[util.multiprocessing] Unable to pass Queue to pool.apply_async

[zewenli98]

When using from ray.util.multiprocessing import Pool, I cannot pass a Queue to pool.apply_async. However, if from multiprocessing import Pool is used, there's no problem.

from multiprocessing import Process, Manager
from ray.util.multiprocessing import Pool

def async_evaluate(number, unevaluated_queue, evaluated_queue):
    print("entered async_evaluate")
    while True:
        sol = unevaluated_queue.get(block=True, timeout=None)
        # objective1.eval(sol)
        evaluated_queue.put(sol, block=True, timeout=None)

unevaluated_queue = Manager().Queue()
evaluated_queue = Manager().Queue()

pool = Pool()
pool.apply_async(func=async_evaluate, args=(666, unevaluated_queue, evaluated_queue,))

As above, I'm sure that some processes are started, but print("entered async_evaluate") is not executed. The problem is that these codes can be run correctly in Pool class of multiprocessing. Is there anything wrong(BUG) with Pool class in Ray?