementation
34a572eb 188
189### `pool.destroy()`
34a572eb 190
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191Destroy method is available on both pool implementations.
192This method will call the terminate method on each worker.
34a572eb 193
31b90205 194### `class YourWorker extends ThreadWorker/ClusterWorker`
50aa7901 195
31b90205 196`fn` (mandatory) The function that you want to execute on the worker
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197`opts` (optional) An object with these properties:
198
31b90205 199- `maxInactiveTime` - Max time to wait tasks to work on (in ms), after this period the new worker will die.
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200 The last active time of your worker unit will be updated when a task is submitted to a worker or when a worker terminate a task.
201 If `killBehavior` is set to `KillBehaviors.HARD` this value represents also the timeout for the tasks that you submit to the pool, when this timeout expires your tasks is interrupted and the worker is killed if is not part of the minimum size of the pool.
202 If `killBehavior` is set to `KillBehaviors.SOFT` your tasks have no timeout and your workers will not be terminated until your task is completed.
bf9549ae 203 Default: 60000 ms
15eacd5d 204
46e857ca 205- `async` - true/false, true if your function contains async code pieces, else false
15eacd5d 206- `killBehavior` - Dictates if your async unit (worker/process) will be deleted in case that a task is active on it.
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207 **KillBehaviors.SOFT**: If `currentTime - lastActiveTime` is greater than `maxInactiveTime` but a task is still running, then the worker **won't** be deleted.
208 **KillBehaviors.HARD**: If `lastActiveTime` is greater than `maxInactiveTime` but a task is still running, then the worker will be deleted.
3832ad95 209 This option only apply to the newly created workers.
f42ca86f 210 Default: `KillBehaviors.SOFT`
50aa7901 211
e36cfb13 212## General guidance
34a572eb 213
31b90205 214Performance is one of the main target of these worker pool implementations, we want to have a strong focus on this.
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215We already have a bench folder where you can find some comparisons.
216
217### Internal Node.js thread pool
218
219Before to jump into each poolifier pool type, let highlight that **Node.js comes with a thread pool already**, the libuv thread pool where some particular tasks already run by default.
220Please take a look at [which tasks run on the libuv thread pool](https://nodejs.org/en/docs/guides/dont-block-the-event-loop/#what-code-runs-on-the-worker-pool).
221
e843b904 222**If your task runs on libuv thread pool**, you can try to:
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223
224- Tune the libuv thread pool size setting the [UV_THREADPOOL_SIZE](https://nodejs.org/api/cli.html#cli_uv_threadpool_size_size)
225
226and/or
227
228- Use poolifier cluster pool that spawning child processes will also increase the number of libuv threads since that any new child process comes with a separated libuv thread pool. **More threads does not mean more fast, so please tune your application.**
229
230### Cluster vs Threads worker pools
231
232**If your task does not run into libuv thread pool** and is CPU intensive then poolifier **thread pools** (FixedThreadPool and DynamicThreadPool) are suggested to run CPU intensive tasks, you can still run I/O intensive tasks into thread pools, but performance enhancement is expected to be minimal.
063f8c5b 233Thread pools are built on top of Node.js [worker-threads](https://nodejs.org/api/worker_threads.html#worker_threads_worker_threads) module.
234
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235**If your task does not run into libuv thread pool** and is I/O intensive then poolifier **cluster pools** (FixedClusterPool and DynamicClusterPool) are suggested to run I/O intensive tasks, again you can still run CPU intensive tasks into cluster pools, but performance enhancement is expected to be minimal.
236Consider that by default Node.js already has great performance for I/O tasks (asynchronous I/O).
4a6952ff 237Cluster pools are built on top of Node.js [cluster](https://nodejs.org/api/cluster.html) module.
75876e4c 238
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239If your task contains code that runs on libuv plus code that is CPU intensive or I/O intensive you either split it either combine more strategies (i.e. tune the number of libuv threads and use cluster/thread pools).
240But in general, **always profile your application**
241
242### Fixed vs Dynamic pools
063f8c5b 243
31b90205 244To choose your pool consider that with a FixedThreadPool/FixedClusterPool or a DynamicThreadPool/DynamicClusterPool (in this case is important the min parameter passed to the constructor) your application memory footprint will increase.
063f8c5b 245Increasing the memory footprint, your application will be ready to accept more tasks, but during idle time your application will consume more memory.
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246One good choose from my point of view is to profile your application using Fixed/Dynamic worker pool, and to see your application metrics when you increase/decrease the num of workers.
247For example you could keep the memory footprint low choosing a DynamicThreadPool/DynamicClusterPool with 5 workers, and allow to create new workers until 50/100 when needed, this is the advantage to use the DynamicThreadPool/DynamicClusterPool.
50aa7901 248But in general, **always profile your application**
48211d04 249
50aa7901 250## Contribute
34a572eb 251
50aa7901 252See guidelines [CONTRIBUTING](CONTRIBUTING.md)
865769d5 253Choose your task here [2.3.x](https://github.com/orgs/poolifier/projects/1), propose an idea, a fix, an improvement.
1a4ec243 254
50aa7901 255## Team
1a4ec243 256
39deb558 257<!-- ALL-CONTRIBUTORS-LIST:START - Do not remove or modify this section -->
39deb558 258
259**Creator/Owner:**
39deb558 260
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261- [**Alessandro Pio Ardizio**](https://github.com/pioardi)
262
263**_Contributors_**
264
265- [**Shinigami92**](https://github.com/Shinigami92)
266- [**Jérôme Benoit**](https://github.com/jerome-benoit)
39deb558 267
50aa7901 268## License
1a4ec243 269
9507c1d4 270[MIT](./LICENSE)