Python学习笔记之线程

from multiprocessing import Process
import time
import os
class MyProcess(Process):
    def __init__(self, name):  ##重写，需要__init__,也添加了新的参数。        ##Process.__init__(self) 不可以省略，否则报错：AttributeError:'XXXX'object has no attribute '_colsed'
        Process.__init__(self)
        self.name = name
    def run(self):
        print("子进程(%s-%s)启动" % (self.name, os.getpid()))
        time.sleep(3)
        print("子进程(%s-%s)结束" % (self.name, os.getpid()))
if __name__ == '__main__':
    print("父进程启动")
    p = MyProcess("Ail")
    # 自动调用MyProcess的run()方法
    p.start()
    p.join()
    print("父进程结束")

from threading import Thread
from multiprocessing import Process
import os
def work():
    print('hello,',os.getpid())
if __name__ == '__main__':
    # 在主进程下开启多个线程，每个线程都跟主进程的pid一样
    t1 = Thread(target=work)  # 开启一个线程
    t2 = Thread(target=work)  # 开启两个线程
    t1.start()  ##start()--It must be called at most once per thread object.It arranges for the object's run() method to be                ## invoked in a separate thread of control.This method will raise a RuntimeError if called more than once on the                ## same thread object.
    t2.start()
    print('主线程/主进程pid', os.getpid())
    # 开多个进程，每个进程都有不同的pid
    p1 = Process(target=work)
    p2 = Process(target=work)
    p1.start()
    p2.start()
    print('主线程/主进程pid',os.getpid())

import time
import threading
class MyThread(threading.Thread):
    def __init__(self,num):
        super().__init__() ###或者是Thread.__init__()
        self.num = num
    def run(self):
        print('线程名称：', threading.current_thread().getName(), '参数：', self.num, '开始时间：', time.strftime('%Y-%m-%d %H:%M:%S'))
if __name__ == '__main__':
    print('主线程开始：',time.strftime('%Y-%m-%d %H:%M:%S'))
    t1 = MyThread(1)
    t2 = MyThread(2)
    t1.start()
    t2.start()
    t1.join()
    t2.join()
    print('主线程结束：', time.strftime('%Y-%m-%d %H:%M:%S'))

from threading import Thread
from threading import Lock
import time
number = 0
def task(lock):
    global number
    lock.acquire() ##持有锁
    for i in range(100000)      number += 1
    lock.release() ##释放锁
if __name__ == '__main__':
    lock=Lock()
    t1 = Thread(target=task,args=(lock,))
    t2 = Thread(target=task,args=(lock,))    t3 = Thread(target=task,args=(lock,))
    t1.start()    t2.start()    t3.start()    t1.join()    t2.join()    t3.join()        print('number:',number)

import time
import threading
s=threading.Semaphore(5)    #添加一个计数器
def task():
    s.acquire()    #计数器获得锁
    time.sleep(2)    #程序休眠2秒
    print("The task run at ",time.ctime())
    s.release()    #计数器释放锁

for i in range(40):
    t1=threading.Thread(target=task,args=())    #创建线程
    t1.start()    #启动线程

import time
import threading
s=threading.Semaphore(5)    #添加一个计数器
def task():    with s:   ## 类似打开文件的with操作
    ##s.acquire()    #计数器获得锁
      time.sleep(2)    #程序休眠2秒
      print("The task run at ",time.ctime())
    ##s.release()    #计数器释放锁

for i in range(40):
    t1=threading.Thread(target=task,args=())    #创建线程
    t1.start()    #启动线程