Schedule streamlit app re-run on external event

Using Streamlit
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Schedule streamlit app re-run on external event

I have developed a streamlit app that displays outputs of CrewAI agents, tasks and tools. CrewAI runs in a separate thread and I use a queue to pass messages from CrewAI to Streamlit (using agent and task callbacks in CrewAI). In the streamlit app I’m attempting to consume the messages from the above mentioned queue.

However, in order to show a new message in the queue in streamlit, I need to trigger a rerun / refresh. The only working way of achieving this so far was to modify the streamlit python source file upon insertion of a new message from the CrewAI thread. This indeed triggers a rerun, but first of all it sometimes interrupts a running streamlit executing, and I also very often get import errors for other modules in the application.

As already mentioned, I have done some research and tried using other approaches to trigger a rerun, to no avail :frowning:

The ideal solution I’m looking for is to schedule a Streamlit app rerun, but without stopping the current run (as st.rerun() does). I would really appreciate if someone could help me with this.

1 Like
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Hi @Vitali,

Thanks for the question. Have you tried using the st.experimental_fragment decorator on a function to run it independently of the entire app. It will give you a chance to rerun only a portion of the app and not the entire page. Maybe use to to rerun the function that receives messages from the callback?

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Hi @tonykip,

thanks for your help! I had indeed read about this possibility, but forgot to check it.

I have implemented your proposal and created a function that looks for new messages in the queue from the CrewAI thread, set it to run every second and to call st.rerun() when new messages have arrived.

Thanks for you help and your quick response!

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