Managing lifecycles of sets of foreign resources

Techniques for managing lifecycles of sets of foreign resources are disclosed, including: opening, in a runtime environment configured to use a garbage collector to manage memory in a heap, a memory session; allocating a first subset of a set of foreign memory to a memory segment associated with the memory session, the foreign memory including off-heap memory that is not managed by the garbage collector; encountering, in the runtime environment, an instruction to close the memory session; responsive to encountering the instruction to close the memory session, deallocating the subset of the set of foreign memory.