from time import sleep
import multiprocessing

# a function that blocks for a moment
def task():
    print("first")
    toMain.put(1)
    fromMain.get()
    print("third")

toMain = multiprocessing.Queue()
fromMain = multiprocessing.Queue()

# create a process
p = multiprocessing.Process(target=task)
# run the process
p.start()
sleep(1)
aa = toMain.get()
print(f"Second, get {aa} from sub process")
fromMain.put(2)
p.join()