Eats all memory very quickly then killed by OOM about node-bignum

[rvagg]

Unfortunately I don't have a good answer for you here ; it could be a GC problem with the large loop, perhaps if it was broken up across event loop turns you might have different results, unfortunately that's not a great answer because it would significantly complicate your code.

I'll leave this issue open in the hope that someone else can answer it--I'm more of a maintainer rather than an expert user unfortunately!

[ZiCog]

I tried your suggestion and iterated the loop via a setInterval(), also tried a 1ms setTimeout().

This reduces my CPU load down a few percent and I guess it would take a little over an hour to complete.

Sadly it still ramps up to 30% of my 3GB RAM here after a few minutes.

Here is the code:
var bigNumber = require("bignum");

function fibo_iterative(n, callback) {
    var first = bigNumber(0),
        second = bigNumber(1),
        next = bigNumber(0),
        loop,
        c;
    if (n <= 1) {
         callback (bigNumber(n));
    } else {
        c = 0;
        (function loop () {
            if (c < n - 1) {
                next = first.add(second);
                first = second;
                second = next;
                c += 1;
                //setImmediate(loop);
                setTimeout(loop, 1);
            } else {
                callback (next);
            }
        }());
    }
}
var n = 4784969;  // The first fibo number with one million digits!
fibo_iterative(n, function (r) {
    var rs = r.toString();
    console.log("The " + rs.length + " digits of fibo(" + n + ") are:");
    console.log(rs);
    console.log("Done.");
});