进程状态：创建、准备、运行、阻塞、结束
进程间的通信方拾：文件、管道、socket、信号、信号量、共享内存
python中创建进程的几种方式：
os.fork
subprocess
processing
multiprocessing
multiprocessing:
from multiprocessing import Process
from time import sleep
def task1():
while True:
sleep(1)
print("task1")
def task2():
while True:
sleep(1)
print("task2")
if __name__ == '__main__':
p1 = Process(target=task1)
p2 = Process(target=task2)
p1.start()
p2.start()
