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全面解析python线程优先级队列(queue)原理

程序员文章站 2022-03-16 19:01:47
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Python的Queue模块中提供了同步的、线程安全的队列类,包括FIFO(先入先出)队列Queue,LIFO(后入先出)队列LifoQueue,和优先级队列PriorityQueue。这些队列都实现了锁原语,能够在多线程中直接使用。可以使用队列来实现线程间的同步。

Queue模块中的常用方法:

1.Queue.qsize() 返回队列的大小

2.Queue.empty() 如果队列为空,返回True,反之False

3.Queue.full() 如果队列满了,返回True,反之False

4.Queue.full 与 maxsize 大小对应

5.Queue.get([block[, timeout]])获取队列,timeout等待时间

6.Queue.get_nowait() 相当Queue.get(False)

7.Queue.put(item) 写入队列,timeout等待时间

8.Queue.put_nowait(item) 相当Queue.put(item, False)

9.Queue.task_done() 在完成一项工作之后,Queue.task_done()函数向任务已经完成的队列发送一个信号

10.Queue.join() 实际上意味着等到队列为空,再执行别的操作

#!/usr/bin/python
# -*- coding: UTF-8 -*-
import Queue
import threading
import time
exitFlag = 0
class myThread (threading.Thread):
def __init__(self, threadID, name, q):
threading.Thread.__init__(self)
self.threadID = threadID
self.name = name
self.q = q
def run(self):
print "Starting " + self.name
process_data(self.name, self.q)
print "Exiting " + self.name
def process_data(threadName, q):
while not exitFlag:
queueLock.acquire()
if not workQueue.empty():
data = q.get()
queueLock.release()
print "%s processing %s" % (threadName, data)
else:queueLock.release()
time.sleep(1)
threadList = ["Thread-1", "Thread-2", "Thread-3"]
nameList = ["One", "Two", "Three", "Four", "Five"]
queueLock = threading.Lock()
workQueue = Queue.Queue(10)
threads = []
threadID = 1
# 创建新线程
for tName in threadList:
thread = myThread(threadID, tName, workQueue)
thread.start()
threads.append(thread)
threadID += 1
# 填充队列
queueLock.acquire()
for word in nameList:
workQueue.put(word)
queueLock.release()
# 等待队列清空
while not workQueue.empty():
pass
# 通知线程是时候退出
exitFlag = 1
# 等待所有线程完成
for t in threads:
t.join()
print "Exiting Main Thread"

以上程序执行结果:

Starting Thread-1
Starting Thread-2
Starting Thread-3
Thread-1 processing One
Thread-2 processing Two
Thread-3 processing Three
Thread-1 processing Four
Thread-2 processing Five
Exiting Thread-3
Exiting Thread-1
Exiting Thread-2
Exiting Main Thread

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