Dash[diskcache]

Dash Python
1

This is installed but still I am getting this error:

dash.exceptions.MissingLongCallbackManagerError: Running long callbacks requires a manager to be installed.
Available managers:

  • Diskcache (pip install dash[diskcache]) to run callbacks in a separate Process and store results on the local filesystem.
  • Celery (pip install dash[celery]) to run callbacks in a celery worker and store results on redis.
2

What does your import and initialization of the app look like?

3 
from datetime import datetime as dt
import time
import os
import dash
import dash_bootstrap_components as dbc
from dash import html, dcc, DiskcacheManager, CeleryManager, callback
from dash.dependencies import Input, Output, State
import plotly.graph_objects as go
import plotly.express as px
import yfinance as yf


if 'REDIS_URL' in os.environ:
    # Use Redis & Celery if REDIS_URL set as an env variable
    from celery import Celery
    celery_app = Celery(__name__, broker=os.environ['REDIS_URL'], backend=os.environ['REDIS_URL'])
    background_callback_manager = CeleryManager(celery_app)

else:
    # Diskcache for non-production apps when developing locally
    import diskcache
    cache = diskcache.Cache("./cache")
    background_callback_manager = DiskcacheManager(cache)
4

For me, I needed to add this to the app initializing:

app = dash.Dash(__name__, background_callback_manager=background_callback_manager)
1 Like
5

aha, great, i have a multiple page app, when I added these line to to the app.py it worked, thank you

1 Like
6

Hi! This is likely a “duh!” question, but: Where is dash[diskcache] stored? I cannot find it in pypi. I cannot seem to find it in github either. Thanks!

ImportError: DiskcacheLongCallbackManager requires extra dependencies which can be installed doing

    $ pip install "dash[diskcache]"

Alternatively, can these “extra dependencies” be installed manually?

EDIT: This was indeed a “duh!” question. The extra dependencies can be found here:

https://github.com/plotly/dash/blob/dev/requires-diskcache.txt

They are: multiprocess, diskcache and psutil. Installing them mannualy solves the issue.

Thanks!

1 Like