[🐛 BUG] State variable overload freezes the app

[studentdotai]

What went wrong? 🤔

I have been encountering following problem (Taipy 4.0.2)
This issue freezes all activity and no further interactions are possible.

Only solution found is to refresh webpage (95% success), but all states will be reset. This is not acceptable in long machine learning preprocessing pipelines.

G:\Python Projects\GIS\RouteAssistant\.venv\Lib\site-packages\taipy\gui\gui.py:700: TaipyGuiWarning:

A problem occurred while resolving variable 'data_tab_select_TPMDL_2' in module '__main__'.

The variable can be different, as well as gui elements ( selector (with input), Toggle(multi string select), buttons_(on_action_call) )
It is totally inconsistent and can occur on first action, or after some time.
As well, i have multi page app, where main is in totally different .py file.
For GUI , .tgb is used with function based pages with tgb.Page() as data_page:

Expected Behavior

Just state.variable change or function execution (on_action) is needed.

Steps to Reproduce Issue

Taipy issue 1.md

WorldPortIndex_2019.csv

World Port Index_2019Shapefile.zip

This is cut-down version of the app with a reproducible error.

[2025-01-29 18:27:33.959][Taipy][INFO]  * Server reloaded on http://127.0.0.1:5000
G:\Python Projects\GIS\RouteAssistant\.venv\Lib\site-packages\taipy\gui\data\data_scope.py:52: TaipyGuiWarning:

Session id 20250111215105866541-0.14820851830190673 not found in data scope. Taipy will automatically create a scope for this session id but you may have to reload your page.

G:\Python Projects\GIS\RouteAssistant\.venv\Lib\site-packages\taipy\gui\gui.py:700: TaipyGuiWarning:

A problem occurred while resolving variable 'arr_port_name_TPMDL_2' in module '__main__'.

G:\Python Projects\GIS\RouteAssistant\.venv\Lib\site-packages\taipy\gui\gui.py:700: TaipyGuiWarning:

A problem occurred while resolving variable 'dep_port_name_TPMDL_2' in module '__main__'.

[2025-01-29 18:27:43.289][Taipy][INFO]  * Server reloaded on http://127.0.0.1:5000
G:\Python Projects\GIS\RouteAssistant\.venv\Lib\site-packages\taipy\gui\gui.py:700: TaipyGuiWarning:

A problem occurred while resolving variable 'arr_port_name_TPMDL_2' in module '__main__'.

For error to appear, update the code (CTRL+S), and even when it looks like fully loaded in the browser, by pressing any "Callback" element this warning appears. And freezes all app. It is especcially noticable with heavier states and callbacks like Plotly figure generation from PostGIS database.

Solution Proposed

If some notification would be shown when data is loaded (Taipy "notify" at the end of callback doesn't show real picture)
Queue method that will not overload the process and lets data load in a sequence of callbacks.

Runtime Environment

Windows 11, Edge browser

Browsers

Microsoft Edge

OS

Windows

Version of Taipy

4.0.2

Additional Context

Acceptance Criteria

• A unit test reproducing the bug is added.
• Any new code is covered by a unit tested.
• Check code coverage is at least 90%.
• The bug reporter validated the fix.
• Related issue(s) in taipy-doc are created for documentation and Release Notes are updated.

Code of Conduct

• I have checked the existing issues.
• I am willing to work on this issue (optional)