thread safety of MPI send using threads created with std::async

Question

According to this website, the usage of MPI::COMM_WORLD.Send(...) is thread safe. However in my application I often (not always) run into deadlocks or get segme

Answer 1

There are four levels of MPI thread safety, not all of them supported by every implementation: MPI_THREAD_SINGLE, MPI_THREAD_FUNNELED, MPI_THREAD_SERIALIZED and MPI_THREAD_MULTIPLE. The last one, which allows for a process to have multiple threads which may simultaneously call MPI functions, is probably the one you are interested in. So, first of all, you need to make sure your implementation supports MPI_THREAD_SERIALIZED.

The required level of thread safety must be specified by a call to MPI_Init_thread. After you have called MPI_Init_thread you should be able to safely call MPI functions in boost (POSIX) threads created on your own.