[4.1.0.rc3] Error to download PDF or Image #30645

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1. dosubot commented on Oct 17, 2024

   

   dosubotBot

   on Oct 17, 2024 – with DosuBot

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   Hey @jacob-roldan! 👋 I'm here to help you with any bugs, questions, or becoming a contributor. Let's squash those bugs together!

   I found a similar open issue that might be related to the problem you're experiencing: Upon download as PDF, charts on a long dashboard render as loading image. This issue suggests that the problem might be due to the virtualization feature, which off-loads charts that are away from the viewport. A workaround is to disable the virtualization feature by updating the Superset configuration:

   1. Open the superset_config_docker.py file.

   2. Update the FEATURE_FLAGS variable as follows:

      FEATURE_FLAGS = {
          "DASHBOARD_VIRTUALIZATION": False,
      }

   This change ensures that the dashboard loads all charts at once, preventing loading spinners from appearing in the downloaded PDF or image ^[1].

   To continue talking to Dosu, mention @dosu.
2. dosubot

   added

   dashboard:exportRelated to exporting dashboardsRelated to exporting dashboards

   on Oct 17, 2024
3. jacob-roldan

   changed the title [-][4.0.1.rc3] Error to download PDF or Image[/-] [+][4.1.0.rc3] Error to download PDF or Image[/+] on Oct 17, 2024
4. sadpandajoe

   added this to Apache Superset 4.1on Oct 17, 2024
5. sadpandajoe

   moved this to New Issues in Apache Superset 4.1on Oct 17, 2024
6. sadpandajoe

   assigned

   geido

   on Oct 17, 2024
7. sadpandajoe commented on Oct 17, 2024

   

   sadpandajoe

   on Oct 17, 2024

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   @geido i can't remember if i should have spun this up with a feature flag or not.
8. sadpandajoe commented on Oct 17, 2024

   

   sadpandajoe

   on Oct 17, 2024

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   @jacob-roldan I ran this on an instance I have and it looks like I do see that message for a bit (maybe a minute or two) but eventually the dashboard does download. How long did you wait until moving away from the dashboard?

   👍React with 👍1Reacted by Geidō
9. michael-s-molina commented on Oct 17, 2024

   

   michael-s-molina

   on Oct 17, 2024

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   @sadpandajoe I can also confirm this problem using our internal test environment.

   4.0.2

   Screen.Recording.2024-10-17.at.16.25.03.mov

   4.1.0rc3

   Screen.Recording.2024-10-17.at.16.24.08.mov
10. michael-s-molina

    moved this from New Issues to Release Blockers in Apache Superset 4.1on Oct 17, 2024
11. michael-s-molina commented on Oct 17, 2024

    

    michael-s-molina

    on Oct 17, 2024

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    Is there any configuration change between 4.0.2 and 4.1.0rc3 that is needed to generate the screenshots?
12. sadpandajoe commented on Oct 18, 2024

    

    sadpandajoe

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    @michael-s-molina @jacob-roldan are there any logs? We've actually been running this code on prod for a bit and haven't gotten this issue. Trying to debug this but can't seem to repro it on our end.
13. michael-s-molina commented on Oct 18, 2024

    

    michael-s-molina

    on Oct 18, 2024

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    @sadpandajoe @geido @eschutho I was able to pinpoint the problem. The reason for the failure is because the screenshot generation on 4.1.0 RC3 caches the screenshots using the THUMBNAIL_CACHE_CONFIG which is a NullCache by default. A NullCache is a cache that does not cache anything, and that's why the frontend cannot find the screenshots and enters in a loop. The fix for this would be to make the default configuration of THUMBNAIL_CACHE_CONFIG similar to what we do with the Explore form data and save the thumbnails in the database using the SupersetMetastoreCache:

    THUMBNAIL_CACHE_CONFIG = {
        "CACHE_TYPE": "SupersetMetastoreCache",
        "CACHE_DEFAULT_TIMEOUT": // set a value
        # Should the timeout be reset when retrieving a cached value?
        "REFRESH_TIMEOUT_ON_RETRIEVAL": True,
        # The following parameter only applies to `MetastoreCache`:
        # How should entries be serialized/deserialized?
        "CODEC": // define the appropriate codec
    }
    

    Talking to @villebro about this issue, he raised a good point where previously Celery workers were not a hard requirement to install Superset but more of an optional feature. If the screenshot generation always requires Celery workers from now on, that could constitute a breaking change. Let me know your thoughts.
14. geido commented on Oct 22, 2024

    

    geido

    on Oct 22, 2024

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    @sadpandajoe @geido @eschutho I was able to pinpoint the problem. The reason for the failure is because the screenshot generation on 4.1.0 RC3 caches the screenshots using the THUMBNAIL_CACHE_CONFIG which is a NullCache by default. A NullCache is a cache that does not cache anything, and that's why the frontend cannot find the screenshots and enters in a loop. The fix for this would be to make the default configuration of THUMBNAIL_CACHE_CONFIG similar to what we do with the Explore form data and save the thumbnails in the database using the SupersetMetastoreCache:

    THUMBNAIL_CACHE_CONFIG = {
        "CACHE_TYPE": "SupersetMetastoreCache",
        "CACHE_DEFAULT_TIMEOUT": // set a value
        # Should the timeout be reset when retrieving a cached value?
        "REFRESH_TIMEOUT_ON_RETRIEVAL": True,
        # The following parameter only applies to `MetastoreCache`:
        # How should entries be serialized/deserialized?
        "CODEC": // define the appropriate codec
    }
    

    Talking to @villebro about this issue, he raised a good point where previously Celery workers were not a hard requirement to install Superset but more of an optional feature. If the screenshot generation always requires Celery workers from now on, that could constitute a breaking change. Let me know your thoughts.

    Thanks @michael-s-molina we are currently discussing what the next steps should be for having Celery optional and the cache.
15. geido

    closed this as completedin #30755on Nov 1, 2024
16. github-project-automation

    moved this from Release Blockers to Done in Apache Superset 4.1on Nov 1, 2024
17. sadpandajoe

    moved this from Done to Cherried in Apache Superset 4.1on Nov 1, 2024