No Ray logs generated

Hi guys!

I would like to check some system level loggings by view loggings in Ray log directory, as described here . By main function is quite simple

    import ray
    train_wrapper(args,num_workers=args.num_workers, use_gpu=True)

I first did not set vairable _temp_dir. And later I set it to a directory which has my authentication. But by either setting, there is no session_*/logs directory generated as described.

I wonder do I miss some important configuration to use Ray logs or maybe I came up with some bug?