最近引入了队列设计,关于延迟处理能力以及实现“FIFO”等.

查看文档以尝试获取示例队列,以了解如何在我自己的设计/程序中实现它.但我遇到运行此代码的问题：

import queue

def worker():

while True:

item = q.get()

do_work(item)

q.task_done()

def main():

q = queue.Queue(maxsize=0)

for i in range(num_worker_threads):

t = Thread(target=worker)

t.daemon = True

t.start()

for item in source():

q.put(item)

q.join() # block until all tasks are done

main()

问题：希望有人解释for循环正在做什么,我只是运行代码时出错,所以我不得不遗漏一些东西.

出现问题错误：

NameError：未定义全局名称’num_worker_threads’

谢谢-Python新手 –

for循环启动了许多工作线程来执行“worker”定义的功能.这是应该在python 2.7中运行在您的系统上的工作代码.

import Queue

import threading

# input queue to be processed by many threads

q_in = Queue.Queue(maxsize=0)

# output queue to be processed by one thread

q_out = Queue.Queue(maxsize=0)

# number of worker threads to complete the processing

num_worker_threads = 10

# process that each worker thread will execute until the Queue is empty

def worker():

while True:

# get item from queue, do work on it, let queue know processing is done for one item

item = q_in.get()

q_out.put(do_work(item))

q_in.task_done()

# squares a number and returns the number and its square

def do_work(item):

return (item,item*item)

# another queued thread we will use to print output

def printer():

while True:

# get an item processed by worker threads and print the result. Let queue know item has been processed

item = q_out.get()

print "%d squared is : %d" % item

q_out.task_done()

# launch all of our queued processes

def main():

# Launches a number of worker threads to perform operations using the queue of inputs

for i in range(num_worker_threads):

t = threading.Thread(target=worker)

t.daemon = True

t.start()

# launches a single "printer" thread to output the result (makes things neater)

t = threading.Thread(target=printer)

t.daemon = True

t.start()

# put items on the input queue (numbers to be squared)

for item in range(10):

q_in.put(item)

# wait for two queues to be emptied (and workers to close)

q_in.join() # block until all tasks are done

q_out.join()

print "Processing Complete"

main()

@handle的Python 3版本

import queue

import threading

# input queue to be processed by many threads

q_in = queue.Queue(maxsize=0)

# output queue to be processed by one thread

q_out = queue.Queue(maxsize=0)

# number of worker threads to complete the processing

num_worker_threads = 10

# process that each worker thread will execute until the Queue is empty

def worker():

while True:

# get item from queue, do work on it, let queue know processing is done for one item

item = q_in.get()

q_out.put(do_work(item))

q_in.task_done()

# squares a number and returns the number and its square

def do_work(item):

return (item,item*item)

# another queued thread we will use to print output

def printer():

while True:

# get an item processed by worker threads and print the result. Let queue know item has been processed

item = q_out.get()

print("{0[0]} squared is : {0[1]}".format(item) )

q_out.task_done()

# launch all of our queued processes

def main():

# Launches a number of worker threads to perform operations using the queue of inputs

for i in range(num_worker_threads):

t = threading.Thread(target=worker)

t.daemon = True

t.start()

# launches a single "printer" thread to output the result (makes things neater)

t = threading.Thread(target=printer)

t.daemon = True

t.start()

# put items on the input queue (numbers to be squared)

for item in range(10):

q_in.put(item)

# wait for two queues to be emptied (and workers to close)

q_in.join() # block until all tasks are done

q_out.join()

print( "Processing Complete" )

main()