Python 多線程

2019-11-06 06:36:52

字體：大中小

來源：轉載

供稿：網友

Threading

Python的標準庫提供了兩個模塊：thread和threading，thread是低級模塊，threading是高級模塊，對thread進行了封裝。絕大多數情況下，我們只需要使用threading這個高級模塊。

啟動一個線程就是把一個函數傳入并創建Thread實例，然后調用start()開始執行：

import time,threadingdef loop(): 輸出結果：

thread MainThread is running… thread LoopThread is running… thread LoopThread >>> 1 thread LoopThread >>> 2 thread LoopThread >>> 3 thread LoopThread >>> 4 thread LoopThread >>> 5 thread LoopThread ended. thread MainThread ended.

由于任何進程默認就會啟動一個線程，我們把該線程稱為主線程，主線程又可以啟動新的線程，Python的threading模塊有個current_thread()函數，它永遠返回當前線程的實例。主線程實例的名字叫MainThread，子線程的名字在創建時指定，我們用LoopThread命名子線程。名字僅僅在打印時用來顯示，完全沒有其他意義，如果不起名字Python就自動給線程命名為Thread-1，Thread-2……

Lock

import threading# 3.lock# 假定這是你的銀行存款:balance = 0lock = threading.Lock()def change_it(n): # 先存后取，結果應該為0: global balance balance = balance + n balance = balance - ndef run_thread(n): for i in range(100000): lock.acquire() try: change_it(n) finally: lock.release()t1 = threading.Thread(target=run_thread, args=(5,))t2 = threading.Thread(target=run_thread, args=(8,))t1.start()t2.start()t1.join()t2.join()print balance

Queue

from random import randintfrom time import sleepfrom Queue import Queuefrom myThread import MyThreaddef writeQ(queue): print 'producing object for Q...', queue.put('xxx', 1) print "size now", queue.qsize()def readQ(queue): val = queue.get(1) print 'consumed object from Q... size now', / queue.qsize()def writer(queue, loops): for i in range(loops): writeQ(queue) sleep(randint(1, 3))def reader(queue, loops): for i in range(loops): readQ(queue) sleep(randint(2, 5))funcs = [writer, reader]nfuncs = range(len(funcs))def main(): nloops = randint(2, 5) q = Queue(32) threads = [] for i in nfuncs: t = MyThread(funcs[i], (q, nloops), / funcs[i].__name__) threads.append(t) for i in nfuncs: threads[i].start() for i in nfuncs: threads[i].join() print 'all DONE'if __name__ == '__main__': main()

starting writer at: Mon Mar 06 16:34:51 2017 add for Q… size now= 1 starting reader at: Mon Mar 06 16:34:51 2017 sub from Q… size now= 0 add for Q… size now= 1 sub from Q… size now= 0 add for Q… size now= 1 add for Q… size now= 2 writer finished at: Mon Mar 06 16:34:57 2017 sub from Q… size now= 1 sub from Q… size now= 0 reader finished at: Mon Mar 06 16:35:06 2017 all DONE

參考文獻： http://www.tuicool.com/articles/v QQNbiz

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