[hotfixes] Configure task behavior to acknowledge after execution to trigger requeuing when interrupted

[bjester]

Summary

Testing on hotfixes separately

Description of the change(s) you made

• Adds celery task options that will cause interrupted tasks to be requeued
• Adds celery app method for querying what's in the queue
• Removes flags added in Disable mingle and gossip when running workers. #1519

Manual verification steps performed

1. Step 1
2. Step 2
3. ...

Logging snapshots

When a worker is forcibly interrupted, it should restore (unacknowledged) tasks to the queue:

[2021-09-23 16:22:57,214: INFO/MainProcess] Connected to redis://localhost:6379/0
[2021-09-23 16:22:57,223: INFO/MainProcess] celery@phlack ready.
[2021-09-23 16:22:57,233: INFO/MainProcess] Received task: calculate_user_storage_task[69d10852-22ea-48a0-809d-d97ade8a2218]  ETA:[2021-09-23 14:32:37.734031-07:53] 
[2021-09-23 16:23:16,978: INFO/MainProcess] Received task: export_channel_task[1789ac915aca4519bf04a8c7755f5efc]  
^C
worker: Hitting Ctrl+C again will terminate all running tasks!

worker: Warm shutdown (MainProcess)
^C
worker: Cold shutdown (MainProcess)
[2021-09-23 17:12:01,685: WARNING/MainProcess] Restoring 2 unacknowledged message(s)

Does this introduce any tech-debt items?

---

Reviewer guidance

How can a reviewer test these changes?

1. Add a time.sleep(10000) to a task such as the publish task
2. Initiate publishing of a channel
3. Start the celery workers
4. Observe the workers should start the task
5. Send signal to terminate workers twice: Ctrl+C
6. Observe during worker shutdown you should see a message like Restoring 1 unacknowledged message(s); other incomplete scheduled tasks should be included such as tasks with an ETA
7. Start the celery workers again
8. Observe celery should restart the publishing task

Are there any risky areas that deserve extra testing?

References

https://docs.celeryproject.org/en/v4.4.7/userguide/configuration.html#std:setting-task_acks_late
https://docs.celeryproject.org/en/v4.4.7/faq.html#faq-acks-late-vs-retry
Querying celery queue directly: redis-cli LRANGE celery 0 -1

Comments

---

Contributor's Checklist

PR process:

• If this is an important user-facing change, PR or related issue the CHANGELOG label been added to this PR. Note: items with this label will be added to the CHANGELOG at a later time
• If this includes an internal dependency change, a link to the diff is provided
• The docs label has been added if this introduces a change that needs to be updated in the user docs?
• If any Python requirements have changed, the updated requirements.txt files also included in this PR
• Opportunities for using Google Analytics here are noted
• Migrations are safe for a large db

Studio-specifc:

• All user-facing strings are translated properly
• The notranslate class been added to elements that shouldn't be translated by Google Chrome's automatic translation feature (e.g. icons, user-generated text)
• All UI components are LTR and RTL compliant
• Views are organized into pages, components, and layouts directories as described in the docs
• Users' storage used is recalculated properly on any changes to main tree files
• If there new ways this uses user data that needs to be factored into our Privacy Policy, it has been noted.

Testing:

• Code is clean and well-commented
• Contributor has fully tested the PR manually
• If there are any front-end changes, before/after screenshots are included
• Critical user journeys are covered by Gherkin stories
• Any new interactions have been added to the QA Sheet
• Critical and brittle code paths are covered by unit tests

---

Reviewer's Checklist

This section is for reviewers to fill out.

• Automated test coverage is satisfactory
• PR is fully functional
• PR has been tested for accessibility regressions
• External dependency files were updated if necessary (yarn and pip)
• Documentation is updated
• Contributor is in AUTHORS.md

[sonarqubecloud]

SonarCloud Quality Gate failed.   

96 Bugs
0 Vulnerabilities
6 Security Hotspots
57 Code Smells

No Coverage information
5.3% Duplication

[rtibbles]

Works as described in local testing.