Homework: Singularity

Submit two items to the the submission web site:

Answer the following question: In Singularity only one process can have a pointer to an object in the exchange heap. Ben proposes to modify Singularity to maintain a reference count for each object in the exchange heap and collect the object when the reference count is zero. When a process dies, he arranges to decrease the reference counter for each object in the exchange heap to which the dying process has a pointer. In Ben's design several processes can share an object in the heap. This would allow Ben to use the exchange heap, for example, for a shared buffer cache. What problem does Singularity try to solve by disallowing shared objects in the exchange heap?