Background callback returns 502

Dash Python
1

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Describe your context
I have some high CPU/RAM efficient workflow that handling by celery and in the same time I have background callback that triggering this workflow and partially doing some CPU-related calculations too.

  • replace the result of pip list | grep dash below
│ dash                 │ 2.7.0       │                                            │
│ dash-dv2             │ 1.0.95      │                                            │
│ fef-dash             │ 4.4.4       │                                            │
│ dash-table           │ 5.0.0       │                                            │
│ dash-core-components │ 2.0.0       │                                            │
│ dash-html-components │ 2.0.0       │                                            │
  • if frontend related, tell us your Browser, Version and OS
    • OS: macOS
    • Browser Chrome
    • Version 108

Describe the bug

When I’m starting only one this loading in parallel – all is ok, when more than three (including) – I’m receiving 502 error:
The issue reproducing regularly, not one-time issue and not fixing by restarting containers (we’re using k8s: 2 pods of dash app, 2 Redis instances, 2 scalable pods of nginx-ingress).

HTTP/1.1 502 Bad Gateway
Date: Thu, 29 Dec 2022 03:15:18 GMT
Content-Type: text/html
Content-Length: 552
Connection: keep-alive
Content-Security-Policy: <HIDDEN>
Referrer-Policy: no-referrer
Strict-Transport-Security: max-age=31536000; includeSubDomains; preload
X-Content-Type-Options: nosniff
X-Frame-Options: SAMEORIGIN
X-XSS-Protection: 1; mode=block

Expected behavior

Not receiving 502 or with described output.

Screenshots

image

2

Hmm, how is your load balancer working?

What does it say for the routing of these, are they going to the same backend?