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Don't share state in build task #3946

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merged 2 commits into from Apr 19, 2018
Merged

Don't share state in build task #3946

merged 2 commits into from Apr 19, 2018

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@agjohnson
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@agjohnson agjohnson commented Apr 13, 2018

Move task steps to an isolated class, instead of possibly sharing state in
between tasks. This bug is not consistently reproduceable, but one consistent
way to reproduce is to drop to rdb on the UpdateDocsTask run method.
Previously, if you did this while running 2 celery processes, and triggered 2
builds, you could witness state changing on the task instance. By moving state
to a separate class that is instantiated on each task execution, this completely
avoids shared state in these tasks.

Move task steps to an isolated class, instead of possibly sharing state in
between tasks. This bug is not consistently reproduceable, but one consistent
way to reproduce is to drop to ``rdb`` on the UpdateDocsTask run method.
Previously, if you did this while running 2 celery processes, and triggered 2
builds, you could witness state changing on the task instance. By moving state
to a separate class that is instantiated on each task execution, this completely
avoids shared state in these tasks.
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@ericholscher ericholscher left a comment

This was a good deal less intrusive than I was thinking in the abstract. I believe this will introduce a number of downstream bugs where we were accessing state that was stale, but throwing exceptions instead of using bad data is good. 👍

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@ericholscher ericholscher commented Apr 14, 2018

I do think we should have docstrings here explaining the design though. Otherwise I could see this getting refactored away as unneeded complexity.

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@humitos humitos left a comment

I like the approach used here, 👍

I'd like to echo what Eric said regarding writing a good docstring since it wasn't clear to find the issue and also we don't have a good way to write a test for this.

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@humitos humitos commented Apr 14, 2018

I want to add some context here that I found while reading how to use the celery framework instead a custom workaround to fix this:

Those two links, talks about similar issues.

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@humitos humitos left a comment

👍

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@agjohnson agjohnson commented Apr 19, 2018

Opened #3973 and #3974 to address some of the issues not addressed here.

@agjohnson agjohnson merged commit df25dbc into master Apr 19, 2018
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@agjohnson agjohnson deleted the agj/isolate-build-task branch Apr 19, 2018
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3 participants