#50 Unexpected race conditions

[Nigel Phillips]

Looks like all accesses to shared data might have to be
synchronized.
See "Double-checked locking: Clever, but broken" for an
example.
http://www.javaworld.com/javaworld/jw-02-2001/jw-0209-double.html

Also: http://www.cs.umd.edu/~pugh/java/memoryModel/

Given the likely performance hit, this is not a
priority.