进程简单了解和使用

1. 进程
        - 进程间数据不共享
            data_list = []
            def task(arg):
                data_list.append(arg)
                print(data_list)


            def run():
                for i in range(10):
                    p = multiprocessing.Process(target=task,args=(i,))
                    # p = threading.Thread(target=task,args=(i,))
                    p.start()

            if __name__ == '__main__':
                run()
        - 常用功能: 
            - join
            - deamon
            - name
            - multiprocessing.current_process()
            - multiprocessing.current_process().ident/pid
        
        - 类继承方式创建进程
            class MyProcess(multiprocessing.Process):

                def run(self):
                    print('当前进程',multiprocessing.current_process())


                def run():
                    p1 = MyProcess()
                    p1.start()

                    p2 = MyProcess()
                    p2.start()

            if __name__ == '__main__':
                run()
                
    2. 进程间数据共享
        Queue:
            linux:
                q = multiprocessing.Queue()

                def task(arg,q):
                    q.put(arg)

                def run():
                    for i in range(10):
                        p = multiprocessing.Process(target=task, args=(i, q,))
                        p.start()

                    while True:
                        v = q.get()
                        print(v)

                run()
            windows:    
                def task(arg,q):
                    q.put(arg)

                if __name__ == '__main__':
                    q = multiprocessing.Queue()
                    for i in range(10):
                        p = multiprocessing.Process(target=task,args=(i,q,))
                        p.start()
                    while True:
                        v = q.get()
                        print(v)
    
        Manager:（*）
            Linux:
                m = multiprocessing.Manager()
                dic = m.dict()

                def task(arg):
                    dic[arg] = 100

                def run():
                    for i in range(10):
                        p = multiprocessing.Process(target=task, args=(i,))
                        p.start()

                    input('>>>')
                    print(dic.values())
                    
                if __name__ == '__main__':
                    
                    run()
            windows:
                def task(arg,dic):
                    time.sleep(2)
                    dic[arg] = 100

                if __name__ == '__main__':
                    m = multiprocessing.Manager()
                    dic = m.dict()

                    process_list = []
                    for i in range(10):
                        p = multiprocessing.Process(target=task, args=(i,dic,))
                        p.start()

                        process_list.append(p)

                    while True:
                        count = 0
                        for p in process_list:
                            if not p.is_alive():
                                count += 1
                        if count == len(process_list):
                            break
                    print(dic)
    
    3. 进程锁 
            import time
            import threading
            import multiprocessing


            lock = multiprocessing.RLock()

            def task(arg):
                print('鬼子来了')
                lock.acquire()
                time.sleep(2)
                print(arg)
                lock.release()

            if __name__ == '__main__':
                p1 = multiprocessing.Process(target=task,args=(1,))
                p1.start()

                p2 = multiprocessing.Process(target=task, args=(2,))
                p2.start()
    
        为什么要加锁？
    
    4. 进程池
        import time
        from concurrent.futures import ThreadPoolExecutor,ProcessPoolExecutor

        def task(arg):
            time.sleep(2)
            print(arg)

        if __name__ == '__main__':

            pool = ProcessPoolExecutor(5)
            for i in range(10):
                pool.submit(task,i)