method
Job.parallel_for
Job.parallel_for(count, work, ctx) -> void
Run work(i, ctx) for every i in [0, count) on real OS threads, and return when every call has
finished. The indices are split into chunks shared by a worker pool (one thread per core but one,
started on first use) and the calling thread, so each index runs exactly once, in no particular order.
work is a top-level function taking (i: int, ctx), named with fn; ctx is whatever it computes
on (words, bytes or a pointer). A worker computes on what it was handed and writes only its own
index's results: it must not spawn, despawn, push onto a list another thread can see, or use
Http or Audio. spawn and despawn on a worker stop the program with a located message. Shared
counters go through Sync.add, shared totals behind a Sync.mutex.
Example
program Squares {
function square(i: int, out: words) -> void { out[i] = i * i }
entry {
let sq = words(20000)
Job.parallel_for(20000, fn square, sq)
print(sq[141])
}
}