Where data is cached?

Using Streamlit
1

I am trying to move a small Excel macro app to a new app using streamlit, here is what I have done so far
https://xerviewer.herokuapp.com/ , First I have to say what you guys have build is amazing, I am not a dev and managed to make a web app :slight_smile:
the app just read an xer file (it is just a csv file with a lot of tables) and parse it and loaded it to an in memory sqlite DB, I am using st.cache too, the app is hosted in heroku.

my question is : is the data deleted or save it in the server, ideally I want people to use it and feel confident that I can’t read there data ?

thanks

2

Hi @mim,

By default the cache is stored in memory until the server process is killed. There are some flags you can use to alter this behavior.

    persist : boolean
        Whether to persist the cache on disk.

    max_entries : int or None
        The maximum number of entries to keep in the cache, or None
        for an unbounded cache. (When a new entry is added to a full cache,
        the oldest cached entry will be removed.) The default is None.

    ttl : float or None
        The maximum number of seconds to keep an entry in the cache, or
        None if cache entries should not expire. The default is None.
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3

I’m developping a Streamlit app in a JupyterLab environment. Only my HOME is mounted into an on-demand pod/container. If I set persist=True, what is the specific path where the cache will be stored?

4

Hi @StefanBrand,

Here’s the code that writes the cached files to disk streamlit/caching.py at d00429604bbc319bc44f3a326f8613607310978d · streamlit/streamlit · GitHub

It writes the cached .pickle file to ~/.streamlit/cache/. If the path to HOME is /home/, you can find the file in /home/.streamlit/cache/.

Does that help?

Happy Streamlit-ing! :balloon:
Snehan

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5

Does this also apply to st.memo? I’m using persist="disk", but when I do streamlit cache clear I get

Nothing to clear at /home/jovyan/.streamlit/cache.

Also pressing “C” inside the app does not clear the cache.

Edit: Cache was gone after killing the Streamlit server. Not sure exactly, which action triggered the cache clearing.

Edit2: st.experimental_memo and st.experimental_singleton do not support clearing of cache via pressing “C”: Clearing cache does not work for st.experimental_singleton and st.experimental_memo · Issue #3922 · streamlit/streamlit · GitHub

Edit3: Fixed in "Clear cache" clears memo + singleton (#3937) · streamlit/streamlit@46bff68 · GitHub

6

I’d like to better understand how caching and cached values release works. I’m hosting my app on AWS ECS. Can you explain when the memory is released? Is it only after I finish my app session?

7

Hi @snehankekre Is there a way to change the cache persist location to a custom location.?

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