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LernerLab / GuPPy

Guided Photometry Analysis in Python, a free and open-source FP analysis tool.
GNU General Public License v3.0
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'TKAgg' backend error on headless server #52

Open vncntprvst opened 11 months ago

vncntprvst commented 11 months ago

When starting the GuPPy User Interface from a server running in 'headless' mode, there's an issue with 'TKAgg' backend. The full error stack looks like this:

panel serve --show GuPPy/savingInputParameters.ipynb

2023-09-07 16:44:46,478 Starting Bokeh server version 2.3.2 (running on Tornado 6.1)
2023-09-07 16:44:46,479 User authentication hooks NOT provided (default user enabled)
2023-09-07 16:44:46,482 Bokeh app running at: http://localhost:5006/savingInputParameters
2023-09-07 16:44:46,482 Starting Bokeh server with process id: 96012
2023-09-07 16:44:47,365 Error running application handler <bokeh.application.handlers.notebook.NotebookHandler object at 0x7ff0e76917b8>: Cannot load backend 'TKAgg' which requires the 'tk' interactive framework, as 'headless' is currently running
File "pyplot.py", line 287, in switch_backend:
newbackend, required_framework, current_framework)) Traceback (most recent call last):
  File "/home/wanglab/mambaforge/envs/guppy/lib/python3.6/site-packages/bokeh/application/handlers/code_runner.py", line 197, in run
    exec(self._code, module.__dict__)
  File "/home/wanglab/code/FP/GuPPy/GuPPy/savingInputParameters.ipynb", line 16, in <module>
    "import numpy as np\n",
  File "/home/wanglab/code/FP/GuPPy/GuPPy/preprocess.py", line 16, in <module>
    plt.switch_backend('TKAgg')
  File "/home/wanglab/mambaforge/envs/guppy/lib/python3.6/site-packages/matplotlib/pyplot.py", line 287, in switch_backend
    newbackend, required_framework, current_framework))
ImportError: Cannot load backend 'TKAgg' which requires the 'tk' interactive framework, as 'headless' is currently running

This issue can be resolved with using a virtual display server, such as:

sudo apt-get install xvfb
xvfb-run -a panel serve --show GuPPy/savingInputParameters.ipynb

Then the server runs fine (if using VS Code, it takes care of the required port forwarding).

2023-09-07 16:49:06,688 Starting Bokeh server version 2.3.2 (running on Tornado 6.1)
2023-09-07 16:49:06,689 User authentication hooks NOT provided (default user enabled)
2023-09-07 16:49:06,693 Bokeh app running at: http://localhost:5006/savingInputParameters
2023-09-07 16:49:06,693 Starting Bokeh server with process id: 97214
Launching server at http://localhost:44699

There may be other way to solve this. This one works for Linux servers / workstations at least.

venus-sherathiya commented 11 months ago

Thank you for the solution !! I really appreciate it.