python - 如何确定带有队列的 Python 线程是否完成任务？

Question

这里我有 MazeRunner 类，它将 self.boxes 的所有元素放入队列中，并在它们上运行线程，直到所有队列都变空 q.empty () .

Here problem is how do i actually identify if my program is done performing threads on all elements which are in queue of self.boxes & return True.

这看起来很有挑战性，因为 我们的线程 处于 while 循环中，它根据我们定义的 self.boxes 长度和 self.threads 保持变化。我已经尝试将所有线程放入列表中，然后将它们全部t.join。但不是运气。有什么帮助吗？

import threading,queue,time 

class MazeRunner:
    def __init__(self):
        self.q = queue.Queue()
        self.boxes = [1,2,3,4,5,6,7] ## `7` elements of list
        self.threads = 5

        for i in self.boxes:
            self.q.put(i) ### ADDING Every element of list to queue

        for j in range(self.threads): ### for i in range(5)  threads
            t = threading.Thread(target=self.ProcessQueue)
            t.start() ### Started `5` threads on `7` elements

    def ProcessQueue(self):
        while not self.q.empty():
            each_element = self.q.get()
            self.SleepFunction(each_element)
            self.q.task_done()

    def SleepFunction(self,each_element):
        print("STARTING : ",each_element)
        time.sleep(10)
        print("DONE : ",each_element)

---

lets_try = MazeRunner()
if lets_try == True:
     print("All Threads Done on Elements")

Answer 1

您需要等到所有线程都完成调用 Thread.join :

操作方法:

• 用类常量替换您的 self.threads = 5 表达式:

  THREAD_NUM = 5
  

• 将附加属性 threads(用于线程列表)放入您的 __init__ 方法中:

  ...
  self.threads = []
  

• 将每个创建的线程放入threads列表中:

  for j in range(self.THREAD_NUM):
      t = threading.Thread(target=self.ProcessQueue)
      self.threads.append(t)
      t.start()
  

• 定义方法，如 check_completed 以确保所有线程都已终止(完成):

  ....
  
  def check_completed(self):
      for t in self.threads:
          t.join()
      return True
  

您需要检查“全部完成”的方式:

m_runner = MazeRunner()
if m_runner.check_completed():
    print("All Threads Done on Elements")