求助：tflearn中try/except加载预训练模型失败后训练报会话已关闭错误

开发场景说明 #

• 开发身份：编程初学者
• 运行环境：配置了tflearn库的Anaconda虚拟环境，开发目标为搭建AI聊天机器人
• 代码设计目标：通过try/except逻辑实现模型加载流程自动适配：优先读取本地已存储的预训练模型model.tflearn，若模型文件不存在则自动启动模型训练流程，训练完成后将模型持久化保存，避免重复训练占用资源
• 核心逻辑代码片段：

  try:
      model.load("model.tflearn")
  except:
      model.fit(training, output, n_epoch=300, batch_size=8, show_metric=True)
      model.save("model.tflearn")
  

异常表现说明 #

• 异常触发条件：本地不存在可正常加载的model.tflearn预训练模型文件时，程序运行中断抛出错误
• 无异常对照场景：
  • 本地存在完整、可正常加载的预训练模型文件时，程序可走完所有流程正常运行
  • 移除try/except异常捕获逻辑，每次运行直接执行模型训练流程时，程序可正常运行完成训练与保存
• 完整报错栈信息：

  程序最终抛出的核心错误为RuntimeError: Attempted to use a closed Session.，完整栈跟踪内容如下：

  Traceback (most recent call last):
    File "C:/Users/Eric/PycharmProjects/ai_chatbot/nlp.py", line 82, in <module>
      model.fit(training, output, n_epoch=300, batch_size=8, show_metric=True)
    File "C:\Users\Eric\anaconda3\envs\chatbot\lib\site-packages\tflearn\models\dnn.py", line 206, in fit
      callbacks=callbacks)
    File "C:\Users\Eric\anaconda3\envs\chatbot\lib\site-packages\tflearn\helpers\trainer.py", line 344, in fit
      show_metric)
    File "C:\Users\Eric\anaconda3\envs\chatbot\lib\site-packages\tflearn\helpers\trainer.py", line 826, in _train
      tflearn.is_training(True, session=self.session)
    File "C:\Users\Eric\anaconda3\envs\chatbot\lib\site-packages\tflearn\config.py", line 95, in is_training
      tf.get_collection('is_training_ops')[0].eval(session=session)
    File "C:\Users\Eric\anaconda3\envs\chatbot\lib\site-packages\tensorflow\python\framework\ops.py", line 921, in eval
      return _eval_using_default_session(self, feed_dict, self.graph, session)
    File "C:\Users\Eric\anaconda3\envs\chatbot\lib\site-packages\tensorflow\python\framework\ops.py", line 5512, in _eval_using_default_session
      return session.run(tensors, feed_dict)
    File "C:\Users\Eric\anaconda3\envs\chatbot\lib\site-packages\tensorflow\python\client\session.py", line 968, in run
      run_metadata_ptr)
    File "C:\Users\Eric\anaconda3\envs\chatbot\lib\site-packages\tensorflow\python\client\session.py", line 1114, in _run
      raise RuntimeError('Attempted to use a closed Session.')
  RuntimeError: Attempted to use a closed Session.
  

内容的提问来源于stack exchange，提问作者Eric