This is for YADE, our software for discrete modelling.
Imagine a std::vector of 125000 spheres:
https://yade-dem.org/wiki/Screenshots_and_videos#Ball_Mill_-_125_000_sphere s
it is currently parallelized with OPEN MP, but there are some global locks in few places. Saying that each sphere is atomic (instead of locking whole container) would solve the problem.
Actually you will only add problems if you do that. You need to use a concurrent container, not a classical containers with atomics variables. First, atomic is more expensive than you think, to convince yourself of this, benchmark the two following codes: int i = 0; while(i < 10 * 1000 * 1000) ++i; and atomic<int> i = 0; while(i < 10 * 1000 * 1000) ++i; Second, you will lock nevertheless because your memory entries will belong to the same cache line. You need to use a special allocator that makes sure that each entry doesn't overlap so that reading and writing to a slot will not result in false sharing. Third, wrapping a variable in atomic doesn't magically make your variable immune to the reader/writer problem (or other synchronization problems). You probably want access to your object to be atomic, in which case a container that guarantees that affectation to an entry is atomic is enough for you. Making your business logic reader/writer proof is generally more complex than a simple atomic<> wrapping. All in all, I think that what you need is a concurrent_vector<T> not a vector<atomic<T>>. Regards. -Edouard __________ Information from ESET NOD32 Antivirus, version of virus signature database 5075 (20100430) __________ The message was checked by ESET NOD32 Antivirus. http://www.eset.com