threading伪多线程

import threading, time def run(n):     print("task", n)     time.sleep(2)  t1 = threading.Thread(target=run, args=("t1",)) t2 = threading.Thread(target=run, args=("t2",)) t1.start() t2.start() run("t1") run("t2")  import threading, time class MyThread(threading.Thread):     def __init__(self, n):         super(MyThread, self).__init__()         self.n = n     def run(self):         print("running task", self.n)         time.sleep(2) t1 = MyThread("t1") t2 = MyThread("t2")  t1.run() t2.run() t1.start() t2.start()  import threading, time def run(n):     print("task", n)     time.sleep(2)     print("task done", n, threading.current_thread())  # 打印子线程  start_time = time.time() t_objs = [] for i in range(50):     t = threading.Thread(target=run, args=("t %s" % i,))     t.start()     t_objs.append(t)  # 把每个线程实例都加进来 不阻塞后面线程的启动 for t in t_objs:  # 取列表里的每个线程     t.join()  # 等待并行的每个线程全都执行完毕 在往下走  print("----all threads has finished...", threading.current_thread(), threading.active_count())  # 打印主线程，程序默认有一个主线程 print("cost:", time.time() - start_time)  # threading.active_count()活跃线程个数  import time,threading  import time,threading class MyThread(threading.Thread):     def __init__(self, n, sleep_time):         super(MyThread, self).__init__()         self.n = n         self.sleep_time = sleep_time      def run(self):         print("running task", self.n)         time.sleep(self.sleep_time)         print("task done", self.n)   t1 = MyThread("t1", 2)  # 等待2秒 t2 = MyThread("t2", 4)  # 等待4秒 t1.start() t2.start() t1.join()  # wait() 等待t1线程执行完再往下走 程序进程变成串行了 主程序卡主了 t2.join()  # t1执行完之后等t2 等待t2 执行完之后再往下走 print("main threading....") # 程序末尾有一个默认的join 守护线程  import threading, time def run(n):     print("task", n)     time.sleep(2)     print("task done", n, threading.current_thread())  # 打印子线程 如果不设置为守护线程，那么程序会执行到这里 start_time = time.time() t_objs = [] for i in range(50):     t = threading.Thread(target=run, args=("t %s" % i,))     t.setDaemon(True)  # 设置为守护线程 设置为守护线程之后，主线程执行完之后程序就退出了，不管守护线程有没有执行完都会退出     t.start()     t_objs.append(t)  # 把每个线程实例都加进来 不阻塞后面线程的启动 # for t in t_objs: #取列表里的每个线程 #    t.join() #等待并行的每个线程全都执行完毕 在往下走  print("----all threads has finished...") print("cost:", time.time() - start_time)