Python和多处理……如何在主进程中调用函数？

2019年8月4日 162次阅读

我想在
python中实现一个异步回调样式函数…这是我想出的但我不知道如何实际返回主进程并调用该函数.

funcs = {} 

def runCallback(uniqueId):
    '''
    I want this to be run in the main process.
    '''
    funcs[uniqueId]()


def someFunc(delay, uniqueId):
    '''
    This function runs in a seperate process and just sleeps.  
    '''
    time.sleep(delay)

    ### HERE I WANT TO CALL runCallback IN THE MAIN PROCESS ###

    # This does not work... It calls runCallback in the separate process:
    runCallback(uniqueId)


def setupCallback(func, delay):
    uniqueId = id(func)
    funcs[uniqueId] = func
    proc = multiprocessing.Process(target=func, args=(delay, uniqueId))
    proc.start()
    return unqiueId

以下是我希望它的工作方式：

def aFunc():
    return None

setupCallback(aFunc, 10)
### some code that gets run before aFunc is called ###
### aFunc runs 10s later ###

这里有一个问题,因为我希望这有点复杂.基本上当主进程中的代码完成运行时…我想检查funcs dict然后运行任何尚未运行的回调.这意味着runCallback还需要从funcs dict中删除条目… funcs dict不与单独的进程共享,所以我认为runCallback需要在主进程中调用???

最佳答案 目前还不清楚为什么在这里使用多处理模块.

要在同一过程中调用具有延迟功能,可以使用threading.Timer.

threading.Timer(10, aFunc).start()

如果你想稍后取消回调,Timer有.cancel()方法：

t = threading.Timer(10, runCallback, args=[uniqueId, funcs])
t.start()
timers.append((t, uniqueId))
# do other stuff
# ...
# run callbacks right now
for t, uniqueId in timers:
    t.cancel() # after this the `runCallback()` won't be called by Timer()
               # if it's not been called already
    runCallback(uniqueId, funcs)

修改runCallback()以删除要调用的函数：

def runCallback(uniqueId, funcs):
    f = funcs.pop(uniqueId, None) # GIL protects this code with some caveats
    if f is not None:
       f()
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