trame/synchronization_context/get_cached_data_array key not found after on_client_connected callback

[callaway-chris-yang]

Issue solved

I used

ctrl.on_client_connected.add(on_client_connected)

but should be

ctrl.on_client_connected.add_task(on_client_connected)

for async functions.

Then, I used both to enable 'remote rendering', but should be only use one of them.

pv.set_jupyter_backend('server')
view = plotter_ui(self.plotter, mode="server")

after test, I found out only this worked for me.

view = plotter_ui(self.plotter, mode="server")

Really appreciate the help and time from jourdain

---

Hi guys,

Could anyone give me some suggestions on this error code?

Here is the code I am using to refresh the plot.

def on_client_connected():

    check the database to determine if the plot needs to be refreshed with the new data

    if yes:
        plotter.clear()
        plotter.add_mesh()
        plotter.reset_camera()
        ctrl.view_update()
        state.flush() # 

ctrl.on_client_connected.add(on_client_connected)

Here is the error code from terminal

Traceback (most recent call last):
File "/workspaces/pyvista-post-fea/.venv/lib/python3.12/site-packages/wslink/protocol.py", line 313, in onCompleteMessage
results = func(*args, **kwargs)
^^^^^^^^^^^^^^^^^^^^^
File "/workspaces/pyvista-post-fea/.venv/lib/python3.12/site-packages/trame_vtk/modules/vtk/protocols/local_rendering.py", line 33, in get_array
self.context.get_cached_data_array(data_hash, binary)
File "/workspaces/pyvista-post-fea/.venv/lib/python3.12/site-packages/trame_vtk/modules/vtk/serializers/synchronization_context.py", line 35, in get_cached_data_array
cache_obj = self.data_array_cache[p_md5]
~~~~~~~~~~~~~~~~~~~~~^^^^^^^
KeyError: '71eb8edfba8d622d70d519d95e525d4c_105046d'

As I mentioned above, the error comes out when the plot gets refreshed.

The tricky thing is this error does not affect the frontend rendering.

I feel like the code was trying to read some expired data, like backend and frontend are not sync.

Tried to add some time.sleep() to give the server to load the data. But didnt help.

Please give me some suggestions.

Thanks you guys.

[jourdain]

What you are describing is indeed correct and reflect what is happening.

You should be able to fix that by doing the following

async def on_client_connected():
    await asyncio.sleep(1)
    if yes:
        with state:
           plotter.clear()
           plotter.add_mesh()
           plotter.reset_camera()
           ctrl.view_update()

ctrl.on_client_connected.add_task(on_client_connected)

[callaway-chris-yang]

Thank you so much for the time helping me on this. I would also do some tests and keep you posted if I find anything.

What is the trame-vtklocal? Will this new version fix the issue?

[jourdain]

trame-vtklocal use VTK/WASM for doing the rendering and is going to be the successor of the current local rendering option of trame-vtk.

[callaway-chris-yang]

Got it. forgot to mention, I used 'remote' rendering because I added multiple widgets. Not sure if that could be part of the root cause.

[jourdain]

Then you should not have any error if you use VtkRemoteView.

[callaway-chris-yang]

I am using pyvista and trame. Should I switch to VtkRemoteView?

pv.OFF_SCREEN = True
pv.set_jupyter_backend('trame') 
plotter = pv.Plotter(off_screen=True)
view = plotter_ui(self.plotter, default_server_rendering=True)
ctrl.view_update = view.update

[jourdain]

pv.set_jupyter_backend('server') # one or the other
view = plotter_ui(self.plotter, mode="server")# one or the other

[callaway-chris-yang]

Thank you so much for the suggestions. I have some updates.

Using

pv.set_jupyter_backend('server')

will have the sync error.

But,

view = plotter_ui(self.plotter, mode="server")

works fine.