python 多线程的启动与阻塞

import threading
t1=threading.Thread(target=func,args=iterable)
t2=threading.Thread(target=func,args=iterable)

创建一个新的进程很简单，func为想要进程执行的函数名，arg即为iterable
如func的参数为整数，传递参数的时候不能写成

t1=threading.Thread(target=func,args=3)

正确的写法为

#能用于for循环的即是iterable
t1=threading.Thread(target=func,args=（3，）)

启动线程

import time
import threading
def hold1(limit):
    i=0
    while i<limit:
        i+=1
        print(t1.name,"is runing")
        time.sleep(1)
    print(t1.name,"is over")
def hold2(limit):
    i=0
    while i<limit:
        i+=1
        print(t2.name,"is runing")
        time.sleep(1)
    print(t2.name,"is over")

start_time=time.time()
t1=threading.Thread(target=hold1,args=(3,))
t2=threading.Thread(target=hold2,args=(6,))

t1.start()
t2.start()

print(threading.current_thread().name,"耗时",time.time()-start_time)

输出为：
Thread-1 is runing
Thread-2 is runing
MainThread 耗时 0.002000093460083008
Thread-1 is runing
Thread-2 is runing
Thread-1 is runing
Thread-2 is runing
Thread-1 is over
Thread-2 is runing
Thread-2 is runing
Thread-2 is runing
Thread-2 is over

可以看出主线程先于子线程结束，若要主线程等待子线程，则需要join（）函数
在源代码的基础上，在t2.start()加入

t1.join()
t2.join()

则输出结果为：
Thread-1 is runing
Thread-2 is runing
Thread-2 is runing
Thread-1 is runing
Thread-2 is runing
Thread-1 is runing
Thread-2 is runing
Thread-1 is over
Thread-2 is runing
Thread-2 is runing
Thread-2 is over
MainThread 耗时 6.003343343734741