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[poolifier.git] / README.md
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4
5 <h2 align="center">Node Thread Pool and Cluster Pool :arrow_double_up: :on:</h2>
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30 </p>
31
32 ## Why Poolifier?
33
34 Poolifier 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.
35 With poolifier you can improve your **performance** and resolve problems related to the event loop.
36 Moreover you can execute your tasks using an API designed to improve the **developer experience**.
37 Please consult our <a href="#general-guidance">general guidelines</a>
38
39 - Performance :racehorse: [benchmarks](./benchmarks/README.md)
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)
41 - Easy to use :couple:
42 - Easy switch from a pool to another, easy to tune :heavy_check_mark:
43 - Dynamic pool size :heavy_check_mark:
44 - No runtime dependencies :heavy_check_mark:
45 - Proper async integration with node async hooks :heavy_check_mark:
46 - Support for worker threads and cluster node modules :heavy_check_mark:
47 - Support sync and async tasks :heavy_check_mark:
48 - General guidance on pools to use :heavy_check_mark:
49 - Widely tested :heavy_check_mark:
50 - Error handling out of the box :heavy_check_mark:
51 - Active community :heavy_check_mark:
52 - Code quality :octocat: [![Bugs](https://sonarcloud.io/api/project_badges/measure?project=pioardi_poolifier&metric=bugs)](https://sonarcloud.io/dashboard?id=pioardi_poolifier)
53 [![Code Smells](https://sonarcloud.io/api/project_badges/measure?project=pioardi_poolifier&metric=code_smells)](https://sonarcloud.io/dashboard?id=pioardi_poolifier)
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58
59 ## Contents
60
61 <h3 align="center">
62 <a href="#overview">Overview</a>
63 <span> · </span>
64 <a href="#installation">Installation</a>
65 <span> · </span>
66 <a href="#usage">Usage</a>
67 <span> · </span>
68 <a href="#node-versions">Node versions</a>
69 <span> · </span>
70 <a href="#api">API</a>
71 <span> · </span>
72 <a href="#general-guidance">General guidance</a>
73 <span> · </span>
74 <a href="#contribute">Contribute</a>
75 <span> · </span>
76 <a href="#team">Team</a>
77 <span> · </span>
78 <a href="#license">License</a>
79 </h3>
80
81 ## Overview
82
83 Node 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.
84 The first implementation is a static worker pool, with a defined number of workers that are started at creation time and will be reused.
85 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.
86 You have to implement your worker extending the ThreadWorker or ClusterWorker class
87
88 ## Installation
89
90 ```shell
91 npm install poolifier --save
92 ```
93
94 ## Usage
95
96 You can implement a worker-threads worker in a simple way by extending the class ThreadWorker:
97
98 ```js
99 'use strict'
100 const { ThreadWorker } = require('poolifier')
101
102 function yourFunction (data) {
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
108 module.exports = new ThreadWorker(yourFunction, {
109 maxInactiveTime: 60000,
110 async: false
111 })
112 ```
113
114 Instantiate your pool based on your needed :
115
116 ```js
117 'use strict'
118 const { FixedThreadPool, DynamicThreadPool } = require('poolifier')
119
120 // a fixed worker-threads pool
121 const pool = new FixedThreadPool(15,
122 './yourWorker.js',
123 { errorHandler: (e) => console.error(e), onlineHandler: () => console.log('worker is online') })
124
125 // or a dynamic worker-threads pool
126 const pool = new DynamicThreadPool(10, 100,
127 './yourWorker.js',
128 { errorHandler: (e) => console.error(e), onlineHandler: () => console.log('worker is online') })
129
130 pool.emitter.on('busy', () => console.log('Pool is busy'))
131
132 // the execute method signature is the same for both implementations,
133 // so you can easy switch from one to another
134 pool.execute({}).then(res => {
135 console.log(res)
136 }).catch ....
137
138 ```
139
140 You can do the same with the classes ClusterWorker, FixedClusterPool and DynamicClusterPool.
141
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**.
144
145 Remember that workers can only send and receive serializable data.
146
147 ## Node versions
148
149 You can use node versions 12.x, 13.x, 14.x, 16.x
150
151 ## API
152
153 ### `pool = new FixedThreadPool/FixedClusterPool(numberOfThreads/numberOfWorkers, filePath, opts)`
154
155 `numberOfThreads/numberOfWorkers` (mandatory) Number of workers for this pool
156 `filePath` (mandatory) Path to a file with a worker implementation
157 `opts` (optional) An object with these properties:
158
159 - `errorHandler` (optional) - A function that will listen for error event on each worker
160 - `onlineHandler` (optional) - A function that will listen for online event on each worker
161 - `exitHandler` (optional) - A function that will listen for exit event on each worker
162 - `workerChoiceStrategy` (optional) - The work choice strategy to use in this pool:
163
164 - `WorkerChoiceStrategies.ROUND_ROBIN`: Submit tasks to worker in this pool in a round robbin fashion
165 - `WorkerChoiceStrategies.LESS_RECENTLY_USED`: Submit tasks to the less recently used worker in the pool
166
167 Default: `WorkerChoiceStrategies.ROUND_ROBIN`
168
169 - `enableEvents` (optional) - Events emission enablement in this pool. Default: true
170
171 ### `pool = new DynamicThreadPool/DynamicClusterPool(min, max, filePath, opts)`
172
173 `min` (mandatory) Same as FixedThreadPool/FixedClusterPool numberOfThreads/numberOfWorkers, this number of workers will be always active
174 `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).
175 `filePath` (mandatory) Same as FixedThreadPool/FixedClusterPool
176 `opts` (optional) Same as FixedThreadPool/FixedClusterPool
177
178 ### `pool.execute(data)`
179
180 Execute method is available on both pool implementations (return type: Promise):
181 `data` (mandatory) An object that you want to pass to your worker implementation
182
183 ### `pool.destroy()`
184
185 Destroy method is available on both pool implementations.
186 This method will call the terminate method on each worker.
187
188 ### `class YourWorker extends ThreadWorker/ClusterWorker`
189
190 `fn` (mandatory) The function that you want to execute on the worker
191 `opts` (optional) An object with these properties:
192
193 - `maxInactiveTime` - Max time to wait tasks to work on (in ms), after this period the new worker will die.
194 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.
195 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.
196 If `killBehavior` is set to `KillBehaviors.SOFT` your tasks have no timeout and your workers will not be terminated until your task is completed.
197 Default: 60.000 ms
198
199 - `async` - true/false, true if your function contains async pieces else false
200 - `killBehavior` - Dictates if your async unit (worker/process) will be deleted in case that a task is active on it.
201 **KillBehaviors.SOFT**: If `currentTime - lastActiveTime` is greater than `maxInactiveTime` but a task is still running, then the worker **won't** be deleted.
202 **KillBehaviors.HARD**: If `lastActiveTime` is greater than `maxInactiveTime` but a task is still running, then the worker will be deleted.
203 This option only apply to the newly created workers.
204 Default: `KillBehaviors.SOFT`
205
206 ## General guidance
207
208 Performance is one of the main target of these worker pool implementations, we want to have a strong focus on this.
209 We already have a bench folder where you can find some comparisons.
210
211 ### Internal Node.js thread pool
212
213 Before 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.
214 Please 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).
215
216 **If your task runs on libuv thread pool**, you can try to:
217
218 - Tune the libuv thread pool size setting the [UV_THREADPOOL_SIZE](https://nodejs.org/api/cli.html#cli_uv_threadpool_size_size)
219
220 and/or
221
222 - 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.**
223
224 ### Cluster vs Threads worker pools
225
226 **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.
227 Thread pools are built on top of Node.js [worker-threads](https://nodejs.org/api/worker_threads.html#worker_threads_worker_threads) module.
228
229 **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.
230 Consider that by default Node.js already has great performance for I/O tasks (asynchronous I/O).
231 Cluster pools are built on top of Node.js [cluster](https://nodejs.org/api/cluster.html) module.
232
233 If 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).
234 But in general, **always profile your application**
235
236 ### Fixed vs Dynamic pools
237
238 To 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.
239 Increasing the memory footprint, your application will be ready to accept more tasks, but during idle time your application will consume more memory.
240 One 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.
241 For 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.
242 But in general, **always profile your application**
243
244 ## Contribute
245
246 See guidelines [CONTRIBUTING](CONTRIBUTING.md)
247 Choose your task here [2.0.0](https://github.com/poolifier/poolifier/projects/1), propose an idea, a fix, an improvement.
248
249 ## Team
250
251 <!-- ALL-CONTRIBUTORS-LIST:START - Do not remove or modify this section -->
252 <!-- prettier-ignore-start -->
253 <!-- markdownlint-disable -->
254
255 **Creator/Owner:**
256
257 - [**Alessandro Pio Ardizio**](https://github.com/pioardi)
258
259 **_Contributors_**
260
261 - [**Shinigami92**](https://github.com/Shinigami92)
262 - [**Jérôme Benoit**](https://github.com/jerome-benoit)
263
264 ## License
265
266 [MIT](./LICENSE)