进程和线程的三大区别

#创建进程的开销远大于开启线程的开销
from threading import Thread
from multiprocessing import Process
import time
def task(name):
    print('代双华吃%s
'%name)
    time.sleep(3)
    print('代双华吃%s'%name)
if __name__ =="__main__":
    # p = Process(target=task, args=('鸟屎', ))
    # p.start()
    t = Thread(target=task, args=('鸟屎', ))
    t.start()
    print('主')


# 同一进程内的所有线程共享此进程内的地址空间
from threading import Thread
from multiprocessing import Process
n = 100
def task():
    global n
    n = 0
if __name__ =="__main__":
    p = Process(target=task)
    p.start()
    p.join()
    # t = Thread(target=task)
    # t.start()
    # t.join()
    print('主', n)

# 瞅PID
  # 查看进程pid
from multiprocessing import Process, current_process  #current_process只可以查看pid不可以查看ppid（父进程的pid）
import os
def task():
    print('子进程的PID是%s,父进程的PID是%s'%(os.getpid(), os.getppid()))
if __name__ =="__main__":
    p = Process(target=task)
    p.start()
    print('主', os.getpid())
    # 查看线程pid（为了方便理解暂称子线程）
from threading import Thread, current_thread   #current_Thread可以查看pid同os模块的os.getpid()
import os
def task():
    print('子线程的PID是%s' % (os.getpid()))
if __name__ =="__main__":
    t = Thread(target=task)
    t.start()
    t.join()
    print('主', os.getpid())