python多线程运行时只有一个现场,是怎么回事,源代码如下帮忙看下!

fu7100

ftp_ins=ftplib.FTP()
ftp_ins.connect(host='127.0.0.1',port=21)
ftp_ins.login(user='ftp',passwd='ftp')

ftp_lock=threading.Lock()
def dir_walk(root_path):
    dir_files = []
    ftp_lock.acquire()
    ftp_ins.cwd(root_path)
    ftp_ins.dir(root_path,dir_files.append)
    ftp_lock.release()
    for item in dir_files[2:]:
        file_type=item.split()[0][0]
        file_name=item.split()[8]
        if file_type=='d':
            if root_path=='/':
                dir_path=root_path+file_name
            else:
                dir_path=root_path+'/'+file_name
            dir_deque.append(dir_path)
        else:
             pass

#设置ftp根目录
root_path='/'
#创建一个队列
dir_deque = deque()
dir_deque.append(root_path)
#通过循环队列的方式获取每次的root_path
def thread_process():
    while True:
        try:
            root_path=dir_deque.popleft()
        except:
            break
        else:
            dir_walk(root_path)
        print threading.current_thread()
        time.sleep(0.5)
thread_num=2
threads=[]
num=0
for i in range(thread_num):
    threads.append(threading.Thread(target=thread_process))
    num+=1
    print 'num:',num

for t in threads:
    t.start()
for t in threads:
    t.join()


运行结果
"D:\Program Files\Python2.7\python.exe" E:/WrokSpace/guang_dong_6_hundred_million/script/ftp2.py
num: 1
num: 2
<Thread(Thread-1, started 7984)>
<Thread(Thread-1, started 7984)>
<Thread(Thread-1, started 7984)>
<Thread(Thread-1, started 7984)>
<Thread(Thread-1, started 7984)>
<Thread(Thread-1, started 7984)>
<Thread(Thread-1, started 7984)>