[ZOOKEEPER-3063] Track outstanding changes with ArrayDeque

• Type: Improvement
• Status: Closed
• Priority: Trivial
• Resolution: Fixed
• Fix Version/s: 3.6.0, 3.5.5
• Component/s: server
• Labels: pull-request-available
• Assignee: Yisong Yue
• Reporter: Yisong Yue
• Created: 13/Jun/18 20:44
• Updated: 20/May/19 17:50
• Resolved: 15/Jun/18 05:41

Description

Outstanding changes are tracked with an ArrayList, which has O(N) remove from head (and possibly add) performance. This means that as we get further behind, we will slow down the processing of outstanding changes, which would make us get further behind.
We should switch to using ArrayDeque which achieves O(1) add and remove on both ends, which should result in much happiness.

Issue Links

• links to: GitHub Pull Request #543