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node-narrow is a library which shrinks a given callback parallel execution in a limited number of threads, receiving the bunch of data (array of tasks).

Inspired from node-async#queue.


Push a big bunch of data and handle it in maximum 5 simultaneous threads:

var Narrow = require('narrow');

var narrow = new Narrow(5, function(str, callback){
        callback(null, str.toUpperCase());
    }, 1000)

var tasks = [];
for (var i = 0; i < 10; i++) {
    tasks.push('something' + i);

var start = new Date;

narrow.on('complete', function(result){
    console.log('%s after %dms', result, new Date - start);

narrow.pushAll(tasks, function(){

Will output:

SOMETHING0 after 1002ms
SOMETHING1 after 1012ms
SOMETHING2 after 1012ms
SOMETHING3 after 1012ms
SOMETHING4 after 1012ms
SOMETHING5 after 2012ms
SOMETHING6 after 2012ms
SOMETHING7 after 2013ms
SOMETHING8 after 2016ms
SOMETHING9 after 2016ms

Timeouts support

todo: document

See more examples in examples directory.


npm install narrow