[LANG-334] Enum is not thread-safe

• Type: Bug
• Status: Closed
• Priority: Major
• Resolution: Fixed
• Fix Version/s: 2.4
• Assignee: Unassigned
• Reporter: Michael Sclafani
• Created: 14/May/07 22:30
• Updated: 05/Sep/07 10:14
• Resolved: 05/Sep/07 10:14

Description

Enum uses no synchronization. Even if you assume that instances are only declared statically, the cEnumClasses map is global and can be written to when a thread triggers static initialization of B.class while some other thread is doing getEnumList(A.class). Unsynchronized access of a map undergoing mutation is not thread-safe.

This isn't theoretical. We're seeing ValuedEnum.getEnum(X.class, 0) return null after returning the correct value over 100,000 times, and then return the correct value again on the next invocation.