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    cluster-map

    1.0.2 • Public • Published

    cluster-map

    Travis build status NPM version Canonical Code Style

    Abstracts execution of tasks in parallel using Node.js cluster.

    It is a high level abstraction around a common pattern used to delegate a list of tasks to the workers.

    API

    import {
        createClusterMap
    } from 'cluster-map';
     
    /**
     * Executes tasks in parallel using Node.js cluster.
     * @typedef {Function} createClusterMap~createMap
     * @param {string[]} tasks An array of unique tasks sent to the workers.
     * @returns {Promise} 
     */
     
    /**
     * @typedef {Object} createClusterMap~configuration
     * @property {number} numberOfProcesses Defines number of processes that will be forked (default: number of OS CPUs as determined using https://nodejs.org/api/os.html#os_os_cpus).
     * @property {boolean} log Used to enable logging (https://github.com/gajus/cluster-map#logging) (default: false).
     * @property {number} timeout Used to enable logging of the tasks that take longer than the specified time (in milliseconds) (default: 5000).
     */
     
    /**
     * Used to create a pre-configured instance of `clusterMap`.
     * @param {createClusterMap~cluster} cluster https://nodejs.org/api/cluster.html
     * @param {createClusterMap~configuration} configuration 
     * @returns {createMap} 
     */
    createClusterMap(cluster);

    handleTask function is used to receive tasks and respond to the master.

    import {
        handleTask
    } from 'cluster-map';
     
     
    /**
     * Handles a task and returns a promise that is resolved with the result of the task.
     * @typedef {Function} handleTask~handler
     * @param {string} task 
     * @returns {Promise} 
     */
     
    /**
     * @param {handleTask~handler} task 
     */
    handleTask(cluster);

    Communication With Worker

    import {
        handleTask
    } from 'cluster-map';
     
    handleTask((task, callback) => {
     
    });

    Example

    In this example,

    • Master declares an array of tasks (['task 1', 'task 2', 'task 3']).
    • createClusterMap is used to create an instance of clusterMap.
    • clusterMap is used to task the workers.
    • Workers handle the tasks and reply to the master.
    • clusterMap waits for all tasks to be processed.
    • When all tasks are processes, clusterMap resolves with an array of results.
    import cluster from 'cluster';
    import {
        createClusterMap,
        handleTask
    } from 'cluster-map';
     
    if (cluster.isMaster) {
        let clusterMap,
            tasks;
     
        tasks = [
            'task 1',
            'task 2',
            'task 3'
        ];
     
        clusterMap = createClusterMap(cluster);
     
        clusterMap(tasks)
            .then((results) => {
                console.log(results);
            });
    }
     
    if (cluster.isWorker) {
        handleTask((task) => {
            return Promise.resolve(task.slice(-1));
        });
    }

    Using a separate file

    master.js

    import cluster from 'cluster';
    import {
        createClusterMap
    } from 'cluster-map';
     
    let clusterMap,
        tasks;
     
    tasks = [
        'task 1',
        'task 2',
        'task 3'
    ];
     
    cluster.setupMaster({
        exec: path.resolve(__dirname, 'worker.js')
    });
     
    clusterMap = createClusterMap(cluster);
     
    clusterMap(tasks)
        .then((results) => {
     
        });

    worker.js

    import {
        handleTask
    } from 'cluster-map';
     
    handleTask((task) => {
        return Promise.resolve(task.slice(-1));
    });

    Logging

    Logging is enabled using log configuration.

    Logging produces an output that describes:

    • Number of forked processes.
    • Logs time when worker is assigned a task.
    • Logs time when worker responds with a result.
    • Logs time when either of the tasks take longer than the timeout configuration to execute.
    [03:36:46] Spawning 8 worker process(es).
    [03:36:46] Tasking worker #1. "/bin/babel-external-helpers.js"
    [03:36:46] Tasking worker #3. "/bin/babel-node.js"
    [03:36:46] Tasking worker #5. "/bin/babel-plugin.js"
    [03:36:46] Tasking worker #4. "/bin/babel.js"
    [03:36:46] Tasking worker #7. "/index.js"
    [03:36:46] Tasking worker #6. "/lib/_babel-node.js"
    [03:36:46] Tasking worker #2. "/lib/babel-external-helpers.js"
    [03:36:46] Tasking worker #8. "/lib/babel-node.js"
    [03:36:48]
    Received result from:      /bin/babel-node.js
    Tasks in progress (count): 7
    Tasks in progress:
      - /bin/babel-external-helpers.js
      - /bin/babel-plugin.js
      - /bin/babel.js
      - /index.js
      - /lib/_babel-node.js
      - /lib/babel-external-helpers.js
      - /lib/babel-node.js
    Remaining tasks (count):   495
    [03:36:48] Tasking worker #3. /lib/babel-plugin/index.js
    [03:36:48]
    Received result from:      /bin/babel-external-helpers.js
    Tasks in progress (count): 7
    Tasks in progress:
      - /bin/babel-plugin.js
      - /bin/babel.js
      - /index.js
      - /lib/_babel-node.js
      - /lib/babel-external-helpers.js
      - /lib/babel-node.js
      - /lib/babel-plugin/index.js
    Remaining tasks (count):   494
    

    Install

    npm i cluster-map

    DownloadsWeekly Downloads

    1,152

    Version

    1.0.2

    License

    BSD-3-Clause

    Last publish

    Collaborators

    • gajus