Possible subtle memory model error in ClassValue

Doug Lea dl at cs.oswego.edu
Mon Aug 10 12:17:44 UTC 2020

Catching up...

As implied in other posts, the minimal fix is to add a trailing release 
fence (using Unsafe?) to the constructor. Or less delicately, to access 
only using acquire/release (which will cost a bit on ARM/Power, but 
probably not noticeable on x86), or most simply (but expensively) to 
declare the field volatile.

Also, as Hans noted, the consensus seems to be that there not enough to 
be gained by always adding a release fence to constructors. A few errors 
like this might never occur, but other related anomalies with non-final 
field accesses would remain.


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