Limit to number of Fibers Aff can schedule?

chexxor · May 30, 2018, 2:57am

hyperisco [4:12 PM]
there is a limit on how many fibers Aff can schedule… how would I be notified if that limit was hit

natefaubion [4:12 PM]
No
It is possible to hit a limit if you fork, and in that fork you immediately fork, and in that fork you immediately fork, etc, until such a point that it will blow the stack.
Because the runtime right now immediately starts evaluating forks, until it hits an async barrier (edited)
oh, and OOM I guess ¯_(ツ)_/¯

hyperisco [4:17 PM]
well I don’t think I’ve done that because the javascript console does not hang
is this just for scare factor then?

github.com

slamdata/purescript-aff/blob/v4.1.1/src/Control/Monad/Aff.js#L106


function runAsync(left, eff, k) {
  try {
    return eff(k)();
  } catch (error) {
    k(left(error))();
    return nonCanceler;
  }
}


var Scheduler = function () {
  var limit    = 1024;
  var size     = 0;
  var ix       = 0;
  var queue    = new Array(limit);
  var draining = false;


  function drain() {
    var thunk;
    draining = true;
    while (size !== 0) {
      size--;

looks like a ring buffer
and failure also seems to be silent

natefaubion [4:19 PM]
If a limit is hit, will start greedily evaluating the callbacks until there’s enough room, I believe

In practice this limit is extremely difficult to hit

natefaubion [4:21 PM]
you would have to have a lot of async actions that resolve synchronously

natefaubion [4:21 PM]
The scheduler is only used to resolve async actions
If something just stops working and exits, sounds like a dead lock