对主进程的多处理回调 - Python

Question

有什么方法可以使用多处理从创建的进程回调主进程吗？假设我有 main.py 使用多处理创建三个进程，如下所示

from multiprocessing import Process
from child import createNewProcess

def callbackFunction(data):
   print(data)

if __name__ == "__main__"
   process = []
   for i in range(3):
        p = Process(target=createNewProcess, args=(callback,))
        process.append(p)
   [x.start() for x in process]

而且child.py看起来像

def createNewProcess(externalCB):
    # do something and call external callback
    data = 10 + 12
    externalCB(data)

我想调用 callbackFunction() ，它在创建的进程的主进程上下文中可用。但在上面的例子中，它在自己的进程中创建了三个新的 callbackFunction() 对象，并调用在自己的上下文中的对象。

如何使用多处理进程调用主 callbackFunction() 上下文？

Answer 1

带有使用队列传递适当回调并将数据返回到主进程线程的示例的代码段：

from multiprocessing import Process, Queue, current_process
from threading import Thread
from time import sleep

def foo_process(data, cb_queue, cb):
    print(f"data from process [{current_process().pid}]: {data}")
    sleep(.1) # time to flush stdout so print statement is usually in correct order
              # (may still be out of order on IPython)
    cb_queue.put((cb, data))

def foo_thread(data):
    print(f"data from cb_thread in process [{current_process().pid}]: {data*2}")

def callback_caller(cb_queue):
    for func, *args in iter(cb_queue.get, None): #pass None to exit thread
        func(*args)

if __name__ == "__main__":
    print(f"main pid: [{current_process().pid}]")
    q = Queue()

    p = Process(target=foo_process, args=(3.15, q, foo_thread))
    p.start()
    
    #It's advisable (if possible) to always create processes first then threads.
    #this primarily applies to using "fork", but it's good to know / good habit.
    t = Thread(target=callback_caller, args=(q,))
    t.start()

    p.join()

    q.put(None) #send shutdown signal to callback_caller
    t.join()

对主进程的多处理回调 - Python

Multiprocessing Callbacks to Main Process - Python

python

multithreading

callback

multiprocessing