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987e0026 | 1 | # Node Thread Pool :arrow_double_up: :on: |
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106744f7 | 7 | [![NODEP](https://img.shields.io/static/v1?label=dependencies&message=no%20dependencies&color=brightgreen |
8 | )](https://img.shields.io/static/v1?label=dependencies&message=no%20dependencies&color=brightgreen | |
9 | ) | |
b4b2dc8b | 10 | |
34a572eb | 11 | <h2>Contents </h2> |
12 | <h3 align="center"> | |
13 | <a href="#installation">Installation</a> | |
14 | <span> · </span> | |
15 | <a href="#usage">Usage</a> | |
16 | <span> · </span> | |
17 | <a href="#api">API</a> | |
18 | <span> · </span> | |
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19 | <a href="#cyp">Choose a pool</a> |
20 | <span> · </span> | |
34a572eb | 21 | <a href="#contribute">Contribute</a> |
22 | <span> · </span> | |
23 | <a href="#nv">Compatibility</a> | |
24 | <span> · </span> | |
25 | <a href="#license">License</a> | |
26 | </h3> | |
27 | ||
f349ea72 | 28 | <h2> Overview </h2> |
1a4ec243 | 29 | 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 | 30 | 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 | 31 | 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 | 32 | You have to implement your worker extending the ThreadWorker class<br> |
33 | <h2 id="installation">Installation</h2> | |
13031992 | 34 | |
1a4ec243 | 35 | ``` |
fd28144f | 36 | npm install @pioardi/node-thread-pool --save |
1a4ec243 | 37 | ``` |
34a572eb | 38 | <h2 id="usage">Usage</h2> |
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39 | |
40 | You can implement a worker in a simple way , extending the class ThreadWorker : | |
41 | ||
42 | ```js | |
43 | 'use strict' | |
fd28144f | 44 | const { ThreadWorker } = require('@pioardi/node-thread-pool') |
1a4ec243 | 45 | |
106744f7 | 46 | function yourFunction (data) { |
47 | // this will be executed in the worker thread, | |
48 | // the data will be received by using the execute method | |
49 | return { ok: 1 } | |
50 | } | |
51 | ||
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52 | class MyWorker extends ThreadWorker { |
53 | constructor () { | |
106744f7 | 54 | super(yourFunction, { maxInactiveTime: 1000 * 60}) |
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55 | } |
56 | } | |
57 | module.exports = new MyWorker() | |
58 | ``` | |
59 | ||
60 | Instantiate your pool based on your needed : | |
61 | ||
62 | ```js | |
63 | 'use strict' | |
fd28144f | 64 | const { FixedThreadPool, DynamicThreadPool } = require('@pioardi/node-thread-pool') |
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65 | |
66 | // a fixed thread pool | |
67 | const pool = new FixedThreadPool(15, | |
106744f7 | 68 | './yourWorker.js', |
69 | { errorHandler: (e) => console.error(e), onlineHandler: () => console.log('worker is online') }) | |
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70 | |
71 | // or a dynamic thread pool | |
72 | const pool = new DynamicThreadPool(10, 100, | |
106744f7 | 73 | './yourWorker.js', |
74 | { errorHandler: (e) => console.error(e), onlineHandler: () => console.log('worker is online') }) | |
75 | ||
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76 | pool.emitter.on('FullPool', () => console.log('Pool is full')) |
77 | ||
78 | // the execute method signature is the same for both implementations, | |
79 | // so you can easy switch from one to another | |
80 | pool.execute({}).then(res => { | |
81 | console.log(res) | |
82 | }).catch .... | |
83 | ||
84 | ``` | |
85 | ||
106744f7 | 86 | <strong> See examples folder for more details ( in particular if you want to use a pool for [multiple functions](./examples/multiFunctionExample.js) ).</strong> |
1a4ec243 | 87 | |
34a572eb | 88 | <h2 id="nv">Node versions</h2> |
89 | ||
d9992bf9 | 90 | You can use node versions 12.x , 13.x <br> |
1a4ec243 | 91 | |
34a572eb | 92 | <h2 id="api">API</h2> |
93 | ||
94 | ### `pool = new FixedThreadPool(numThreads, filePath, opts)` | |
95 | `numThreads` (mandatory) Num of threads for this worker pool <br> | |
96 | `filePath` (mandatory) Path to a file with a worker implementation <br> | |
97 | `opts` (optional) An object with these properties : | |
98 | - `errorHandler` - A function that will listen for error event on each worker thread | |
99 | - `onlineHandler` - A function that will listen for online event on each worker thread | |
100 | - `exitHandler` - A function that will listen for exit event on each worker thread | |
101 | - `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) | |
102 | ||
103 | ### `pool = new DynamicThreadPool(min, max, filePath, opts)` | |
104 | `min` (mandatory) Same as FixedThreadPool numThreads , this number of threads will be always active <br> | |
105 | `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> | |
106 | `filePath` (mandatory) Same as FixedThreadPool <br> | |
107 | `opts` (optional) Same as FixedThreadPool <br> | |
108 | ||
109 | ### `pool.execute(data)` | |
110 | Execute method is available on both pool implementations ( return type : Promise): <br> | |
111 | `data` (mandatory) An object that you want to pass to your worker implementation <br> | |
112 | ||
113 | ### `pool.destroy()` | |
114 | Destroy method is available on both pool implementations.<br> | |
115 | This method will call the terminate method on each worker. | |
116 | ||
117 | ||
118 | ### `class YourWorker extends ThreadWorker` | |
119 | `fn` (mandatory) The function that you want to execute on the worker thread <br> | |
120 | `opts` (optional) An object with these properties : | |
121 | - `maxInactiveTime` - Max time to wait tasks to work on ( in ms) , after this period the new worker threads will die. | |
122 | ||
48211d04 | 123 | <h2 id="cyp">Choose your pool</h2> |
106744f7 | 124 | 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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125 | We already have a bench folder where you can find some comparisons. |
126 | 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 | 127 | 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 | 128 | 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 | 129 | 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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130 | But in general , <strong>always profile your application </strong> |
131 | ||
34a572eb | 132 | <h2 id="contribute">Contribute</h2> |
133 | ||
134 | See guidelines [CONTRIBUTING](./.github/CONTRIBUTING.md) | |
1a4ec243 | 135 | |
1a4ec243 | 136 | |
34a572eb | 137 | <h2 id="license">License</h2> |
1a4ec243 | 138 | |
9507c1d4 | 139 | [MIT](./LICENSE) |
26a71e7b | 140 |