<div align="center">
-<img src="./docs/logo.png" width="340px" height="266px"/>
+<img src="./images/logo.png" width="340px" height="266px"/>
</div>
-<h2 align="center">Node Thread Pool :arrow_double_up: :on:</h2>
+<h2 align="center">Node Thread Pool and Cluster Pool :arrow_double_up: :on:</h2>
+<h2 align="center">
+ <a href="https://ko-fi.com/Q5Q31D6QY">
+ <img alt="Ko-fi" src="https://ko-fi.com/img/githubbutton_sm.svg"></a>
+</h2>
<p align="center">
<a href="https://www.npmjs.com/package/poolifier">
<img alt="No dependencies" src="https://img.shields.io/static/v1?label=dependencies&message=no%20dependencies&color=brightgreen"></a>
</p>
-## Why Poolifier?
+## Why Poolifier?
-Poolifier is used to perform heavy CPU bound 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).
+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.
With poolifier you can improve your **performance** and resolve problems related to the event loop.
-Moreover you can execute your CPU tasks using an API designed to improve the **developer experience**.
+Moreover you can execute your tasks using an API designed to improve the **developer experience**.
+Please consult our <a href="#general-guidance">general guidelines</a>
-- Performance :racehorse:
+- Performance :racehorse: [benchmarks](./benchmarks/README.md)
- Security :bank: :cop: [](https://sonarcloud.io/dashboard?id=pioardi_poolifier) [](https://sonarcloud.io/dashboard?id=pioardi_poolifier)
- Easy to use :couple:
- Easy switch from a pool to another, easy to tune :heavy_check_mark:
<span> · </span>
<a href="#api">API</a>
<span> · </span>
- <a href="#choose-your-pool">Choose your pool</a>
+ <a href="#general-guidance">General guidance</a>
<span> · </span>
<a href="#contribute">Contribute</a>
<span> · </span>
'use strict'
const { ThreadWorker } = require('poolifier')
-function yourFunction(data) {
+function yourFunction (data) {
// this will be executed in the worker thread,
// the data will be received by using the execute method
return { ok: 1 }
'./yourWorker.js',
{ errorHandler: (e) => console.error(e), onlineHandler: () => console.log('worker is online') })
-pool.emitter.on('FullPool', () => console.log('Pool is full'))
+pool.emitter.on('busy', () => console.log('Pool is busy'))
// the execute method signature is the same for both implementations,
// so you can easy switch from one to another
**See examples folder for more details (in particular if you want to use a pool for [multiple functions](./examples/multiFunctionExample.js)).**
**Now TypeScript is also supported, find how to use it into the example folder**.
+Remember that workers can only send and receive serializable data.
+
## Node versions
You can use node versions 12.x, 13.x, 14.x
- `errorHandler` - A function that will listen for error event on each worker
- `onlineHandler` - A function that will listen for online event on each worker
- `exitHandler` - A function that will listen for exit event on each worker
-- `maxTasks` - This is just to avoid not useful warnings message, is used to set [maxListeners](https://nodejs.org/dist/latest-v12.x/docs/api/events.html#events_emitter_setmaxlisteners_n) on event emitters (workers are event emitters)
### `pool = new DynamicThreadPool/DynamicClusterPool(min, max, filePath, opts)`
This option only apply to the newly created workers.
Default: `SOFT`
-## Choose your pool
+## General guidance
Performance is one of the main target of these worker pool implementations, we want to have a strong focus on this.
We already have a bench folder where you can find some comparisons.
+
+### Internal Node.js thread pool
+
+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.
+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).
+
+Now **if your task runs on libuv thread pool**, you can try to:
+
+- Tune the libuv thread pool size setting the [UV_THREADPOOL_SIZE](https://nodejs.org/api/cli.html#cli_uv_threadpool_size_size)
+
+and/or
+
+- 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.**
+
+### Cluster vs Threads worker pools
+
+**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.
+Thread pools are built on top of Node.js [worker-threads](https://nodejs.org/api/worker_threads.html#worker_threads_worker_threads) module.
+
+**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.
+Consider that by default Node.js already has great performance for I/O tasks (asynchronous I/O).
+Cluster pools are built on top of Node.js [cluster](https://nodejs.org/api/cluster.html) module.
+
+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).
+But in general, **always profile your application**
+
+### Fixed vs Dynamic pools
+
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.
-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.
+Increasing the memory footprint, your application will be ready to accept more tasks, but during idle time your application will consume more memory.
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.
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.
But in general, **always profile your application**
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