# so something like this
type
  Scheduler = object

var
  lock {.global.}: Lock
  queue_thr: Thread[Scheduler]
  queue {.global, guard: lock.}: Deque[string] = initDeque[string]()

initLock lock

proc sch_thread(sch: Scheduler) {.thread.} =
  {.cast(gcsafe).}:
    withLock lock:
      let str = "last"
      queue.addLast(str)

proc main =
  var sch: Scheduler
  createThread(queue_thr, sch_thread, sch)
  joinThread(queue_thr)
  withLock lock:
    echo queue

main()