# 介绍

Timeline类可以被用于以Chrome Tracing的格式生成一个JSON trace文件:

# 3.另一点问题

thank you for your explanations. The reason why I thought that this information could be there, is because when I generate a timeline in the Chrome trace format and load it in the browsers, for some of the tensors I can see a span in it (see a screenshot below). I tried to understand what this span means and made a wrong hypothesis that it may correspond to the period when the tensor was kept in memory. But from what you are saying it does not seem to be the case. That said, I am still curious: what do the spans in the timeline stand for, why do some tensors have a span associated with them, while other just a creation moment?

show_memory模式下，有些tensors可以看到一个span，是否对应该tensor在memory中的period？那么这些在timeline中的spans代表了啥？为什么一些tensors有一个span，而另一些只有一个创建点？

prb12的解答：

NodeExecStats proto实际上没有提供足够的信息来准确跟踪tensor的依赖。为了这样做，你实际需要知道完整的执行数据流图(dataflow graph)——这与input GraphDef并不相同，因为placer和optimizer可以做出更实际的变更。

# 4.show_dataflow=True

generate_chrome_trace_format(self, show_dataflow=True, show_memory=False)


# 5.

1.在未来的一段时间内，不可能有很多时间去写一篇关于timeline和tracing的tutorial

2.chrome:tracing上对应的pid不是真实pid，只是为了

3.tracing机制的设计是为了捕获单个step.