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https://issues.apache.org/jira/browse/WICKET-6800?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Martin Tzvetanov Grigorov updated WICKET-6800:
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Affects Version/s: (was: 9.0.0-M6)
9.0.0-M5
> Use LinkedHashSet instead of LinkedList for AjaxRequestHandler#listeners
> ------------------------------------------------------------------------
>
> Key: WICKET-6800
> URL: https://issues.apache.org/jira/browse/WICKET-6800
> Project: Wicket
> Issue Type: Improvement
> Components: wicket
> Affects Versions: 9.0.0-M5, 8.8.0
> Reporter: Martin Tzvetanov Grigorov
> Assignee: Martin Tzvetanov Grigorov
> Priority: Minor
> Fix For: 7.17.0, 9.0.0-M6, 8.9.0
>
>
> https://github.com/apache/wicket/pull/438
> Urs Joss:
> While migrating my project (see PR there) from the mocking library mockito to
> mock, I ran into weird performance issues. The build time jumped from roughly
> 20 minutes to eventually more than 4 hours. I took some effort improving
> various things in my own code (less mocking, more memory etc.) but did not
> bring it down considerably until I addressed a bottleneck I found in wicket.
> AjaxRequestHandler maintains a collection of listeners in a LinkedList. When
> client code adds a new listener calling method addListener, it uses the
> collection's method contains to assert we don't add a listener to the
> collection twice. This doesn't scale well. For some reason, my setup with
> mockk seems to add many more listeners than what my code did with mockito, so
> I ran into this issue with continuously slower test executions.
> I managed to temporarily resolve the problem in my project by plugging in my
> own copy of AjaxRequestHandler where I swapped the collection type from
> LinkedList to LinkedHashSet (calling setAjaxRequestTargetProvider in my
> TestApplication). With this approach the total build time went down again to
> 20-30 minutes.
> This PR serves the purpose of starting a discussion about whether this change
> would be feasible to implement in wicket directly. To me, it is not apparent
> why a LinkedList had been chosen initially. The LinkedHashSet performs much
> better with contains and still preserves insertion order. If that latter
> should turn out to be not relevant, we could even consider using a HashSet
> instead of a linked HashSet, but I presume insertion order is important.
> A separate topic on my side will be to figure out why my setup with mockito
> seemed to work well while migrating to mockk surfaced this issue.
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