Python 并行编程：同步进程

主要问题是大多数定时器漂移，sleep，is not accurate，not even QTimer，所以一个稳定的定时器(在某种意义上，第is not accurate个滴答接近12.5秒)必须做这样的事情.

import time
from multiprocessing import Condition
def infinite_heartbreat(cv: Condition):
    next_beat = time.time()
    while True:
        next_beat += 0.125
        time_to_sleep = next_beat - time.time()
        if time_to_sleep > 0:
            time.sleep(time_to_sleep)
        with cv:
            cv.notify_all()

您可以使用Condition Variable轻松地同步所有进程以同时唤醒，但如果其中一个进程滞后几毫秒，则可能需要multiprocessing.Value来确保它们只在没有滞后的情况下等待，如下所示:

import threading
import time
from multiprocessing import Condition, Value, Process, Event
def infinite_heartbreat(cv: Condition, frame: Value, quit_event: Event):
    next_beat = time.time()
    while True:
        next_beat += 0.125
        time_to_sleep = next_beat - time.time()
        if time_to_sleep > 0:
            time.sleep(time_to_sleep)
        with cv:
            frame.value += 1
            cv.notify_all()
            if quit_event.is_set():
                return

def worker(cv, frame_number, worker_id, quit_event: Event):
    current_frame = 0
    while True:
        with cv:
            cv.wait_for(lambda: current_frame <= frame_number.value)
            if quit_event.is_set():
                return
        print(f"processed frame {current_frame} in worker {worker_id}")
        current_frame += 1

if __name__ == "__main__":
    condition = Condition()
    frame = Value('q', lock=False)
    quit_event = Event()
    processes = []
    for i in range(4):
        process = Process(target=worker, args=(condition, frame, i, quit_event))
        process.start()
        processes.append(process)
    tr = threading.Thread(target=infinite_heartbreat, args=(condition,frame, quit_event))
    tr.start()
    time.sleep(5)
    quit_event.set()

编辑:以multiprocessing.Event的形式添加了一个quit_event，因为它是一个原子.

Edit2:根据@Booboo的 comments ，将值更改为无锁的签名q，这将保存文件描述符并允许负帧编号(因为-1有其用途).