[w-ll]

I dont know, but I would assume it has to deal with the fact you can't predict how long a job will take to complete, and a random selection would have more resources-more free-more often, verses FIFO where a group of really large tasks could halt everything.

[manmal]

And what if they turned the whole thing into a request queue and workers get the "messages" as they become available? To ensure there are no timeouts, they could define a max time a request may stay in the queue, and then take it out and handle it with emergency workers or kill it?

[kordless]

That's exactly correct. Given jobs cleared out quick, that wouldn't necessarily be the case.