多线程与线程数控制

#!/usr/bin/python 
#coding:utf-8 
import threading 
import datetime 
import logging 
import time
import random

logging.basicConfig(level = logging.DEBUG,format='(%(threadName)-10s) %(message)s',) 
list = ['192.168.0.0', '192.168.0.1', '192.168.0.2', '192.168.0.3', '192.168.0.4', '192.168.0.5', '192.168.0.6', '192.168.0.7', '192.168.0.8', '192.168.0.9',
 '192.168.0.10', '192.168.0.11', '192.168.0.12', '192.168.0.13', '192.168.0.14', '192.168.0.15', '192.168.0.16', '192.168.0.17', '192.168.0.18']
class Test(threading.Thread): 
    def __init__(self,threadingSum, ip): 
        threading.Thread.__init__(self) 
        self.ip = ip 
        self.threadingSum = threadingSum 
                                                              
    def run(self): 
        with self.threadingSum: 
            logging.debug("%s start!" % self.ip) 
            time.sleep(random.randint(1,3)) 
            logging.debug('%s Done!' % self.ip) 
                                                                  
                                                              
if __name__ == "__main__": 
    #设置线程数 
    threadingSum = threading.Semaphore(3) 
                                                          
    #启动线程 
    for ip in list: 
        t = Test(threadingSum,ip) 
        t.start() 
    #等待所有线程结束 
    for t in threading.enumerate(): 
        if t is threading.currentThread(): 
            continue
        t.join() 
                                                              
    logging.debug('Done!')