perf: remove unneeded class indirection for dynamic pool in worker
[poolifier.git] / README.md
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063f8c5b 5<h2 align="center">Node Thread Pool and Cluster Pool :arrow_double_up: :on:</h2>
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7<p align="center">
8 <a href="https://www.npmjs.com/package/poolifier">
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28</p>
29
74750c7f 30## Why Poolifier?
e76f5485 31
c868b39b 32Poolifier 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 33With poolifier you can improve your **performance** and resolve problems related to the event loop.
063f8c5b 34Moreover you can execute your tasks using an API designed to improve the **developer experience**.
e36cfb13 35Please consult our <a href="#general-guidance">general guidelines</a>
e76f5485 36
64060857 37- Performance :racehorse: [benchmarks](./benchmarks/README.md)
f2b5671a 38- 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 39- Easy to use :couple:
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40- Easy switch from a pool to another, easy to tune :white_check_mark:
41- Dynamic pool size :white_check_mark:
42- No runtime dependencies :white_check_mark:
43- Proper async integration with node async hooks :white_check_mark:
44- Support for worker threads and cluster node modules :white_check_mark:
45- Support sync and async tasks :white_check_mark:
46- General guidance on pools to use :white_check_mark:
47- Widely tested :white_check_mark:
48- Error handling out of the box :white_check_mark:
49- Active community :white_check_mark:
5fd75a2e 50- 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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ddaa3a76 56
50aa7901 57## Contents
e76f5485 58
34a572eb 59<h3 align="center">
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60 <a href="#overview">Overview</a>
61 <span> · </span>
34a572eb 62 <a href="#installation">Installation</a>
63 <span> · </span>
64 <a href="#usage">Usage</a>
65 <span> · </span>
4f4ae1cb 66 <a href="#node-versions">Node versions</a>
50aa7901 67 <span> · </span>
34a572eb 68 <a href="#api">API</a>
69 <span> · </span>
e36cfb13 70 <a href="#general-guidance">General guidance</a>
48211d04 71 <span> · </span>
34a572eb 72 <a href="#contribute">Contribute</a>
73 <span> · </span>
50aa7901 74 <a href="#team">Team</a>
34a572eb 75 <span> · </span>
76 <a href="#license">License</a>
77</h3>
78
50aa7901 79## Overview
13031992 80
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81Node 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.
82The first implementation is a static worker pool, with a defined number of workers that are started at creation time and will be reused.
83The 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.
84You have to implement your worker extending the ThreadWorker or ClusterWorker class
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85
86## Installation
87
88```shell
27c5fb75 89npm install poolifier --save
1a4ec243 90```
1a4ec243 91
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92## Usage
93
31b90205 94You can implement a worker-threads worker in a simple way by extending the class ThreadWorker:
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95
96```js
97'use strict'
d2eb4964 98const { ThreadWorker } = require('poolifier')
1a4ec243 99
78cea37e 100function yourFunction(data) {
106744f7 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
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106module.exports = new ThreadWorker(yourFunction, {
107 maxInactiveTime: 60000,
108 async: false
109})
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110```
111
1f9a5a44 112Instantiate your pool based on your needed :
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113
114```js
115'use strict'
d2eb4964 116const { FixedThreadPool, DynamicThreadPool } = require('poolifier')
1a4ec243 117
31b90205 118// a fixed worker-threads pool
1a4ec243 119const pool = new FixedThreadPool(15,
106744f7 120 './yourWorker.js',
121 { errorHandler: (e) => console.error(e), onlineHandler: () => console.log('worker is online') })
1a4ec243 122
31b90205 123// or a dynamic worker-threads pool
1a4ec243 124const pool = new DynamicThreadPool(10, 100,
106744f7 125 './yourWorker.js',
126 { errorHandler: (e) => console.error(e), onlineHandler: () => console.log('worker is online') })
127
a72f2599 128pool.emitter.on('busy', () => console.log('Pool is busy'))
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129
130// the execute method signature is the same for both implementations,
131// so you can easy switch from one to another
132pool.execute({}).then(res => {
133 console.log(res)
777b7824 134}).catch ....
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135
136```
137
17a9a094 138You can do the same with the classes ClusterWorker, FixedClusterPool and DynamicClusterPool.
31b90205 139
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140**See examples folder for more details (in particular if you want to use a pool for [multiple functions](./examples/multiFunctionExample.js)).**
141**Now TypeScript is also supported, find how to use it into the example folder**.
1a4ec243 142
ec2ccfc8 143Remember that workers can only send and receive serializable data.
deb85c12 144
50aa7901 145## Node versions
34a572eb 146
767d1512 147Node versions >= 16.x are supported.
1a4ec243 148
50aa7901 149## API
34a572eb 150
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151### [Documentation](https://poolifier.github.io/poolifier/)
152
31b90205 153### `pool = new FixedThreadPool/FixedClusterPool(numberOfThreads/numberOfWorkers, filePath, opts)`
50aa7901 154
f42ca86f 155`numberOfThreads/numberOfWorkers` (mandatory) Number of workers for this pool
50aa7901 156`filePath` (mandatory) Path to a file with a worker implementation
f42ca86f 157`opts` (optional) An object with these properties:
50aa7901 158
46e857ca 159- `messageHandler` (optional) - A function that will listen for message event on each worker
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160- `errorHandler` (optional) - A function that will listen for error event on each worker
161- `onlineHandler` (optional) - A function that will listen for online event on each worker
162- `exitHandler` (optional) - A function that will listen for exit event on each worker
46e857ca 163- `workerChoiceStrategy` (optional) - The worker choice strategy to use in this pool:
5519f8f3 164
46e857ca 165 - `WorkerChoiceStrategies.ROUND_ROBIN`: Submit tasks to worker in a round robbin fashion
737c6d97 166 - `WorkerChoiceStrategies.LESS_USED`: Submit tasks to the less used worker
168c526f 167 - `WorkerChoiceStrategies.LESS_BUSY`: Submit tasks to the less busy worker
cb9eb085 168 - `WorkerChoiceStrategies.WEIGHTED_ROUND_ROBIN`: Submit tasks to worker using a weighted round robin scheduling algorithm based on tasks execution time
46e857ca 169 - `WorkerChoiceStrategies.FAIR_SHARE`: Submit tasks to worker using a fair share tasks scheduling algorithm based on tasks execution time
5519f8f3 170
cb5d2427 171 `WorkerChoiceStrategies.WEIGHTED_ROUND_ROBIN` and `WorkerChoiceStrategies.FAIR_SHARE` strategies are targeted to heavy and long tasks
f42ca86f 172 Default: `WorkerChoiceStrategies.ROUND_ROBIN`
5519f8f3 173
f42ca86f 174- `enableEvents` (optional) - Events emission enablement in this pool. Default: true
34a572eb 175
31b90205 176### `pool = new DynamicThreadPool/DynamicClusterPool(min, max, filePath, opts)`
50aa7901 177
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178`min` (mandatory) Same as FixedThreadPool/FixedClusterPool numberOfThreads/numberOfWorkers, this number of workers will be always active
179`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).
180`filePath` (mandatory) Same as FixedThreadPool/FixedClusterPool
181`opts` (optional) Same as FixedThreadPool/FixedClusterPool
34a572eb 182
183### `pool.execute(data)`
50aa7901 184
f42ca86f 185Execute method is available on both pool implementations (return type: Promise):
50aa7901 186`data` (mandatory) An object that you want to pass to your worker implementation
34a572eb 187
188### `pool.destroy()`
34a572eb 189
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190Destroy method is available on both pool implementations.
191This method will call the terminate method on each worker.
34a572eb 192
31b90205 193### `class YourWorker extends ThreadWorker/ClusterWorker`
50aa7901 194
31b90205 195`fn` (mandatory) The function that you want to execute on the worker
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196`opts` (optional) An object with these properties:
197
31b90205 198- `maxInactiveTime` - Max time to wait tasks to work on (in ms), after this period the new worker will die.
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199 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.
200 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.
201 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 202 Default: 60000 ms
15eacd5d 203
46e857ca 204- `async` - true/false, true if your function contains async code pieces, else false
15eacd5d 205- `killBehavior` - Dictates if your async unit (worker/process) will be deleted in case that a task is active on it.
f42ca86f 206 **KillBehaviors.SOFT**: If `currentTime - lastActiveTime` is greater than `maxInactiveTime` but a task is still running, then the worker **won't** be deleted.
a9d9ea34 207 **KillBehaviors.HARD**: If `currentTime - lastActiveTime` is greater than `maxInactiveTime` but a task is still running, then the worker will be deleted.
3832ad95 208 This option only apply to the newly created workers.
f42ca86f 209 Default: `KillBehaviors.SOFT`
50aa7901 210
e36cfb13 211## General guidance
34a572eb 212
31b90205 213Performance is one of the main target of these worker pool implementations, we want to have a strong focus on this.
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214We already have a bench folder where you can find some comparisons.
215
216### Internal Node.js thread pool
217
218Before 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.
219Please 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).
220
e843b904 221**If your task runs on libuv thread pool**, you can try to:
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222
223- Tune the libuv thread pool size setting the [UV_THREADPOOL_SIZE](https://nodejs.org/api/cli.html#cli_uv_threadpool_size_size)
224
225and/or
226
227- 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.**
228
229### Cluster vs Threads worker pools
230
231**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 232Thread pools are built on top of Node.js [worker-threads](https://nodejs.org/api/worker_threads.html#worker_threads_worker_threads) module.
233
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234**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.
235Consider that by default Node.js already has great performance for I/O tasks (asynchronous I/O).
4a6952ff 236Cluster pools are built on top of Node.js [cluster](https://nodejs.org/api/cluster.html) module.
75876e4c 237
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238If 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).
239But in general, **always profile your application**
240
241### Fixed vs Dynamic pools
063f8c5b 242
31b90205 243To 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 244Increasing 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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245One 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.
246For 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 247But in general, **always profile your application**
48211d04 248
50aa7901 249## Contribute
34a572eb 250
50aa7901 251See guidelines [CONTRIBUTING](CONTRIBUTING.md)
d1affa4c 252Choose your task here [2.4.x](https://github.com/orgs/poolifier/projects/1), propose an idea, a fix, an improvement.
1a4ec243 253
50aa7901 254## Team
1a4ec243 255
39deb558 256<!-- ALL-CONTRIBUTORS-LIST:START - Do not remove or modify this section -->
39deb558 257
258**Creator/Owner:**
39deb558 259
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260- [**Alessandro Pio Ardizio**](https://github.com/pioardi)
261
262**_Contributors_**
263
264- [**Shinigami92**](https://github.com/Shinigami92)
265- [**Jérôme Benoit**](https://github.com/jerome-benoit)
39deb558 266
50aa7901 267## License
1a4ec243 268
9507c1d4 269[MIT](./LICENSE)