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https://issues.apache.org/jira/browse/TINKERPOP-1925?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Stephen Mallette reassigned TINKERPOP-1925:
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    Assignee: Stephen Mallette  (was: Ted Wilmes)

> Don't apply PathRetractionStrategy recursively
> ----------------------------------------------
>
>                 Key: TINKERPOP-1925
>                 URL: https://issues.apache.org/jira/browse/TINKERPOP-1925
>             Project: TinkerPop
>          Issue Type: Improvement
>          Components: process
>    Affects Versions: 3.2.7
>            Reporter: Daniel Kuppitz
>            Assignee: Stephen Mallette
>            Priority: Major
>
> {{PathRetractionStrategy}} should not be applied recursively, if possible. 
> This is considered an anti-pattern and just recently it caused a lot of 
> trouble. This commit fixed the recent issue:
> https://github.com/apache/tinkerpop/commit/b8eb8a02f1675a1b22b86ccc54d22453c65f406f
> {{PathRetractionStrategy}} collects requirements of child traversals, before 
> other strategies have a chance to mutate them. When other strategies get to 
> the child traversals, mutate them and thus add or remove requirements, a few 
> things can go crazy, especially because traverser requirements get cached 
> when they're first requested.
> Since I do not fully understand the {{PathRetractionStrategy}} code, my fix 
> was actually a workaround. As you can see in the commit linked above, I 
> implemented the same anti-pattern in {{SubgraphStrategy}} and 
> {{IncidentToAdjacentStrategy}}; these are the 2 strategies that can 
> potentially change the traverser requirements.
> It would be nice to revert these changes and instead make 
> {{PathRetractionStrategy}} work like all others. However, I'm not sure if 
> that's even possible.



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