Database systems are usually built as a collection of processes (or threads) that communicate with one another via shared memory resources. The access to the shared memory region is restricted in what...

Database systems are usually built as a collection of processes (or threads) that communicate with one another via shared memory resources.
The access to the shared memory region is restricted in what way, if at all.
In order to serialise access to data structures in shared memory, is two-phase locking the most suitable method of doing so? Give an explanation for your response.