ghalliday/HPCC-Platform — comment on commit 45b9e19c71ccc06d5b5c905125f79a9a0457347e
File: system/jlib/jmutex.hpp line 346
By ghalliday:

It looks like it already is volatile.
I think we still need the barrier - it is there to prevent code that precedes the set of value to 0 from being moved after it.