node.js weirdness

**superuser** · 10-13-2015, 12:54 PM

This is weird. At least with node.js v4, consider the following two programs:

Program #1 :

Code:

'use strict';

function f(x, y) {
    /*

     Lorem ipsum dolor sit amet, consectetuer adipiscing elit. Sed posuere interdum sem. Quisque ligula eros ullamcorper
     quis, lacinia quis facilisis sed sapien. Mauris varius diam vitae arcu. Sed arcu lectus auctor vitae, consectetuer et
     venenatis eget velit. Sed augue orci, lacinia eu tincidunt et eleifend nec lacus. Donec ultricies nisl ut felis,
     suspendisse potenti. Lorem ipsum ligula ut hendrerit mollis, ipsum erat vehicula risus, eu suscipit sem libero nec
     erat. Aliquam volutpat. Sed congue augue vitae neque. Nulla consectetuer pede. Fusce purus morbi tortor magna
     condimentum vel, placerat id blandit sit amet tortor.

     */

    return (x + y);
}

for (let i = 0; i < 1000000000; i++) {
    if (f(i, i++) < 5) {
        //
    }
}

Program #2 :

Code:

'use strict';

function f(x, y) {
    /*

     Lorem ipsum dolor sit amet, consectetuer adipiscing elit. Sed posuere interdum sem. Quisque ligula eros ullamcorper
     quis, lacinia quis facilisis sed sapien. Mauris varius diam vitae arcu. Sed arcu lectus auctor vitae, consectetuer et
     venenatis eget velit. Sed augue orci, lacinia eu tincidunt et eleifend nec lacus. Donec ultricies nisl ut felis,
     erat. Aliquam volutpat. Sed congue augue vitae neque. Nulla consectetuer pede. Fusce purus morbi tortor magna
     condimentum vel, placerat id blandit sit amet tortor.

     */

    return (x + y);
}

for (let i = 0; i < 1000000000; i++) {
    if (f(i, i++) < 5) {
        //
    }
}

Now when ran and timed, here's the results for program #1 :

Code:

real    0m4.795s
user    0m4.732s
sys     0m0.012s

and program #2 :

Code:

real    0m1.999s
user    0m1.969s
sys     0m0.016s

Can you spot the difference and why the second program is twice as fast as the first one?

**tls** · 10-13-2015, 06:47 PM

The comment actually affects runtime?

**superuser** · 10-13-2015, 07:27 PM

Yup! For some reason, if the contents of the function exceeds 600 characters (including comments!), the function is not inlined. Sounds like a bug to me..