Concurrent rAF loops are not deterministic

[paulrouget]

<script>
  var i = 0;

  var loopA = t => {
    console.log("A: " + t);

    if (i++ < 5) {
      requestAnimationFrame(loopA);
    }
  };

  var loopB = t => {
    console.log("B: " + t);    
    if (i < 5) {
      requestAnimationFrame(loopB);
    }
  };

  loopA();
  loopB();
</script>

Chrome and Firefox:

====
A
B
A
B
A
B
A
B
A
B
A

Servo:

====
A
B
B
A
B
A
A
B
A
B
A

[nox]

We use a HashMap, that doesn't preserve order. I'm switching it to a BTreeMap.

[nox]

@paulrouget Do you think we have intermittent failures due to this?

[paulrouget]

Do you think we have intermittent failures due to this?

I don't know, but it was causing some weird issues in browserhtml.