posit-dev / posit-dev/py-shiny
`reactive.poll` causes busy/idle messages to be sent each time polling message runs
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- Dominant language
- Python
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Description
For example:
from shiny import App, ui, reactive
app_ui = ui.page_fluid("hello")
def server(input, output, session):
def poll_fn() -> int:
return 1
@reactive.poll(poll_fn, 0.5)
def poll_result():
print("Running poll_result")
return None
app = App(app_ui, server, debug=True)
This prints the following at the console:
SEND: {"busy": "busy"}
SEND: {"busy": "idle"}
SEND: {"values": {}, "inputMessages": [], "errors": {}}
SEND: {"busy": "busy"}
SEND: {"busy": "idle"}
SEND: {"values": {}, "inputMessages": [], "errors": {}}
SEND: {"busy": "busy"}
SEND: {"busy": "idle"}
SEND: {"values": {}, "inputMessages": [], "errors": {}}
SEND: {"busy": "busy"}
SEND: {"busy": "idle"}
SEND: {"values": {}, "inputMessages": [], "errors": {}}
...
Note that this also causes it to send {"values": {}, "inputMessages": [], "errors": {}} unnecessarily.
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First steps
- Read the whole issue, then the project's contributing guide.
- Comment on the issue to say you are picking it up — it saves two people doing the same work.
- Fork the repository and make your change on a branch.
- Open a pull request that references the issue number.
Research direction
Start with the supplied minimal Python reproduction and trace the reactive.poll polling cycle that produces the repeated busy/idle and empty update messages. Done means unchanged polling no longer sends those unnecessary messages while the polling behavior still works.
Written by the indexing model from the issue text.
Assessment
- Tech stack
- python
- Domain
- backend
- Issue type
- Bug
- Difficulty
- 3/5
- Estimated time
- 1-2 days
- Activity status
- Stale
- Clarity
- Mostly clear
- Newbie friendliness
- 38/100