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987e0026 | 1 | # Node Thread Pool :arrow_double_up: :on: |
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8 | )](https://img.shields.io/static/v1?label=dependencies&message=no%20dependencies&color=brightgreen | |
9 | ) | |
b4b2dc8b | 10 | |
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11 | <h2>Why Poolifier? </h2> |
12 | Poolifier is used to perform heavy CPU bound tasks on nodejs servers, it implements a thread pool using <a href="https://nodejs.org/api/worker_threads.html#worker_threads_worker_threads">worker-threads </a>. | |
13 | With poolifier you can improve your performance and resolve problems related to the event loop.<br> | |
14 | ||
15 | ||
16 | ||
34a572eb | 17 | <h2>Contents </h2> |
18 | <h3 align="center"> | |
19 | <a href="#installation">Installation</a> | |
20 | <span> · </span> | |
21 | <a href="#usage">Usage</a> | |
22 | <span> · </span> | |
23 | <a href="#api">API</a> | |
24 | <span> · </span> | |
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25 | <a href="#cyp">Choose a pool</a> |
26 | <span> · </span> | |
34a572eb | 27 | <a href="#contribute">Contribute</a> |
28 | <span> · </span> | |
29 | <a href="#nv">Compatibility</a> | |
30 | <span> · </span> | |
31 | <a href="#license">License</a> | |
32 | </h3> | |
33 | ||
f349ea72 | 34 | <h2> Overview </h2> |
1a4ec243 | 35 | Node pool contains two <a href="https://nodejs.org/api/worker_threads.html#worker_threads_worker_threads">worker-threads </a> pool implementations , you don' t have to deal with worker-threads complexity. <br> |
755f08b3 | 36 | The first implementation is a static thread pool , with a defined number of threads that are started at creation time and will be reused.<br> |
106744f7 | 37 | The second implementation is a dynamic thread pool with a number of threads started at creation time ( these threads will be always active and reused) and other threads created when the load will increase ( with an upper limit, these threads will be reused when active ), the new created threads will be stopped after a configurable period of inactivity. <br> |
34a572eb | 38 | You have to implement your worker extending the ThreadWorker class<br> |
39 | <h2 id="installation">Installation</h2> | |
13031992 | 40 | |
1a4ec243 | 41 | ``` |
27c5fb75 | 42 | npm install poolifier --save |
1a4ec243 | 43 | ``` |
34a572eb | 44 | <h2 id="usage">Usage</h2> |
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45 | |
46 | You can implement a worker in a simple way , extending the class ThreadWorker : | |
47 | ||
48 | ```js | |
49 | 'use strict' | |
d2eb4964 | 50 | const { ThreadWorker } = require('poolifier') |
1a4ec243 | 51 | |
106744f7 | 52 | function yourFunction (data) { |
53 | // this will be executed in the worker thread, | |
54 | // the data will be received by using the execute method | |
55 | return { ok: 1 } | |
56 | } | |
57 | ||
1f9a5a44 | 58 | module.exports = new ThreadWorker(yourFunction, { maxInactiveTime: 60000 }) |
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59 | ``` |
60 | ||
1f9a5a44 | 61 | Instantiate your pool based on your needed : |
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62 | |
63 | ```js | |
64 | 'use strict' | |
d2eb4964 | 65 | const { FixedThreadPool, DynamicThreadPool } = require('poolifier') |
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66 | |
67 | // a fixed thread pool | |
68 | const pool = new FixedThreadPool(15, | |
106744f7 | 69 | './yourWorker.js', |
70 | { errorHandler: (e) => console.error(e), onlineHandler: () => console.log('worker is online') }) | |
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71 | |
72 | // or a dynamic thread pool | |
73 | const pool = new DynamicThreadPool(10, 100, | |
106744f7 | 74 | './yourWorker.js', |
75 | { errorHandler: (e) => console.error(e), onlineHandler: () => console.log('worker is online') }) | |
76 | ||
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77 | pool.emitter.on('FullPool', () => console.log('Pool is full')) |
78 | ||
79 | // the execute method signature is the same for both implementations, | |
80 | // so you can easy switch from one to another | |
81 | pool.execute({}).then(res => { | |
82 | console.log(res) | |
83 | }).catch .... | |
84 | ||
85 | ``` | |
86 | ||
106744f7 | 87 | <strong> See examples folder for more details ( in particular if you want to use a pool for [multiple functions](./examples/multiFunctionExample.js) ).</strong> |
1a4ec243 | 88 | |
34a572eb | 89 | <h2 id="nv">Node versions</h2> |
90 | ||
d9992bf9 | 91 | You can use node versions 12.x , 13.x <br> |
1a4ec243 | 92 | |
34a572eb | 93 | <h2 id="api">API</h2> |
94 | ||
95 | ### `pool = new FixedThreadPool(numThreads, filePath, opts)` | |
96 | `numThreads` (mandatory) Num of threads for this worker pool <br> | |
97 | `filePath` (mandatory) Path to a file with a worker implementation <br> | |
98 | `opts` (optional) An object with these properties : | |
99 | - `errorHandler` - A function that will listen for error event on each worker thread | |
100 | - `onlineHandler` - A function that will listen for online event on each worker thread | |
101 | - `exitHandler` - A function that will listen for exit event on each worker thread | |
102 | - `maxTasks` - This is just to avoid not useful warnings message, is used to set <a href="https://nodejs.org/dist/latest-v12.x/docs/api/events.html#events_emitter_setmaxlisteners_n">maxListeners</a> on event emitters ( workers are event emitters) | |
103 | ||
104 | ### `pool = new DynamicThreadPool(min, max, filePath, opts)` | |
105 | `min` (mandatory) Same as FixedThreadPool numThreads , this number of threads will be always active <br> | |
106 | `max` (mandatory) Max number of workers that this pool can contain, the new created threads will die after a threshold ( default is 1 minute , you can override it in your worker implementation). <br> | |
107 | `filePath` (mandatory) Same as FixedThreadPool <br> | |
108 | `opts` (optional) Same as FixedThreadPool <br> | |
109 | ||
110 | ### `pool.execute(data)` | |
111 | Execute method is available on both pool implementations ( return type : Promise): <br> | |
112 | `data` (mandatory) An object that you want to pass to your worker implementation <br> | |
113 | ||
114 | ### `pool.destroy()` | |
115 | Destroy method is available on both pool implementations.<br> | |
116 | This method will call the terminate method on each worker. | |
117 | ||
118 | ||
119 | ### `class YourWorker extends ThreadWorker` | |
120 | `fn` (mandatory) The function that you want to execute on the worker thread <br> | |
121 | `opts` (optional) An object with these properties : | |
122 | - `maxInactiveTime` - Max time to wait tasks to work on ( in ms) , after this period the new worker threads will die. | |
123 | ||
48211d04 | 124 | <h2 id="cyp">Choose your pool</h2> |
106744f7 | 125 | Performance is one of the main target of these thread pool implementations, we want to have a strong focus on this.<br> |
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126 | We already have a bench folder where you can find some comparisons. |
127 | To choose your pool consider that with a FixedThreadPool or a DynamicThreadPool ( in this case is important the min parameter passed to the constructor) your application memory footprint will increase . <br> | |
106744f7 | 128 | Increasing the memory footprint, your application will be ready to accept more CPU bound tasks, but during idle time your application will consume more memory. <br> |
48211d04 | 129 | One good choose from my point of view is to profile your application using Fixed/Dynamic thread pool , and to see your application metrics when you increase/decrease the num of threads. <br> |
106744f7 | 130 | For example you could keep the memory footprint low choosing a DynamicThreadPool with 5 threads, and allow to create new threads until 50/100 when needed, this is the advantage to use the DynamicThreadPool. <br> |
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131 | But in general , <strong>always profile your application </strong> |
132 | ||
34a572eb | 133 | <h2 id="contribute">Contribute</h2> |
134 | ||
2650b26b | 135 | See guidelines [CONTRIBUTING](CONTRIBUTING.md) |
1a4ec243 | 136 | |
1a4ec243 | 137 | |
34a572eb | 138 | <h2 id="license">License</h2> |
1a4ec243 | 139 | |
9507c1d4 | 140 | [MIT](./LICENSE) |