多线程 VS 多进程
- 程序：一堆代码以文本形式存入一个文档
- 进程：程序运行的一个状态
- 包含地址空间，内存，数据栈
- 每个进程有自己完全独立的运行环境，多进程共享数据是一个问题
- 线程
- 一个进程的独立运行片段，一个进程可以有多个线程
- 轻量化的进程
- 一个进程的多个线程间共享数据和上下文运行环境
- 共享互斥问题
- 全局解释器锁（GIL）
- python代码的执行是由python虚拟机进行控制
- 在主循环中只能有一个控制线程在执行
- python包
- thread：有问题，不好用，python3版本改成了_thread
- threading:通行的包
'''
利用time函数，生成两个函数
顺序调用
计算总的运行时间
'''
import time
def loop1():
print('Start loop 1 at :', time.ctime())
time.sleep(4)
print('End loop 1 at:', time.ctime())
def loop2():
print('Start loop 2 at :', time.ctime())
time.sleep(2)
print('End loop 2 at:', time.ctime())
def main():
print("Starting at:", time.ctime())
loop1()
loop2()
print("All done at:", time.ctime())
if __name__ == '__main__':
main()
Starting at: Tue Jan 1 11:08:36 2019
Start loop 1 at : Tue Jan 1 11:08:36 2019
End loop 1 at: Tue Jan 1 11:08:40 2019
Start loop 2 at : Tue Jan 1 11:08:40 2019
End loop 2 at: Tue Jan 1 11:08:42 2019
All done at: Tue Jan 1 11:08:42 2019
'''
利用time函数，生成两个函数
顺序调用
计算总的运行时间
使用多线程，缩短总时间，使用_thread
'''
import time
import _thread as thread
def loop1():
print('Start loop 1 at :', time.ctime())
time.sleep(4)
print('End loop 1 at:', time.ctime())
def loop2():
print('Start loop 2 at :', time.ctime())
time.sleep(2)
print('End loop 2 at:', time.ctime())
def main():
print("Starting at:", time.ctime())
thread.start_new_thread(loop1, ())
thread.start_new_thread(loop2, ())
print("All done at:", time.ctime())
if __name__ == '__main__':
main()
while True:
time.sleep(1)
Starting at: Tue Jan 1 11:15:30 2019
All done at: Tue Jan 1 11:15:30 2019
Start loop 1 at : Tue Jan 1 11:15:30 2019
Start loop 2 at : Tue Jan 1 11:15:30 2019
End loop 2 at: Tue Jan 1 11:15:32 2019
End loop 1 at: Tue Jan 1 11:15:34 2019
import time
import _thread as thread
def loop1(in1):
print('Start loop 1 at :', time.ctime())
print("我是参数 ",in1)
time.sleep(4)
print('End loop 1 at:', time.ctime())
def loop2(in1, in2):
print('Start loop 2 at :', time.ctime())
print("我是参数 " ,in1 , "和参数 ", in2)
time.sleep(2)
print('End loop 2 at:', time.ctime())
def main():
print("Starting at:", time.ctime())
thread.start_new_thread(loop1,("王老大", ))
thread.start_new_thread(loop2,("王大鹏", "王晓鹏"))
print("All done at:", time.ctime())
if __name__ == "__main__":
main()
while True:
time.sleep(10)
- threading的使用
- 直接使用threading.Thread生成Thread实例
- 1.t = threading.Thread(target = xxx, args=(xxx, )) #target是函数名，args是参数
- 2.t.start() #气动多线程
- 3.t.join():等待多线程执行完成
- 守护线程，deamon
- 如果在程序中将子线程设置成守护线程，则子线程会在主线程结束的时候自动退出
- 一般认为，守护线程不重要或者不允许离开主线程独立运行
- 守护线程案例能否有效果跟环境相关
- 线程常用属性
- threading.currentThread:返回当前线程变量
- threading.enumerate:返回一个包含正在运行的线程的list，正在运行的线程指的是线程启动后，结束前的线程
- threading.ativeCount:返回正在运行的线程数量，效果跟len(threading.enumerate)相同
- thr.setName:给线程设置名字
- thr.getName:得到线程的名字
import time
import threading
def loop1(in1):
print('Start loop 1 at :', time.ctime())
print("我是参数 ",in1)
time.sleep(4)
print('End loop 1 at:', time.ctime())
def loop2(in1, in2):
print('Start loop 2 at :', time.ctime())
print("我是参数 " ,in1 , "和参数 ", in2)
time.sleep(2)
print('End loop 2 at:', time.ctime())
def main():
print("Starting at:", time.ctime())
t1 = threading.Thread(target=loop1, args=("王老大",))
t1.start()
t2 = threading.Thread(target=loop2, args=("王大鹏", "王小鹏"))
t2.start()
print("All done at:", time.ctime())
if __name__ == "__main__":
main()
while True:
time.sleep(10)
import time
import threading
def loop1(in1):
print('Start loop 1 at :', time.ctime())
print("我是参数 ",in1)
time.sleep(4)
print('End loop 1 at:', time.ctime())
def loop2(in1, in2):
print('Start loop 2 at :', time.ctime())
print("我是参数 " ,in1 , "和参数 ", in2)
time.sleep(2)
print('End loop 2 at:', time.ctime())
def main():
print("Starting at:", time.ctime())
t1 = threading.Thread(target=loop1, args=("王老大",))
t1.start()
t2 = threading.Thread(target=loop2, args=("王大鹏", "王小鹏"))
t2.start()
t1.join()
t2.join()
print("All done at:", time.ctime())
if __name__ == "__main__":
main()
while True:
time.sleep(10)
import time
import threading
def fun():
print("Start fun")
time.sleep(2)
print("end fun")
print("Main thread")
t1 = threading.Thread(target=fun, args=() )
t1.start()
time.sleep(1)
print("Main thread end")
import time
import threading
def fun():
print("Start fun")
time.sleep(2)
print("end fun")
print("Main thread")
t1 = threading.Thread(target=fun, args=() )
t1.setDaemon(True)
t1.start()
time.sleep(1)
print("Main thread end")
import time
import threading
def loop1():
print('Start loop 1 at :', time.ctime())
time.sleep(6)
print('End loop 1 at:', time.ctime())
def loop2():
print('Start loop 2 at :', time.ctime())
time.sleep(1)
print('End loop 2 at:', time.ctime())
def loop3():
print('Start loop 3 at :', time.ctime())
time.sleep(5)
print('End loop 3 at:', time.ctime())
def main():
print("Starting at:", time.ctime())
t1 = threading.Thread(target=loop1, args=( ))
t1.setName("THR_1")
t1.start()
t2 = threading.Thread(target=loop2, args=( ))
t2.setName("THR_2")
t2.start()
t3 = threading.Thread(target=loop3, args=( ))
t3.setName("THR_3")
t3.start()
time.sleep(3)
for thr in threading.enumerate():
print("正在运行的线程名字是： {0}".format(thr.getName()))
print("正在运行的子线程数量为： {0}".format(threading.activeCount()))
print("All done at:", time.ctime())
if __name__ == "__main__":
main()
while True:
time.sleep(10)
import threading
import time
class MyThread(threading.Thread):
def __init__(self, arg):
super(MyThread, self).__init__()
self.arg = arg
def run(self):
time.sleep(2)
print("The args for this class is {0}".format(self.arg))
for i in range(5):
t = MyThread(i)
t.start()
t.join()
print("Main thread is done!!!!!!!!")
import threading
from time import sleep, ctime
loop = [4,2]
class ThreadFunc:
def __init__(self, name):
self.name = name
def loop(self, nloop, nsec):
'''
:param nloop: loop函数的名称
:param nsec: 系统休眠时间
:return:
'''
print('Start loop ', nloop, 'at ', ctime())
sleep(nsec)
print('Done loop ', nloop, ' at ', ctime())
def main():
print("Starting at: ", ctime())
t = ThreadFunc("loop")
t1 = threading.Thread( target = t.loop, args=("LOOP1", 4))
t2 = threading.Thread( target = ThreadFunc('loop').loop, args=("LOOP2", 2))
t1.start()
t2.start()
t1.join( )
t2.join()
print("ALL done at: ", ctime())
if __name__ == '__main__':
main()
112
