python 多線程 start_new_thread()

標籤：python   多線程   

一、簡述

　　CPython實現細節： 由於GIL（Global Interpreter Lock），在CPython中一次只能有一個線程來執行python代碼，不過有些面向執行的庫可以克服這個限制。如果想要使你的應用程式更好的利用電腦資源的話，最好使用multiprocessing。 但是，如果同時運行多個I/O任務的話，線程依然是一個很好地選擇。
　　python線程的作用主要是應對I/O任務，例如網路資料的讀寫等。

二、樣本

　　1. 函數說明。
　　start_new_thread ( function , args [ , kwargs ] )
　　建立一個新的線程，返回一個線程標識符。function是線程函數，args是線程函數的參數，是一個list。kwargs選擇性參數，可不填。

#!/usr/bin/env python# _*_ coding = utf-8 _*_import threadimport timedef work_thread(id):    cnt = 1    print "Thread %d is runing..." % id    while True:        print "Thread with ID %d has counter value %d" % (id, cnt)        time.sleep(2)         cnt += 1for i in range(1,5):    thread.start_new_thread(work_thread,(i,))print "Main thread doing an infinite wait loop..."while True:    pass

運行代碼，輸出結果如下：

$ ./thread_demo.py
Main thread doing an infinite wait loop…
Thread 3 is runing…
Thread 1 is runing…
Thread 2 is runing…
Thread 4 is runing…
Thread with ID 1 has counter value 1
Thread with ID 4 has counter value 1
Thread with ID 2 has counter value 1
Thread with ID 3 has counter value 1
Thread with ID 2 has counter value 2
Thread with ID 3 has counter value 2
Thread with ID 4 has counter value 2
Thread with ID 1 has counter value 2
Thread with ID 3 has counter value 3
Thread with ID 4 has counter value 3
Thread with ID 1 has counter value 3
Thread with ID 2 has counter value 3
Thread with ID 1 has counter value 4
Thread with ID 4 has counter value 4
Thread with ID 2 has counter value 4
Thread with ID 3 has counter value 4

線程退出函數：
thread.exit ()。結束當前線程。調用該函數會觸發 SystemExit 異常，如果沒有處理該異常，線程將結束。

python 多線程 start_new_thread()