The ThreadHint parameter can be used to request, but not guarantee, that a task executes on a particular thread. The value passed should be the integer index in range [0..ThreadCount) of the thread in that executor. You can retrieve the current thread index using tmc::current_thread_index().

tmc::post()

template<typename E, typename TaskOrFunc>
void tmc::post(E &Executor, TaskOrFunc &&Work, size_t Priority = 0, size_t ThreadHint = NO_HINT) noexcept

Submits Work for execution on Executor at priority Priority. Tasks or functors that return values cannot be submitted this way; see post_waitable instead.

inline size_t tmc::current_thread_index() noexcept

Returns the current thread’s index within its executor. Each executor’s threads are numbered independently, starting from 0. Returns -1 if this thread is not associated with an executor.