通过类创建子线程&同步锁

一、通过类创建子线程

 import threading
 class MyThread(threading.Thread):
     def __init__(self,num):
         threading.Thread.__init__(self)
         self.num = num
     def run(self):
         print('running on number %s' %self.num)
 if __name__ == '__main__':
     t1 = MyThread(1)
     t2 = MyThread(2)
     t1.start()
     t2.start()

二、同步锁

import time
import threading
def cal():
    global num
    r.acquire()      #上锁
    temp = num
    time.sleep(0.001)
    num = temp-1
    r.release()      #开锁

1.被上锁的代码不执行完，GIL锁不释放，线程不切换
2.开锁后，多线程正常运行

 num = 100
 thread_list = []
 r = threading.Lock()    #创建锁
 for i in range(100):
     t = threading.Thread(target=cal)
     t.start()
     thread_list.append(t)

 for t in thread_list:    #等待所有子线程执行完毕
     t.join()

 print(num)