Simple worker threads pool using Node's worker_threads module. Compatible with ES6+ Promise, Async/Await.
npm install node-worker-threads-pool
Simple worker threads pool using Node's worker_threads module. Compatible with ES6+ Promise, Async/Await and TypeScript🚀.
- Use StaticPool to create a threads pool with a task from worker file or from task function provided to make use of multi-core processor.
- Use DynamicPool to create a threads pool with different tasks provided each call. Thus you can get more flexibility than StaticPool and make use of multi-core processor.
- Gain extra controllability for the underlying threads by the power of worker_threads, like resourceLimits, SHARE_ENV, transferList and more.
1. This module can only run in Node.js.
``
npm install node-worker-threads-pool --save
Quickly create a pool with static task:
`js
const { StaticPool } = require('node-worker-threads-pool');
const staticPool = new StaticPool({
size: 4,
task: (n) => n + 1
});
staticPool.exec(1).then((result) => {
console.log('result from thread pool:', result); // result will be 2.
});
`
There you go! 🎉
Create a pool with dynamic task:
`js
const { DynamicPool } = require('node-worker-threads-pool');
const dynamicPool = new DynamicPool(4);
dynamicPool
.exec({
task: (n) => n + 1,
param: 1
})
.then((result) => {
console.log(result); // result will be 2.
});
dynamicPool
.exec({
task: (n) => n + 2,
param: 1
})
.then((result) => {
console.log(result); // result will be 3.
});
`
About the differences between StaticPool and DynamicPool, please see this issue.
Instance of StaticPool is a threads pool with static task provided.
- opt
`js
// Access the workerData by requiring it.
const { parentPort, workerData } = require('worker_threads');
// Something you shouldn"t run in main thread
// since it will block.
function fib(n) {
if (n < 2) {
return n;
}
return fib(n - 1) + fib(n - 2);
}
// Main thread will pass the data you need
// through this event listener.
parentPort.on('message', (param) => {
if (typeof param !== 'number') {
throw new Error('param must be a number.');
}
const result = fib(param);
// Access the workerData.
console.log('workerData is', workerData);
// return the result to main thread.
parentPort.postMessage(result);
});
`
`js
const { StaticPool } = require('node-worker-threads-pool');
const filePath = 'absolute/path/to/your/worker/script';
const pool = new StaticPool({
size: 4,
task: filePath,
workerData: 'workerData!'
});
for (let i = 0; i < 20; i++) {
(async () => {
const num = 40 + Math.trunc(10 * Math.random());
// This will choose one idle worker in the pool
// to execute your heavy task without blocking
// the main thread!
const res = await pool.exec(num);
console.log(Fibonacci(${num}) result:, res);`
})();
}
You can access workerData in task function using this keyword:
`js`
const pool = new StaticPool({
size: 4,
workerData: 'workerData!',
task() {
console.log(this.workerData);
}
});
⚠️Remember not to use arrow function as a task function when you use this.workerData, because arrow function don't have this binding.
- param The param your worker script or task function need.
- Returns:
The simplest way to execute a task without considering other configurations. This will choose an idle worker in the pool to execute your heavy task with the param you provided. The Promise is resolved with the result.
- Returns:
Create a task executor of this pool. This is used to apply some advanced settings to a task. See more details of StaticTaskExecutor.
Call worker.terminate() for every worker in the pool and release them.
Executor for StaticPool. Used to apply some advanced settings to a task.
`js
const staticPool = new StaticPool({
size: 4,
task: (buf) => {
// do something with buf.
}
});
const buf = Buffer.alloc(1024 * 1024);
staticPool
.createExecutor() // create a StaticTaskExecutor instance.
.setTimeout(1000) // set timeout for task.
.setTransferList([buf.buffer]) // set transferList.
.exec(buf) // execute!
.then(() => console.log('done!'));
`
- t timeout in millisecond.
- Returns:
Set timeout for this task.
- transferList
- Returns:
Set [transferList] for this task. This is useful when you want to pass some huge data into worker thread.
- param
- Returns:
Execute this task with the parameter and settings provided. The Promise is resolved with the result your task returned.
Instance of DynamicPool is a threads pool executes different task functions provided every call.
- size Number of workers in this pool.opt
-
- Set true to enable [SHARE_ENV] for every threads in pool.resourceLimits
-
- opt
- Function as a task to do. ⚠️Notice: You can NOT access variables defined outside the task function!timeout
- Timeout in milisecond for limiting the execution time. When timeout, the function will throw a TimeoutError, use isTimeoutError function to detect it.
- Returns:
Choose one idle worker in the pool to execute your task function. The Promise is resolved with the result your task returned.
- task Function task function.
- Returns:
Create a task executor of this pool. This is used to apply some advanced settings to a task. See more details of DynamicTaskExecutor.
Call worker.terminate() for every worker in the pool and release them.
Executor for DynamicPool. Used to apply some advanced settings to a task.
`js
const dynamicPool = new DynamicPool(4);
const buf = Buffer.alloc(1024 * 1024);
dynamicPool
.createExecutor((buf) => {
// do something with buf.
})
.setTimeout(1000) // set timeout for task.
.setTransferList([buf.buffer]) // set transferList.
.exec(buf) // execute!
.then(() => console.log('done!'));
`
- t timeout in millisecond.
- Returns:
Set timeout for this task.
- transferList
- Returns:
Set [transferList] for this task. This is useful when you want to pass some huge data into worker thread.
- param
- Returns:
Execute this task with the parameter and settings provided. The Promise is resolved with the result your task returned.
Detect if a thrown error is TimeoutError.
- err The error you want to detect.
- Returns true if the error is a TimeoutError.
`js
const { isTimeoutError } = require("node-worker-threads-pool");
// create pool.
...
// static pool exec with timeout.
const timeout = 1000;
try {
const res = await staticPool.exec(param, timeout);
} catch (err) {
if (isTimeoutError(err)) {
// deal with timeout.
} else {
// deal with other errors.
}
}
// dynamic pool exec with timeout.
const timeout = 1000;
try {
const res = await dynamicPool.exec({
task() {
// your task.
},
timeout
});
} catch (err) {
if (isTimeoutError(err)) {
// deal with timeout.
} else {
// deal with other errors.
}
}
`
If you are using webpack in your project and want to import third-party libraries in task function, please use this.require:
`js`
const staticPool = new StaticPool({
size: 4,
task() {
const lib = this.require('lib');
// ...
}
});
`js
const dynamicPool = new DynamicPool(4);
dynamicPool
.exec({
task() {
const lib = this.require('lib');
// ...
}
})
.then((result) => {
// ...
});
``
[cloneable data]: https://developer.mozilla.org/en-US/docs/Web/API/Web_Workers_API/Structured_clone_algorithm
[resourcelimits]: https://nodejs.org/api/worker_threads.html#worker_threads_worker_resourcelimits
[share_env]: https://nodejs.org/dist/latest-v14.x/docs/api/worker_threads.html#worker_threads_worker_share_env
[transferlist]: https://nodejs.org/dist/latest-v14.x/docs/api/worker_threads.html#worker_threads_port_postmessage_value_transferlist
[arrow function]: https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Functions/Arrow_functions