[KAFKA-13791] Fix FetchResponse#`fetchData` and `forgottenTopics`: Assignment of lazy-initialized members should be the last step with double-checked locking

• Type: Bug
• Status: Resolved
• Priority: Trivial
• Resolution: Fixed
• Affects Version/s: 3.0.1
• Fix Version/s: 3.3.0
• Component/s: clients
• Assignee: Unassigned
• Reporter: YunKui Lu
• Created: 01/Apr/22 02:29
• Updated: 05/Apr/22 07:28
• Resolved: 05/Apr/22 07:28

Description

Double-checked locking can be used for lazy initialization of volatile fields, but only if field assignment is the last step in the synchronized block. Otherwise, you run the risk of threads accessing a half-initialized object.

The problem is consistent with KAFKA-13777

Issue Links

• links to: GitHub Pull Request #11981