python windows上调用subprogress

#由于windows不支持os.wait()，系统会不停的创建进程， 这里使用一个sets()作为一个池，控制进程的数量，使用subprogress 调用外部命令完成工作








#-*- coding:utf-8-*-





import os





import subprocess





import time








pids = []





n = 0








ps = set()





max_p = 20








for i in open("imgurlok.txt","r").readlines():





    (num,name,url) = i.split("|||")





    dirname = "f:/ooo/img5/"+str(num)+"/"





    if not os.path.exists(dirname):





        os.mkdir(dirname)





    cmd = "wget -t3 -T5 " + " -P "+ dirname.encode("gbk","ignore") + "  "+url+" > nul"





    p = subprocess.Popen(cmd,stdin=None,stdout=None, shell=True)





    ps.add(p)





    while len(ps) >= max_p:





        time.sleep(0.001)#这个值如果设置得当，可以不再下面进行异常捕获的操作





        try:





            ps.difference_update(d for d in ps if d.poll() is not None)





        except:





            pass