Discussion on best practices for advanced caching - please join

Panel
2

I have been trying out DiskCache. It is very, very promising. As I can get the cache is working between sessions and on (--dev) restarts. It also support a lot of advanced caching strategies like expiration.

And it’s simple to use. And it could be even simpler if I could get the @cache.memoize annotation to work. See memoize not working in Panel.

Video

diskcache2

Code

import time

import numpy as np
import pandas as pd
import panel as pn
import param
from diskcache import FanoutCache

pn.config.sizing_mode = "stretch_width"

EXPIRE = 5 * 60  # 5 minutes
CACHE_DIRECTORY = "cache"

cache = FanoutCache(directory=CACHE_DIRECTORY)
# pn.state.cache["cache"]=cache # Maybe I should cache the cache or something?

# restart

def _get_data(value):
    value_str = str(value)
    if value_str in cache:
        return cache[value_str]
    else:
        print("loading data", value)
        time.sleep(1)

        df = pd.DataFrame(np.random.randint(0, 100, size=(100, 4)), columns=list("ABCD"))
        cache[value_str] = df
        print("data loaded")
        return df


class MyApp(param.Parameterized):
    value = param.Integer(default=0, bounds=(0, 10))
    data = param.Integer()
    clear_cache = param.Action()

    def __init__(self, **params):
        super().__init__(**params)

        self.data_panel = pn.pane.Str()
        self.loading_spinner = pn.widgets.indicators.LoadingSpinner(
            width=25, height=25, sizing_mode="fixed"
        )
        self.clear_cache = self._clear_cache

        self.view = pn.Column(
            self.loading_spinner,
            self.param.value,
            self.data_panel,
            self.param.clear_cache,
            max_width=500,
        )

        self._update_data()

    @param.depends("value", watch=True)
    def _update_data(self):
        self.loading_spinner.value = True
        self.data_panel.object = f"Data: {_get_data(self.value)}"
        self.loading_spinner.value = False

    def _clear_cache(self, *events):
        cache.clear()


if __name__.startswith("bokeh"):
    MyApp().view.servable()
```
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