It's one of the primary goals of the project > Provide low-level buildings blocks for pthreads-style shared memory: shared memory between threads, atomics and

It's one of the primary goals of the project > Provide low-level buildings blocks for pthreads-style shared memory: shared memory between threads, atomics and futexes (or synchronic). New atomic memory operators, including loads/stores annotated with their atomic ordering property, will follow the C++11 memory model, similarly to the PNaCl atomic support and the SharedArrayBuffer proposal. Regular loads and stores will be bound by a happens-before relationship to atomic operators in the same thread of execution, which themselves synchronize-with atomics in other threads. Following these rules, regular load/store operators can still be elided, duplicated, and split up. This guarantees that data-race free code executes as if it were sequentially consistent. Even when there are data races, WebAssembly will ensure that the nondeterminism remains limited and local.