Thread JS - A simple library for JavaScript Thread support

Introduction

ThreadJS is JavaScript library to simplify executing your JavaScript code in different threads. Though this library uses 'Workers' internally, interaction model is changed from a message based mechanism to a simple promise based execution pattern. Since the 'Worker' specification is not fully supported by all the major browsers, Thread JS comes with a 'fallback' mechanism to support unsupported browsers which will continue executing your JavaScript code within the 'Main Thread' instead.

Workers

The 'Worker' interface spawns real OS-level threads. Since Thread JS uses workers internally, you are actually creating real OS-level threads to execute your JavaScript code. Web workers utilizes carefully controlled communication points with other threads limiting the ability to cause concurrency problems.

Note: There's no access to non-thread safe components or the DOM and you have to pass specific data in and out of a thread through serialized objects (Copied). Therefore its highly unlikely hard to cause problems in your code while executing in parallel.

Example 1:

Following code uses a new Thread to compute the summation of numbers from 1 - 1,000,000,000 and returns the results to main Thread.

var thread = new Thread();
thread.start(1000000000, function (size) {
    var x = 0;
    for (var i = 1; i <= size; i++) {
        x = x + i;
    }
    return x;
}).then(function (result) {
    console.log('Result: ' + result);
    this.close();
}).fail(function (error) {
    console.log('Error: ' + error);
    this.close();
});

See the results in: JSFiddle

Example 2:

Comparing Single-Thread vs Multi-Thread summation of numbers from 1 - 2,000,000,000. Note: Multi-Thread approach uses almost half of the time needed for Single-Thread approach.

/*Start: Code segment 1 : Note :- This code runs in the Main Thread*/
var s1_start = new Date();
var x = 0;
for (var i = 1; i <= 2000000000; i++) {
    x = x + i;
}
var s1_end = new Date();
console.log('Result 1: ' + x + ' ( ' + (s1_end - s1_start) + '  milliseconds)');

/*End: Code segment 1 */

/*Start: Code segment 2 : Note :- Two Threads are used to compute the value*/
var s2_start = new Date(),
    s2_end;
var y = 0;
var thread1 = new Thread();
thread1.start(null, function () {
    var x = 0;
    for (var i = 1; i <= 1000000000; i++) {
        x = x + i;
    }
    return x;
}).then(function (result) {
    y = y + result;
    s2_end = new Date();
    console.log('Result 2: ' + y + ' ( ' + (s2_end - s2_start) + '  milliseconds)');
    this.close();
});

var thread2 = new Thread();
thread2.start(null, function () {
    var x = 0;
    for (var i = 1000000001; i <= 2000000000; i++) {
        x = x + i;
    }
    return x;
}).then(function (result) {
    y = y + result;
    s2_end = new Date();
    console.log('Result 2: ' + y + ' ( ' + (s2_end - s2_start) + '  milliseconds)');
    this.close();
})

/*End: Code segment 2 */

See the results in: JSFiddle

Browser Support

Thread JS currently supports Google Chrome 4.0 + and Mozilla Firefox 3.5+ and Fallback to Single Thread Support for Other browsers.

Note: Though IE10/11 is in the compatibility list, Security Bug passing Blobs to Workers makes it fallback.

Questions?

If you have any questions, feel free to contact me Email: ashan256@gmail.com, Linkedin: Profile Link