If the threads and their scheduling are implemented wholly by the language, not the OS, then perhaps the ordering of their wake-ups could be guaranteed -- although I'm not sure these languages do guarantee it.

Maybe they had some reason for using a LIFO instead of a FIFO, who knows; one needs to check these things.

However, the thing that triggered me to comment was this part:

> If it runs significantly after 953ms, that’s OK, but there probably needed to be a good reason, like the entire thread being blocked unexpectedly.

This is simply mistaken, in strongly implying that it takes unusual conditions for events to lag significantly; actually that is just normal functioning, and does not need "unexpected blocking" or anything else unusual or rare to occur.

It is ameliorated a lot by avoiding heavy loading of systems (that doesn't fix it, but it can reduce strange behavior down to a statistically tolerable level).