[WICKET-6833] Reduce allocations when merging page parameters

• Type: Improvement
• Status: Resolved
• Priority: Major
• Resolution: Fixed
• Affects Version/s: 9.0.0
• Fix Version/s: 9.1.0, 8.10.0
• Component/s: wicket-core
• Assignee: Thomas Heigl
• Reporter: Thomas Heigl
• Created: 25/Sep/20 13:48
• Updated: 28/Sep/20 11:06
• Resolved: 28/Sep/20 09:22

Description

My profiler shows a significant amount of allocations and list resizing coming from PageParameters.mergeWith.

The method unnecessarily creates ArrayLists, TreeSets, unmodifiable wrappers, and does not size the underlying list of NamedPair correctly when merging page parameters with multiple values.

It can be called hundreds of times per request for applications with a high number of mounted pages and resources.