A node.js library to run cpu-intensive tasks in a separate processes and not block the event loop.
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worker-nodes

A node.js library to run cpu-intensive tasks in a separate processes and to not block the event loop.

Installation

$ npm install worker-nodes

Node.js greater than 6.6.0 highly recommended.

API Reference

WorkerNodes

Kind: global class

new WorkerNodes(path, [options])

Param Type Description
path String An absolute path to the module that will be run in the workers.
[options] Object See WorkerNodesOptions for a detailed description.

workerNodes.call : Proxy

This exposes the api of a module that the worker nodes are working on. If the module is a function, you can call this directly. If the module exports multiple functions, you can call them as they were properties of this proxy.

Kind: instance property of WorkerNodes

workerNodes.ready() ⇒ Promise

A method to check if the minimum required number of workers are ready to serve the calls.

Kind: instance method of WorkerNodes
Returns: Promise - resolves with a WorkerNodes instance

workerNodes.terminate() ⇒ Promise

Starts the process of terminating this instance.

Kind: instance method of WorkerNodes
Returns: Promise - - resolved when the instance is terminated.

WorkerNodesOptions

Describes a WorkerNodes options.

Kind: global class

options.autoStart : Boolean

Whether should initialize the workers before a first call.

If true, depending on the lazyStart option, it will start the min or max number of workers.

Kind: instance property of WorkerNodesOptions
Default: false

options.lazyStart : Boolean

Whether should start a new worker only if all the others are busy.

Kind: instance property of WorkerNodesOptions
Default: false

options.minWorkers : Number

The minimum number of workers that needs to be running to consider the whole pool as operational.

Kind: instance property of WorkerNodesOptions
Default: 0

options.maxWorkers : Number

The maximum number of workers that can be running at the same time. Defaults to the number of cores the operating system sees.

Kind: instance property of WorkerNodesOptions

options.maxTasks : Number

The maximum number of calls that can be handled at the same time. Exceeding this limit causes MaxConcurrentCallsError to be thrown.

Kind: instance property of WorkerNodesOptions
Default: Infinity

options.maxTasksPerWorker : Number

The number of calls that can be given to a single worker at the same time.

Kind: instance property of WorkerNodesOptions
Default: 1

options.taskTimeout : Number

The number milliseconds after which a call is considered to be lost. Exceeding this limit causes TimeoutError to be thrown and a worker that performed that task to be killed.

Kind: instance property of WorkerNodesOptions
Default: Infinity

options.taskMaxRetries : Number

The maximum number of retries that will be performed over a task before reporting it as incorrectly terminated. Exceeding this limit causes ProcessTerminatedError to be thrown.

Kind: instance property of WorkerNodesOptions
Default: 0

options.workerEndurance : Number

The maximum number of calls that a single worker can handle during its whole lifespan. Exceeding this limit causes the termination of the worker.

Kind: instance property of WorkerNodesOptions
Default: Infinity

options.workerStopTimeout : Number

The timeout value (in milliseconds) for the worker to stop before sending SIGKILL.

Kind: instance property of WorkerNodesOptions
Default: 100

Example

Given /home/joe.doe/workspace/my-module.js:

module.exports = function myTask() {
    return 'hello from separate process!';
};

you can run it through the worker nodes as follows:

const WorkerNodes = require('worker-nodes');
const myModuleWorkerNodes = new WorkerNodes('/home/joe.doe/workspace/my-module');

myModuleWorkerNodes.call().then(msg => console.log(msg));  // -> 'hello from separate process!'

For more advanced examples please refer to the test cases.

Running tests

Check out the library code and then:

$ npm install
$ npm test

Benchmarks

To run tests, type:

$ npm install
$ npm run benchmark

It will run a performance test against the selected libraries:

  • data in: an object that consists of a single field that is a 0.5MB random string
  • data out: received object stringified and concatenated with another 1MB string

Example results:

results for 100 executions

name                time: total [ms]  time usr [ms]  time sys [ms]  worker usr [ms]  worker sys [ms]  mem rss [MB]  worker rss [MB]  errors
------------------  ----------------  -------------  -------------  ---------------  ---------------  ------------  ---------------  ------
no-workers                       150            239             42                0                0            98                0       0
worker-nodes@1.2.0              1521            646            528              641              367           272              119       0
workerpool@2.1.0               12055           7356           5726              896              212           731               74       0
worker-farm@1.3.1              12124           6711           5501             1577              446           689               74       0
process-pool@0.3.4             12348           6866           5474             1696              458           698               76       0
worker-pool@3.0.2              14029           7633           5604             2285              649           769              104       0

os : Darwin / 15.5.0 / x64
cpu : Intel(R) Core(TM) i7-4578U CPU @ 3.00GHz × 4
node : 6.9.1 / v8: 5.1.281.84

See also

sources of inspiration:

License

Copyright 2016 Grupa Allegro Sp. z o.o.

Licensed under the Apache License, Version 2.0 (the "License"); you may not use this file except in compliance with the License. You may obtain a copy of the License at

http://www.apache.org/licenses/LICENSE-2.0

Unless required by applicable law or agreed to in writing, software distributed under the License is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the License for the specific language governing permissions and limitations under the License.