python 简单的多线程代码

import threading
import time
class my_first_threading(threading.Thread):
    string=""
    def __init__(self,name,counter,Thread_id,string):
        threading.Thread.__init__(self)
        self.counter=counter
        self.name=name
        self.Thread_id=Thread_id
        self.string=string
    def run(self):
        print("<---"+self.name+"begin--->\n")
        print_string(self.name,self.string,self.counter)
        print("<---"+self.name+"out--->\n")
def print_string(name,string,counter):
    for i in range(counter):
        print(str(i+1)+". "+name+" :"+string+"\n")
        time.sleep(0.2)
def main():
    start_time=time.time()
    string1=input("\n\n\n第一个进程需要打印的字符串：")
    time_1=int(input("进程需要运行的次数 time: "))
    string2=input("\n第二个进程需要打印的字符串：")
    time_2=int(input("进程需要运行的次数 time: "))
    print("\n\n\n\n")
    th1=my_first_threading("进程一",time_1,1314,string1)
    th2=my_first_threading("进程二",time_2,3344,string2)
    start1_time=time.time()    
    th1.start()
    th1.join()
    print("\n\n||--->子线一程束，耗时 "+str(time.time()-start1_time)+"秒<---||\n\n")
    start2_time=time.time()
    th2.start()
    th2.join()
    print("\n\n||--->子线二程束，耗时 "+str(time.time()-start2_time)+"秒<---||\n")
    print("\n\n||--->主线程结束，耗时 "+str(time.time()-start_time)+"秒<---||\n\n")
    return 1
if __name__ == "__main__":
    main()