"Internal, non-movable pImpl-lite implementation of Server_session_mv class template.">Server_session_impl</a></code>. There <em>is</em> a problem. Interestingly this time it really does <em>not</em> matter whether A is server or client-side. In SHM-jemalloc the session-scope arenas are not 1 but 2: A has an arena, from which process A can allocate, and in which process A shall deallocate. B has an arena, from which process B can allocate, and in which process B shall deallocate. If B borrows object X from 