Tensorboard frontend does not update when the log directory changes.

Environment information (required)

Diagnostics

--- check: autoidentify
INFO: diagnose_tensorboard.py version b5843ba83bb708385ff54baaab4b2c70c39f7a4f

--- check: general
INFO: sys.version_info: sys.version_info(major=3, minor=7, micro=4, releaselevel='final', serial=0)
INFO: os.name: posix
INFO: os.uname(): posix.uname_result(sysname='Linux', nodename='c8278555cf9a', release='4.19.69-1-MANJARO', version='#1 SMP PREEMPT Thu Aug 29 08:51:46 UTC 2019', machine='x86_64')
INFO: sys.getwindowsversion(): N/A

--- check: package_management
INFO: has conda-meta: False
INFO: $VIRTUAL_ENV: None

--- check: installed_packages
INFO: installed: tensorboard==1.14.0
diagnose_tensorboard.py:197: DeprecationWarning: The 'warn' function is deprecated, use 'warning' instead
  logging.warn("no installation among: %s", sorted(family))
WARNING: no installation among: ['tensorflow', 'tensorflow-gpu', 'tf-nightly', 'tf-nightly-2.0-preview', 'tf-nightly-gpu', 'tf-nightly-gpu-2.0-preview']
WARNING: no installation among: ['tensorflow-estimator', 'tensorflow-estimator-2.0-preview', 'tf-estimator-nightly']

--- check: tensorboard_python_version
INFO: tensorboard.version.VERSION: '1.14.0'

--- check: tensorflow_python_version
Traceback (most recent call last):
  File "diagnose_tensorboard.py", line 419, in main
    suggestions.extend(check())
  File "diagnose_tensorboard.py", line 77, in wrapper
    result = fn()
  File "diagnose_tensorboard.py", line 236, in tensorflow_python_version
    import tensorflow as tf
ModuleNotFoundError: No module named 'tensorflow'

--- check: tensorboard_binary_path
INFO: which tensorboard: b'/usr/local/bin/tensorboard\n'

--- check: readable_fqdn
INFO: socket.getfqdn(): 'c8278555cf9a'

--- check: stat_tensorboardinfo
INFO: directory: /tmp/.tensorboard-info
INFO: os.stat(...): os.stat_result(st_mode=16895, st_ino=19925017, st_dev=48, st_nlink=2, st_uid=0, st_gid=0, st_size=4096, st_atime=1569252142, st_mtime=1569252142, st_ctime=1569252142)
INFO: mode: 0o40777

--- check: source_trees_without_genfiles
INFO: tensorboard_roots (1): ['/usr/local/lib/python3.7/site-packages']; bad_roots (0): []

--- check: full_pip_freeze
INFO: pip freeze --all:
absl-py==0.8.0
grpcio==1.23.0
Markdown==3.1.1
numpy==1.17.2
pip==19.2.3
protobuf==3.9.1
setuptools==41.2.0
six==1.12.0
tensorboard==1.14.0
Werkzeug==0.16.0
wheel==0.33.6

Issue description

Please describe the bug as clearly as possible. How can we reproduce the
problem without additional resources (including external data files and
proprietary Python modules)?

I am trying to run the tensorboard server in a docker container but there seems to be problems with updating the log directory. Tensorboard will load a single file and then be stuck in that state even if I manually go into the container and delete the files. For example, I have 4 folders each with a tfevents file and this is what the resulting frontend is stuck at:

An exception is raised in the Reloader thread during spin up of the server which seems related to the issue. Output of docker run:

/usr/local/lib/python3.7/site-packages/tensorboard/compat/tensorflow_stub/dtypes.py:541: FutureWarning: Passing (type, 1) or '1type' as a synonym of type is deprecated; in a future version of numpy, it will be understood as (type, (1,)) / '(1,)type'.
  _np_qint8 = np.dtype([("qint8", np.int8, 1)])
/usr/local/lib/python3.7/site-packages/tensorboard/compat/tensorflow_stub/dtypes.py:542: FutureWarning: Passing (type, 1) or '1type' as a synonym of type is deprecated; in a future version of numpy, it will be understood as (type, (1,)) / '(1,)type'.
  _np_quint8 = np.dtype([("quint8", np.uint8, 1)])
/usr/local/lib/python3.7/site-packages/tensorboard/compat/tensorflow_stub/dtypes.py:543: FutureWarning: Passing (type, 1) or '1type' as a synonym of type is deprecated; in a future version of numpy, it will be understood as (type, (1,)) / '(1,)type'.
  _np_qint16 = np.dtype([("qint16", np.int16, 1)])
/usr/local/lib/python3.7/site-packages/tensorboard/compat/tensorflow_stub/dtypes.py:544: FutureWarning: Passing (type, 1) or '1type' as a synonym of type is deprecated; in a future version of numpy, it will be understood as (type, (1,)) / '(1,)type'.
  _np_quint16 = np.dtype([("quint16", np.uint16, 1)])
/usr/local/lib/python3.7/site-packages/tensorboard/compat/tensorflow_stub/dtypes.py:545: FutureWarning: Passing (type, 1) or '1type' as a synonym of type is deprecated; in a future version of numpy, it will be understood as (type, (1,)) / '(1,)type'.
  _np_qint32 = np.dtype([("qint32", np.int32, 1)])
/usr/local/lib/python3.7/site-packages/tensorboard/compat/tensorflow_stub/dtypes.py:550: FutureWarning: Passing (type, 1) or '1type' as a synonym of type is deprecated; in a future version of numpy, it will be understood as (type, (1,)) / '(1,)type'.
  np_resource = np.dtype([("resource", np.ubyte, 1)])
TensorFlow installation not found - running with reduced feature set.
Exception in thread Reloader:
Traceback (most recent call last):
  File "/usr/local/lib/python3.7/threading.py", line 926, in _bootstrap_inner
    self.run()
  File "/usr/local/lib/python3.7/threading.py", line 870, in run
    self._target(*self._args, **self._kwargs)
  File "/usr/local/lib/python3.7/site-packages/tensorboard/backend/application.py", line 430, in _reload
    multiplexer.Reload()
  File "/usr/local/lib/python3.7/site-packages/tensorboard/backend/event_processing/plugin_event_multiplexer.py", line 240, in Reload
    Worker()
  File "/usr/local/lib/python3.7/site-packages/tensorboard/backend/event_processing/plugin_event_multiplexer.py", line 218, in Worker
    accumulator.Reload()
  File "/usr/local/lib/python3.7/site-packages/tensorboard/backend/event_processing/plugin_event_accumulator.py", line 177, in Reload
    for event in self._generator.Load():
  File "/usr/local/lib/python3.7/site-packages/tensorboard/backend/event_processing/directory_watcher.py", line 89, in Load
    for event in self._LoadInternal():
  File "/usr/local/lib/python3.7/site-packages/tensorboard/backend/event_processing/directory_watcher.py", line 113, in _LoadInternal
    for event in self._loader.Load():
  File "/usr/local/lib/python3.7/site-packages/tensorboard/backend/event_processing/event_file_loader.py", line 95, in Load
    yield event_pb2.Event.FromString(record)
google.protobuf.message.DecodeError: Error parsing message

TensorBoard 1.14.0 at http://c8278555cf9a:6006/ (Press CTRL+C to quit)

If i use the official tensorflow image everything works fine. However, the problem with that solution is that the image is too big at 1.2 gigs. I really just need a barebones tensorboard.

Steps to reproduce:

1. Use this Dockerfile:

FROM python:3.7-slim

RUN pip install --upgrade pip
RUN pip install tensorboard==1.14

COPY diagnose_tensorboard.py .

VOLUME /logs

EXPOSE 6006

ENTRYPOINT tensorboard --logdir /logs

2. Build the image:
   docker build -t my-tb .

3. Run a container with mounted tfevent files:
   docker run -it --rm -p 6006:6006 --name tb_test -v $(realpath tb_files):/logs my-tb /bin/bash -c "tensorboard --logdir /logs"

4. Go to localhost:6006

5. Observe issue. Try deleting tfevent files in the container and notice that the frontend never updates.