Python 中的竞争条件

counter = 0def increment():    global counter    for _ in range(1000):        counter += 1  # 非线程安全操作thread1 = threading.Thread(target=increment)thread2 = threading.Thread(target=increment)thread1.start()thread2.start()thread1.join()thread2.join()print(counter)  # 结果可能小于2000，不可预测

import threadingcounter = 0lock = threading.Lock()def increment():    global counter    for _ in range(1000):        with lock:  # 保证一次只有一个线程进入该代码块            counter += 1thread1 = threading.Thread(target=increment)thread2 = threading.Thread(target=increment)thread1.start()thread2.start()thread1.join()thread2.join()print(counter)  # 结果始终为2000