Python之路，day10-Python基础
一、进程
进程：一个程序要运行时所需的所有资源的集合
进程是资源的集合，相当于一个车间
一个进程至少需要一个线程，这个线程为主线程
一个进程里可以有多个线程
cpu cores越多，代表着你可以真正并发的线程越多
2个进程之间的数据是完全独立的，互相不能访问
1.进程lock
1 from multiprocessing import Process, Lock 2 3 4 def f(l, i): 5 l.acquire() 6 try: 7 print('hello world', i) 8 finally: 9 l.release() 10 11 12 if __name__ == '__main__': 13 lock = Lock() 14 15 for num in range(10): 16 Process(target=f, args=(lock, num)).start()
2.进程池
1 from multiprocessing import Process, Lock,Pool 2 import time 3 4 def f(i): 5 # l.acquire() 6 # try: 7 print('hello world %s'%i) 8 time.sleep(1) 9 # finally: 10 # l.release() 11 return i 12 13 def Bar(data): 14 print(data) 15 if __name__ == '__main__': 16 lock = Lock() 17 pool = Pool(processes=5) 18 for num in range(10): 19 # Process(target=f, args=(lock, num)).start() 20 pool.apply_async(func=f,args=(num,),callback=Bar) 21 pool.close() 22 pool.join()
3.进程间通信
1 from multiprocessing import Process, Queue 2 3 4 def f(q): 5 q.put([42, None, 'hello']) 6 7 8 if __name__ == '__main__': 9 q = Queue() 10 p = Process(target=f, args=(q,)) 11 p.start() 12 print(q.get()) # prints "[42, None, 'hello']" 13 p.join()
3.多进程
1 from multiprocessing import Process 2 import time 3 4 5 def f(name): 6 time.sleep(2) 7 print('hello', name) 8 9 10 if __name__ == '__main__': 11 for i in range(10): 12 p = Process(target=f, args=('bob',)) 13 p.start() 14 # p.join()
二、线程
线程：
一个单一的指令的控制流，寄生在进程中
单一进程里的多个线程是共享数据的
多线程在涉及修改同一数据时一定要加锁
自己总结：（宏观并发，时间片切换比进程快），多核编程
1.线程
1 import threading 2 import time 3 def run(n): 4 time.sleep(1) 5 # print(threading.get_ident()) 6 print("thread",n) 7 print(threading.current_thread()) 8 for i in range(10): 9 t = threading.Thread(target=run, args=(i,)) 10 t.start() 11 # t.setName(i) 12 print(t.getName()) 13 14 print(threading.active_count()) 15 # t = threading.Thread(target=run,args=(1,)) 16 # t.start() 17 # t2 = threading.Thread(target=run,args=(2,)) 18 # t2.start() 19 print(threading.current_thread()) 20 time.sleep(1.5) 21 22 print(threading.active_count())
2.线程lock.py
1 import threading 2 import time 3 def run(n): 4 global num 5 l.acquire()#获取锁 6 num = num + 1 7 time.sleep(1) 8 l.release()#释放锁 9 print(num) 10 # print("thread",n) 11 def run2(): 12 count = 0 13 while num < 9: 14 print('---', count) 15 count +=1 16 17 l = threading.Lock() #定义锁 18 19 num = 0 20 t_list = [] 21 for i in range(10): 22 t = threading.Thread(target=run, args=(i,)) 23 t.start() 24 t_list.append(t) 25 t2 = threading.Thread(target=run2) 26 t2.start() 27 28 for t in t_list: 29 t.join() 30 31 print('----main Thread----') 32 print(num)
3.线程等待
1 import threading 2 import time 3 def run(n): 4 time.sleep(1) 5 print("thread",n) 6 7 t_list = [] 8 9 for i in range(10): 10 t = threading.Thread(target=run, args=(i,)) 11 t.start() 12 t_list.append(t) 13 # t.join() 14 for t in t_list: 15 t.join() 16 17 print('----main Thread----')
生产者消费者的两个主要作用
1.程序的解耦合，异步
2.提高了程序的运行效率
1 import threading 2 import queue 3 import time 4 def consumer(name): 5 6 while True: 7 print("%s 取到骨头[%s]吃了" %(name,q.get())) 8 time.sleep(0.5) 9 q.task_done() 10 def producer(name): 11 count = 0 12 # while q.qsize() < 5: 13 for i in range(10): 14 print("%s生成了骨头"%name,count) 15 q.put(count) 16 count +=1 17 time.sleep(0.3) 18 q.join() 19 print("------chiwan--------") 20 q = queue.Queue(maxsize = 4) 21 22 p = threading.Thread(target=producer,args=('alex',)) 23 # p2 = threading.Thread(target=producer,args=('aaa',)) 24 c = threading.Thread(target=consumer,args=('qqq',)) 25 p.start() 26 # p2.start() 27 c.start()
