说明：这个问题，困惑了好久，在网上查了很久，一直没能解决，直到我在stackoverflow上看到有一位博主的回答
链接在这里：(https://stackoverflow.com/questions/47113472/tensorboard-error-no-dashboards-are-active-for-current-data-set)
our issue may be related to the drive you are attempting to start tensorboard from and the drive your logdir is on. Tensorboard uses a colon to separate the optional run name and the path in the logdir flag, so your path is being interpreted as \path\to\output\folder with name C. This can be worked around by either starting tensorboard from the same drive as your log directory or by providing an explicit run name, e.g. --logdir=mylogs:C:\path\to\output\folder.
什么意思呢？也就是说你的--logdir后面的文件和目录是通过冒号分割的，先写文件，再写路径：
附上我的代码：
import tensorflow as tf
a=tf.constant(1,name="input_a")
b=tf.constant(2,name="input_b")
c=tf.multiply(a,b, name='mul_c')
d=tf.multiply(a,b, name='mul_d')
e=tf.add(c,d, name='add_e')
print(e)
sess=tf.Session()
sess.run(e)
writer=tf.summary.FileWriter('./my_graph',sess.graph)
然后在console上执行：
注意：tensorboard --logdir=file_name:path_name
tensorboard --logdir=my_graph:C:/Document/PY/tensorflow
W0618 12:28:00.452951 Reloader tf_logging.py:121] Found more than one graph event per run, or there was a metagraph containing a graph_def, as well as one or more graph events. Overwriting the graph with the newest event.
W0618 12:28:00.453946 Reloader tf_logging.py:121] Found more than one metagraph event per run. Overwriting the metagraph with the newest event.
TensorBoard 1.8.0 at http://LYUJIUJIN:6006 (Press CTRL+C to quit)
