Question

这是代码，这些是虚拟类，最终会被更有用的东西取代。我想要while循环做的是从队列中提取数据以查看毒丸是否被丢弃。如果不是，我想要触发else语句中的任何内容。但是由于某些原因，它会等到它获得一个毒丸并且只在声明

时才执行kill条件

class test_imports:#Test classes remove 

      def import_1(self, control_queue, thread_number):
          print ("Import_1 number %d started") % thread_number
          run = True
          count = 1
          while run == True:
                alive = control_queue.get()                
                count = count + 1
                if alive == 't1kill':#<==will trigger
                   print ("Killing thread type 1 number %d") % thread_number
                   run = False                   
                else:#<== won't trigger
                     print ("Thread type 1 number %d run count %d") % (thread_number, count)

如果需要，剩下的代码是：

import multiprocessing 
import time 

class test_imports:#Test classes remove 

      def import_1(self, control_queue, thread_number):
          print ("Import_1 number %d started") % thread_number
          run = True
          count = 1
          while run == True:
                alive = control_queue.get()                
                count = count + 1
                if alive == 't1kill':
                   print ("Killing thread type 1 number %d") % thread_number
                   run = False                   
                else:
                    print ("Thread type 1 number %d run count %d") % (thread_number, count)     



      def import_2(self, control_queue, thread_number):
          print ("Import_2 number %d started") % thread_number
          run = True
          count = 1
          while run == True:
                alive = control_queue.get()                   
                count = count + 1
                if alive == 't2kill':
                   print ("Killing thread type 2 number %d") % thread_number
                   run = False
                else:
                     print ("Thread type 2 number %d run count %d") % (thread_number, count)


class worker_manager:
     def __init__(self):
        self.children = {}

     def generate(self, control_queue, threadName, runNum):
        i = test_imports()
        if threadName == 'one':
            print ("Starting import_1 number %d") % runNum
            p = multiprocessing.Process(target=i.import_1, args=(control_queue, runNum))
            self.children[threadName] = p
            p.start()        
        elif threadName == 'two': 
            print ("Starting import_2 number %d") % runNum
            p = multiprocessing.Process(target=i.import_2, args=(control_queue, runNum))
            self.children[threadName] = p
            p.start()
        elif threadName == 'three':    
            p = multiprocessing.Process(target=i.import_1, args=(control_queue, runNum))
            print ("Starting import_1 number %d") % runNum
            p2 = multiprocessing.Process(target=i.import_2, args=(control_queue, runNum))
            print ("Starting import_2 number %d") % runNum
            self.children[threadName] = p
            self.children[threadName] = p2
            p.start()
            p2.start()

        else:
            print ("Not a valid choice choose one two or three")     

     def terminate(self, threadName):
         self.children[threadName].join


if __name__ == '__main__':
    # Establish communication queues
    control = multiprocessing.Queue()
    manager = worker_manager()

    runNum = int(raw_input("Enter a number: ")) 
    threadNum = int(raw_input("Enter number of threads: "))
    threadName = raw_input("Enter number: ")
    thread_Count = 0

    print ("Starting threads") 

    for i in range(threadNum):
        manager.generate(control, threadName, i)
        thread_Count = thread_Count + 1              

    time.sleep(runNum)#let threads do their thing

    print ("Terminating threads")     

    for i in range(thread_Count):
        control.put("t1kill")
        control.put("t2kill")

    manager.terminate(threadName)

请注意import_2与import_1相同，但打印的内容不同。关键是要证明处理不同线程类型的能力。

Answer 1

在您的驱动程序代码中，您首先control.put("t1kill")。

您t1kill的处理程序设置run = False，因此您不会再次通过while run == True循环返回。

因此，您的else无法被触发。

如果你想测试它，只需添加put个虚拟值：

for i in range(thread_Count):
    control.put("dummy")
    control.put("t1kill")
    control.put("t2kill")

但是，在真正的代码中，您可能希望manager.generate方法在队列中放置一些有用的值。

作为旁注，你使代码变得比它需要的更复杂。

首先，写while run == True:而不仅仅是while run:几乎总是一个坏主意。正如PEP 8的Programming Recommendations部分所说：

不要使用==。
将布尔值与True或False进行比较

但实际上，只要你完成就可以return，并完全取消run标志：

while True:
    alive = control_queue.get()                
    count = count + 1
    if alive == 't1kill':
        print ("Killing thread type 1 number %d") % thread_number
        return                   
    else:
        print ("Thread type 1 number %d run count %d") % (thread_number, count)

（有些人会告诉你break，早期return等是“糟糕的结构化编程”。但Python不是C。）

为什么我的python else语句不会触发？

1 个答案: