stupid GC stressing code

gistfile1.js

// To make the benchmark results predictable, we replace Math.random
// with a 100% deterministic alternative.
Math.random = (function() {
  var seed = 49734321;
  return function() {
    // Robert Jenkins' 32 bit integer hash function.
    seed = ((seed + 0x7ed55d16) + (seed << 12))  & 0xffffffff;
    seed = ((seed ^ 0xc761c23c) ^ (seed >>> 19)) & 0xffffffff;
    seed = ((seed + 0x165667b1) + (seed << 5))   & 0xffffffff;
    seed = ((seed + 0xd3a2646c) ^ (seed << 9))   & 0xffffffff;
    seed = ((seed + 0xfd7046c5) + (seed << 3))   & 0xffffffff;
    seed = ((seed ^ 0xb55a4f09) ^ (seed >>> 16)) & 0xffffffff;
    return (seed & 0xfffffff) / 0x10000000;
  };
})();


function makeRandomKey() {
    var a = "a".charCodeAt(0);
    var z = "z".charCodeAt(0);

    var key = [];
    for (var i = 0; i < 20; i++) {
        key.push(a + Math.floor(Math.random() * (z - a + 1)));
    }

    return String.fromCharCode.apply(String, key) + Math.floor(Math.random() * 1000);
}

var totalkeys = 0;
var db = new DBSlice;

function DBSlice(next) {
    this.nkeys = 0;
    this.table = Object.create(null);
    this.next = next;
}

function Payload(depth) {
    if (depth < 3) {
        this.x = new Payload(depth + 1);
        this.y = makeRandomKey();
        this.z = new Payload(depth + 1);
        this.k = makeRandomKey();
        this.l = 10101;
    }
}

function Rand(n) { return Math.floor(Math.random() * n); }

DBSlice.prototype.insertNewKey = function () {
    do {
        var key = makeRandomKey();
    } while (key in this.table);
    this.nkeys++;
    totalkeys++;
    this.table[key] = new Payload();
    if (this.nkeys === 100000) {
      print("100000 keys created (total keys: " + totalkeys + ")");
      return new DBSlice(this);
    }
    return this;
}

function permutatedb() {
    while (true) {
        switch (Rand(5)) {
            case 0:
            case 1:
            case 2:
                new Payload();  // make some garbage
                break;
            case 3:
            case 4:
                for (var i = 0, n = Rand(5) + 5; i < n; i++) db = db.insertNewKey(); // grow database
                break;
        }
    }
}

permutatedb();