Hi. As per hash_range docs (http://www.boost.org/doc/libs/1_59_0/doc/html/hash/reference.html#boost.hash...): "This hash function is not intended for general use, and isn't guaranteed to be equal during separate runs of a program - so please don't use it for any persistent storage or communication." As per code (http://www.boost.org/doc/libs/1_59_0/boost/functional/hash/hash.hpp) it uses hash_combine_impl which doesn't use any random, process_id etc values which might change during new process launches. At the same time, in an example describing container usage in the shared memory (http://www.boost.org/doc/libs/1_59_0/doc/html/interprocess/allocators_contai...), boost::hash is being used: typedef boost::unordered_map < KeyType , MappedType , boost::hash<KeyType> ,std::equal_to<KeyType> , ShmemAllocator> MyHashMap; My question is: is it safe to use boost::hash in a shared (persistent) storage or it's safe only for a particular (non-pointer) types? In this case, boost::hash docs should be changed to mention this exceptions, because otherwise no one could use boost::hash in a shared memory containers.